52 results on '"Jean-Michel Panoff"'
Search Results
2. Sex-dependent impact of Roundup on the rat gut microbiome
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Veronica L. Lozano, Nicolas Defarge, Louis-Marie Rocque, Robin Mesnage, Didier Hennequin, Renaud Cassier, Joël Spiroux de Vendômois, Jean-Michel Panoff, Gilles-Eric Séralini, and Caroline Amiel
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Toxicology. Poisons ,RA1190-1270 - Abstract
A growing body of research suggests that dysbiosis of the gut microbiota induced by environmental pollutants, such as pesticides, could have a role in the development of metabolic disorders. We have examined the long-term effects of 3 doses of the Roundup(R) herbicide (made of glyphosate and formulants) on the gut microbiota in male and female Sprague-Dawley rats. A total of 141 bacteria families were identified by a 16S sequencing analysis approach. An OPLS-DA analysis revealed an increased Bacteroidetes family S24-7 and a decreased Lactobacillaceae in 8 out of the 9 females treated with 3 different doses of R (n = 3, for each dose). These effects were confirmed by repetitive sequence-based PCR fingerprinting showing a clustering of treated females. A culture-based method showed that R had a direct effect on rat gut microbiota. Cultivable species showed different sensitivities to R, including the presence of a high tolerant or resistant strain identified as Escherichia coli by 16S rRNA sequencing. The high tolerance of this E. Coli strain was explained by the absence of the EPSPS gene (coding glyphosate target enzyme) as shown by DNA amplification. Overall, these gut microbiome disturbances showed a substantial overlap with those associated with liver dysfunction in other studies. In conclusion, we revealed that an environmental concentration of R (0.1 ppb) and other two concentrations (400 ppm and 5,000 ppm) have a sex-dependent impact on rat gut microbiome composition and thus warrants further investigation. Keywords: Glyphosate, Roundup, Gut microbiome, Pesticides, Toxicity
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- 2018
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3. Impact of Antibiotics on Efficacy of Cry Toxins Produced in Two Different Genetically Modified Bt Maize Varieties in Two Lepidopteran Herbivore Species, Ostrinia nubilalis and Spodoptera littoralis
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Angelika Hilbeck, Nicolas Defarge, Thomas Bøhn, Michelle Krautter, Constanze Conradin, Caroline Amiel, Jean-Michel Panoff, and Miluse Trtikova
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ecotoxicology ,Bacillus thuringiensis ,Cry toxins ,antibiotics ,nontarget organisms ,lepidoptera ,Medicine - Abstract
The insecticidal crystal proteins from Bacillus thuringiensis (Bt) are widely-used biopesticides that are used both as Bt spore-crystal preparations in sprayable formulations and as activated toxins in genetically modified (GM) plants. Models for their modes of action have been proposed but many issues remain unresolved. Among those is the role of commensal gut bacteria in target insect death: previous studies showed that antibiotics attenuate the toxicity of Bt sprays. We tested whether antibiotics interfere with the effects of GM plant-produced Bt toxins in larvae of two Lepidopteran species, the European corn borer Ostrinia nubilalis and the cotton leafworm Spodoptera littoralis. The larvae were reared on artificial diet with or without antibiotics and, thereafter, fed two varieties of Bt GM maize in comparison to conventional non-Bt maize leaves sprayed with antibiotic solution and/or with a Bt formulation. Antibiotics significantly reduced or delayed the toxicity of Cry toxins, although to a lesser extent than previously reported for Bt-sprays. This supports the hypothesis that Cry toxins induce mortality by themselves in the absence of Bt bacteria and spores, and of commensal gut bacteria. However, larvae that were not treated with antibiotics died faster and at a higher rate which was further compounded by plant variety and species sensitivity. These findings support a hypothesis that toxicemia alone can inflict significant mortality. However, in the absence of antibiotics, the gut bacteria likely enhance the Cry toxin effect by inflicting, additionally, bacterial septicemia. This has important implications in field situations where antibiotic substances are present—e.g., from manure of animals from conventional production systems—and for ecotoxicological testing schemes of Bt toxins and nontarget organisms that are often using artificial diets enriched with high concentrations of antibiotics.
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- 2018
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4. Cropping Practices and Fungal Contamination in Banana Plantations in Côte d’Ivoire
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David Garon, Tia Jean Gonnety, Toualy Serge Ouin, Marina Kouss eacu, Jean-Michel Panoff, Stéphanie Gente, and Jean-Philippe Rioult
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Infectious Diseases ,Geography ,Agroforestry ,Fungal contamination ,Cote d ivoire ,Applied Microbiology and Biotechnology ,Microbiology ,Cropping ,Food Science - Published
- 2020
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5. Multi-omics phenotyping of the gut-liver axis reveals metabolic perturbations from a low-dose pesticide mixture in rats
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Mariam Ibragim, Romy D. Zwittink, Quinten R Ducarmon, Michael Antoniou, Laura Falcioni, Maxime Teixeira, Caroline Amiel, Jean-Michel Panoff, Robin Mesnage, Daniele Mandrioli, Emma Bourne, Fiorella Belpoggi, Charles A. Mein, and Emanuel Savage
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0301 basic medicine ,QH301-705.5 ,Medicine (miscellaneous) ,010501 environmental sciences ,Biology ,Pharmacology ,medicine.disease_cause ,01 natural sciences ,General Biochemistry, Genetics and Molecular Biology ,Article ,Transcriptome ,Rats, Sprague-Dawley ,03 medical and health sciences ,chemistry.chemical_compound ,Metabolomics ,medicine ,Animals ,Biology (General) ,Pesticides ,0105 earth and related environmental sciences ,Nicotinamide ,Dose-Response Relationship, Drug ,Pesticide ,Rats ,Gastrointestinal Tract ,030104 developmental biology ,Phenotype ,chemistry ,Risk factors ,Liver ,Chlorpyrifos ,Toxicity ,Female ,General Agricultural and Biological Sciences ,Oxidative stress ,Hormone - Abstract
Health effects of pesticides are not always accurately detected using the current battery of regulatory toxicity tests. We compared standard histopathology and serum biochemistry measures and multi-omics analyses in a subchronic toxicity test of a mixture of six pesticides frequently detected in foodstuffs (azoxystrobin, boscalid, chlorpyrifos, glyphosate, imidacloprid and thiabendazole) in Sprague-Dawley rats. Analysis of water and feed consumption, body weight, histopathology and serum biochemistry showed little effect. Contrastingly, serum and caecum metabolomics revealed that nicotinamide and tryptophan metabolism were affected, which suggested activation of an oxidative stress response. This was not reflected by gut microbial community composition changes evaluated by shotgun metagenomics. Transcriptomics of the liver showed that 257 genes had their expression changed. Gene functions affected included the regulation of response to steroid hormones and the activation of stress response pathways. Genome-wide DNA methylation analysis of the same liver samples showed that 4,255 CpG sites were differentially methylated. Overall, we demonstrated that in-depth molecular profiling in laboratory animals exposed to low concentrations of pesticides allows the detection of metabolic perturbations that would remain undetected by standard regulatory biochemical measures and which could thus improve the predictability of health risks from exposure to chemical pollutants., Using a multi-omics platform, Mesnage et al present an extensive dataset that reports the effects of low-dose pesticides frequently detected in food on Sprague-Dawley rats. This study suggests potential metabolic biomarkers that may predict health risks from exposure to chemical pollutants.
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- 2021
6. Use of Shotgun Metagenomics and Metabolomics to Evaluate the Impact of Glyphosate or Roundup MON 52276 on the Gut Microbiota and Serum Metabolome of Sprague-Dawley Rats
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Quinten R Ducarmon, Daniele Mandrioli, Romy D. Zwittink, Jean Michel Panoff, Laura Falcioni, Maxime Teixeira, Anna Caldwell, Robin Mesnage, Francesca Mazzacuva, Fiorella Belpoggi, Caroline Amiel, John M. Halket, and Michael Antoniou
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animal structures ,Health, Toxicology and Mutagenesis ,Glycine ,010501 environmental sciences ,Gut flora ,01 natural sciences ,Microbiology ,Rats, Sprague-Dawley ,03 medical and health sciences ,chemistry.chemical_compound ,0302 clinical medicine ,Metabolomics ,Sprague dawley rats ,Metabolome ,Animals ,Shikimate pathway ,030212 general & internal medicine ,Health implications ,0105 earth and related environmental sciences ,Acinetobacter ,integumentary system ,biology ,Herbicides ,Research ,fungi ,Public Health, Environmental and Occupational Health ,food and beverages ,biology.organism_classification ,Gastrointestinal Microbiome ,Rats ,Blood ,chemistry ,Glyphosate ,Metagenomics ,Shotgun metagenomics - Abstract
BACKGROUND: There is intense debate on whether glyphosate can inhibit the shikimate pathway of gastrointestinal microorganisms, with potential health implications.OBJECTIVES: We tested whether glyphosate or its representative EU herbicide formulation Roundup MON 52276 affects the rat gut microbiome.METHODS: We combined cecal microbiome shotgun metagenomics with serum and cecum metabolomics to assess the effects of glyphosate [0.5, 50, 175 mg=kg body weight oBW thorn per day] or MON 52276 at the same glyphosate-equivalent doses, in a 90-d toxicity test in rats.RESULTS: Glyphosate and MON 52276 treatment resulted in ceca accumulation of shikimic acid and 3-dehydroshikimic acid, suggesting inhibition of 5-enolpyruvylshikimate-3-phosphate synthase of the shikimate pathway in the gut microbiome. Cysteinylglycine, c-glutamylglutamine, and valylglycine levels were elevated in the cecal microbiome following glyphosate and MON 52276 treatments. Altered cecum metabolites were not differentially expressed in serum, suggesting that the glyphosate and MON 52276 impact on gut microbial metabolism had limited consequences on physiological biochemistry. Serum metabolites differentially expressed with glyphosate treatment were associated with nicotinamide, branched-chain amino acid, methionine, cysteine, and taurine metabolism, indicative of a response to oxidative stress. MON 52276 had similar, but more pronounced, effects than glyphosate on the serum metabolome. Shotgun metagenomics of the cecum showed that treatment with glyphosate and MON 52276 resulted in higher levels of Eggerthella spp., Shinella zoogleoides, Acinetobacter johnsonii, and Akkermansia muciniphila. Shinella zoogleoides was higher only with MON 52276 exposure. In vitro culture assays with Lacticaseibacillus rhamnosus strains showed that Roundup GT plus inhibited growth at concentrations at which MON 52276 and glyphosate had no effect.DISCUSSION: Our study highlights the power of multi-omics approaches to investigate the toxic effects of pesticides. Multi-omics revealed that glyphosate and MON 52276 inhibited the shikimate pathway in the rat gut microbiome. Our findings could be used to develop biomarkers for epidemiologi cal studies aimed at evaluating the effects of glyphosate herbicides on humans. https://doi.org/10.1289/EHP6990
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- 2021
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7. Multi-omics phenotyping of the gut-liver axis allows health risk predictability from in vivo subchronic toxicity tests of a low-dose pesticide mixture
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Emanuel Savage, Charles A. Mein, Fiorella Belpoggi, Quinten R Ducarmon, Caroline Amiel, Michael Antoniou, Emma Bourne, Jean-Michel Panoff, Daniele Mandrioli, Romy D. Zwittink, Maxime Teixeira, Laura Falcioni, and Robin Mesnage
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Transcriptome ,chemistry.chemical_compound ,Acceptable daily intake ,chemistry ,Nicotinamide ,Lactobacillus rhamnosus ,biology ,Pesticide residue ,In vivo ,Chlorpyrifos ,Pesticide ,Pharmacology ,biology.organism_classification - Abstract
Human health effects from chronic exposure to mixtures of pesticide residues are little investigated. We compared standard histopathology and serum biochemistry measures and multi-omics analyses in an in vivo subchronic toxicity test of a mixture of six pesticide active ingredients frequently detected in foodstuffs (azoxystrobin, boscalid, chlorpyrifos, glyphosate, imidacloprid and thiabendazole). Sprague-Dawley rats were administered with the pesticide mixture with each ingredient at its regulatory permitted acceptable daily intake. Analysis of water and feed consumption, body weight, histopathology and serum biochemistry showed little or no physiological effects from exposure to the pesticide mixture. In marked contrast, analysis of the host-gut microbiome axis using serum and caecum metabolomics revealed that nicotinamide and tryptophan metabolism were affected, which suggested the initiation of a cell danger response, including adaptation to oxidative stress. Only limited effects were detected on the caecum microbiota by shotgun metagenomics. Further analyses of in vitro bacterial cultures showed that growth of Lactobacillus rhamnosus and Escherichia coli strains was negatively impacted by the pesticide mixture at concentrations that were not inhibitory when exposure was to a single agent. Transcriptomics of the liver showed that 257 genes had their expression changed. Gene functions affected included those involved in the regulation of response to hormones and correlated with previously reported transcriptome changes following administration of nicotinamide. Genome-wide DNA methylation analysis of the same liver samples showed that 4255 CpG sites were differentially methylated (> 10% difference). Overall, we demonstrated that unlike standard blood biochemical and organ histological analysis, in-depth molecular profiling using a combination of high-throughput ‘-omics’ methods in laboratory animals exposed to low concentrations of pesticides reveals metabolic effects on the gut-liver axis, which can potentially be used as biomarkers for the prediction of future negative health outcomes. Our data suggest that adoption of multi-omics as part of regulatory risk assessment procedures will result in more accurate outcome measures, with positive public health implications.
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- 2020
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8. Shotgun metagenomics and metabolomics reveal glyphosate alters the gut microbiome of Sprague-Dawley rats by inhibiting the shikimate pathway
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Jean-Michel Panoff, Michael Antoniou, Caroline Amiel, Romy D. Zwittink, Maxime Teixeira, Robin Mesnage, Daniele Mandrioli, Fiorella Belpoggi, Quinten R Ducarmon, and Laura Falcioni
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Caecum ,chemistry.chemical_compound ,Gastrointestinal tract ,Metabolomics ,chemistry ,Glyphosate ,Aromatic amino acids ,Shikimate pathway ,Microbiome ,Biology ,Shikimic acid ,biology.organism_classification ,Microbiology - Abstract
There is intense debate as to whether glyphosate can interfere with aromatic amino acid biosynthesis in microorganisms inhabiting the gastrointestinal tract, which could potentially lead to negative health outcomes. We have addressed this major gap in glyphosate toxicology by using a multi-omics strategy combining shotgun metagenomics and metabolomics. We tested whether glyphosate (0.5, 50, 175 mg/kg bw/day), or its representative EU commercial herbicide formulation MON 52276 at the same glyphosate equivalent doses, has an effect on the rat gut microbiome in a 90-day subchronic toxicity test. Clinical biochemistry measurements in blood and histopathological evaluations showed that MON 52276 but not glyphosate was associated with statistically significant increase in hepatic steatosis and necrosis. Similar lesions were also present in the liver of glyphosate-treated groups but not in the control group. Caecum metabolomics revealed that glyphosate inhibits the enzyme 5-enolpyruvylshikimate-3-phosphate (EPSP) synthase in the shikimate pathway as evidenced by an accumulation of shikimic acid and 3-dehydroshikimic acid. Levels of caecal microbiome dipeptides involved in the regulation of redox balance (γ-glutamylglutamine, cysteinylglycine, valylglycine) had their levels significantly increased. Shotgun metagenomics showed that glyphosate affected caecum microbial community structure and increased levels of Eggerthella spp. and Homeothermacea spp.. MON 52276, but not glyphosate, increased the relative abundance of Shinella zoogleoides. Since Shinella spp. are known to degrade alkaloids, its increased abundance may explain the decrease in solanidine levels measured with MON 52776 but not glyphosate. Other glyphosate formulations may have different effects since Roundup® GT Plus inhibited bacterial growth in vitro at concentrations at which MON 52276 did not present any visible effect. Our study highlights the power of a multiomics approach to investigate effects of pesticides on the gut microbiome. This revealed the first biomarker of glyphosate effects on rat gut microbiome. Although more studies will be needed to ascertain if there are health implications arising from glyphosate inhibition of the shikimate pathway in the gut microbiome, our findings can be used in environmental epidemiological studies to understand if glyphosate can have biological effects in human populations.Graphical Abstract
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- 2019
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9. Binary approaches to biological risks
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Jean Michel Panoff, Ange-Hélène Yebga Hot, Marina Koussemon, Marie-Pierre Baudin-Maurin, and Toualy Serge Thibaut Ouina
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Risk analysis (engineering) ,Collateral ,media_common.quotation_subject ,Damages ,media_common.cataloged_instance ,Management Science and Operations Research ,Statistics, Probability and Uncertainty ,Business and International Management ,European union ,Hazard ,Indigenous ,media_common ,Diversity (politics) - Abstract
Concerning biological risks, European Union and Governments policies mainly rely on two scientific classifications (2000/54/EC; 2009/41/EC). However, recent health concerns (e.g., avian flu epidemic) and environmental damages (e.g., GMOs) have questioned the limitations of those categorisations, stressing the need for accurate tools to assess and manage biological risks. The aim of this study is to provide an original analysis of the biological risks, beyond the common categorisations, taking into account, by using binary approaches, the biological risks diversity. This research work has non-exhaustively identified ten couples, namely microbiology/macrobiology, natural/provoked risks, naturally pathogen biological agents/genetically modified organisms, indigenous/invasive states, health/environment, primary target/collateral consequences, synthetic/natural biology, exobiology/endobiology, proven/potential risks and assessment/management. This present study will likely be useful to improve the decision-making process regarding the biological risks.
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- 2020
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10. A Mesocosm ofLactobacillus johnsonii,Bifidobacterium longum, andEscherichia coliin the Mouse Gut
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Jean-Michel Panoff, Enea Rezzonico, Harald Brüssow, Fabrizio Arigoni, and Emmanuel Denou
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Bifidobacterium longum ,Lactobacillus paracasei ,biology ,food and beverages ,Cell Biology ,General Medicine ,Gut flora ,biology.organism_classification ,medicine.disease_cause ,Small intestine ,Microbiology ,Cecum ,fluids and secretions ,medicine.anatomical_structure ,Genetics ,medicine ,Molecular Biology ,Escherichia coli ,Bacteria ,Lactobacillus johnsonii - Abstract
The relative contribution of competition and cooperation at the microbe-microbe level is not well understood for the bacteria constituting the gut microbiota. The high number and variability of human gut commensals have hampered the analysis. To get some insight into the question how so many different bacterial species can coexist in the mammalian gut, we studied the interaction between three human gut commensals (Escherichia coli K-12, Lactobacillus johnsonii NCC533, and Bifidobacterium longum NCC2705) in the intestine of gnotobiotic mice. The bacterial titers and their anatomical distribution were studied in the colonized mice. L. johnsonii achieved the highest cell counts in the stomach, while B. longum dominated the colon. The colon was also the intestinal location in which B. longum displayed the highest number of expressed genes, followed by the cecum and the small intestine. Addition of further bacterial strains led to strikingly different results. A Lactobacillus paracasei strain coexisted, while a second B. longum strain was excluded from the system. Notably, this strain lacked an operon involved in the degradation, import, and metabolism of mannosylated glycans. Subsequent introduction of the E. coli Nissle strain resulted in the elimination of L. johnsonii NCC533 and E. coli K-12, while B. longum NCC2705 showed a transient decrease in population size, demonstrating the dynamic nature of microbe-microbe interactions. The study of such simple interacting bacterial systems might help to derive some basic rules governing microbial ecology within the mammalian gut.
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- 2009
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11. The Role of Prophage for Genome Diversification within a Clonal Lineage of Lactobacillus johnsonii : Characterization of the Defective Prophage LJ771
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Harald Brüssow, Jean-Michel Panoff, Bernard Berger, Anne-Cécile Pittet, Raymond David Pridmore, Marie-Camille Zwahlen, Marco Ventura, Emmanuel Denou, and Caroline Barretto
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Genes, Viral ,Genotype ,Prophages ,Molecular Sequence Data ,Bacteriophages, Transposons, and Plasmids ,Lactobacillus gasseri ,Microbiology ,Defective virus ,Plasmid ,Lysogen ,Amino Acid Sequence ,Molecular Biology ,Prophage ,Lactobacillus johnsonii ,Genetics ,Base Sequence ,Models, Genetic ,biology ,Genetic Complementation Test ,Defective Viruses ,biology.organism_classification ,Temperateness ,Lactobacillus ,Phenotype ,Gene cassette ,Methionine Sulfoxide Reductases ,DNA, Viral ,Oxidoreductases ,Sequence Alignment ,Genome, Bacterial - Abstract
Two independent isolates of the gut commensal Lactobacillus johnsonii were sequenced. These isolates belonged to the same clonal lineage and differed mainly by a 40.8-kb prophage, LJ771, belonging to the Sfi11 phage lineage. LJ771 shares close DNA sequence identity with Lactobacillus gasseri prophages. LJ771 coexists as an integrated prophage and excised circular phage DNA, but phage DNA packaged into extracellular phage particles was not detected. Between the phage lysin gene and attR a likely mazE (“antitoxin”)/ pemK (“toxin”) gene cassette was detected in LJ771 but not in the L. gasseri prophages. Expressed pemK could be cloned in Escherichia coli only together with the mazE gene. LJ771 was shown to be highly stable and could be cured only by coexpression of mazE from a plasmid. The prophage was integrated into the methionine sulfoxide reductase gene ( msrA ) and complemented the 5′ end of this gene, creating a protein with a slightly altered N-terminal sequence. The two L. johnsonii strains had identical in vitro growth and in vivo gut persistence phenotypes. Also, in an isogenic background, the presence of the prophage resulted in no growth disadvantage.
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- 2008
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12. Effect of pesticides and micro-organisms on earthworm Eisenia fetida (Savigny, 1826)
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Toualy, S. Ouina, primary, Jean-Michel, Panoff, additional, Marina, Koussémon, additional, and Tia, J. Gonnety, additional
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- 2017
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13. Cryotolerance of Lactobacillus delbrueckii subsp. bulgaricus CFL1 is modified by acquisition of antibiotic resistance
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Jean-Michel Panoff, Catherine Béal, Bouachanh Thammavongs, Jean-Paul Rivals, and Micheline Guéguen
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Hot Temperature ,Time Factors ,Mutant ,Bacitracin ,General Biochemistry, Genetics and Molecular Biology ,Microbiology ,Lactobacillus ,Drug Resistance, Bacterial ,Freezing ,medicine ,Selection, Genetic ,Novobiocin ,Cryopreservation ,Lactobacillus delbrueckii ,Microbial Viability ,biology ,Wild type ,Kanamycin ,General Medicine ,Hydrogen-Ion Concentration ,biology.organism_classification ,Streptomycin ,Mutation ,General Agricultural and Biological Sciences ,Lactobacillus delbrueckii subsp. bulgaricus ,medicine.drug - Abstract
This study aimed to relate the acquisition of different antibiotic resistances and the corresponding physiological responses to cold stress of Lactobacillus delbrueckii subsp. bulgaricus strain CFL1. Six resistant mutants were spontaneously obtained and studied depending on the target of the antibiotic: (i) bacitracin and vancomycin (Bac(R), Van(R), wall synthesis), (ii) novobiocin (Nov(R), DNA replication), and (iii) kanamycin, spiramycin, streptomycin (Kan(R), Spi(R), Str(R), RNA translation). The mutations modified the growth and the cold stress response at three different physiological levels: (i) Van(R) and Spi(R) mutants showed significant lower growth rates compared to the wild type strain. (ii) Van(R) and Bac(R) mutants displayed a slightly higher resistance to a freezing-thawing challenge whereas Str(R) and Spi(R) mutants were more sensitive compared to the wild type. (iii) The recovery of acidification activity after freezing and during frozen storage was improved by considering the Nov(R) strain, but not with the Van(R) and Spi(R) mutants. Thus, acquisition of some antibiotic resistance by spontaneous mutation led to modification of the cold stress response. The hypothesis of a unique cellular thermostat is discussed regarding the diversity of the tested antibiotics.
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- 2007
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14. Improvement of the cryopreservation of the fungal starter Geotrichum candidum by artificial nucleation and temperature downshift control
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Micheline Guéguen, Jean-Michel Panoff, Ghalia Missous, V. Dieuleveux, and Bouachanh Thammavongs
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Cryopreservation ,Time Factors ,biology ,Food industry ,business.industry ,Microorganism ,Nucleation ,Water ,Geotrichum ,Ripening ,General Medicine ,biology.organism_classification ,General Biochemistry, Genetics and Molecular Biology ,Starter ,Freezing ,Botany ,Food Microbiology ,Pseudomonas syringae ,Food science ,General Agricultural and Biological Sciences ,business ,Bacterial Outer Membrane Proteins - Abstract
Food industry tends towards the use of controlled microorganisms in order to improve its technologies including frozen starter production. The fungus Geotrichum candidum, which is currently found in various environments, is widely used as ripening agent in some specific cheese making process. In order to optimize the cryopreservation of this microorganism, freezing experiments were carried out using a Peltier cooler-heater incubator, which permits to control the temperature downshift from +20 to -10 degrees C in time period ranges from 20 to 40min depending on the experiments. Concomitantly, study of the effect of an industrial ice nucleator protein derived from Pseudomonas syringae (SNOMAX) on the dynamic of freezing of G. candidum was carried out. Our results showed that the addition of this protein in the microbiological suspension has different complementary effects: (i) the synchronization of the different samples nucleation, leading to an homogeneous and earlier freezing, (ii) the increase of the freezing point temperature from -8.6 to -2.6 degrees C, (iii) a significant decrease of the lethality of G. candidum cells subjected to a freezing-thawing cycles challenge.
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- 2007
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15. Interspecies Protection against Freezing Stress within a Food Microbial Community
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Jean-Michel Panoff, Micheline Guéguen, Emmanuel Denou, and Bouachanh Thammavongs
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biology ,Thermophile ,Microorganism ,Lactococcus lactis ,Biomedical Engineering ,food and beverages ,Geotrichum ,Cell Biology ,Microbial consortium ,biology.organism_classification ,General Biochemistry, Genetics and Molecular Biology ,Microbiology ,Microbial population biology ,Lactobacillus ,Biotechnology ,Mesophile - Abstract
This study was completed on an artificial microbial community (consortium) including three microorganisms of dairy interest, two mesophilic (Lactococcus lactis subsp. cremoris and Geotrichum candidum) and one thermophilic (Lactobacillus delbrueckii subsp. bulgaricus). The aim of this work was to study the stress responses of the food microbial consortium subjected to a freeze–thaw challenge (–20°C, 10 min / +25°C, 3 min) combined with physiological cryoadaptation (cryotolerance). Our results show that induction of cryotolerance by near-freezing temperature pretreatment of G. candidum and L. cremoris within the microbial community is similar to the one obtained with pure cultures. However, cryotolerance of L. bulgaricus was only induced within the consortium in milk. An interspecies cryoprotection was thus identified. This acquisition is correlated with the cell envelope extracts of G. candidum and/or the extracellular fractions of the two adapted mesophilic microorganisms. Therefore, in our experimental c...
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- 2005
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16. Horizontal Gene Transfer: A Universal Phenomenon
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Céline Chuiton and Jean-Michel Panoff
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Genetics ,Biological organism ,Mechanism (biology) ,Health, Toxicology and Mutagenesis ,Ecological Modeling ,fungi ,Computational biology ,Biology ,biology.organism_classification ,Pollution ,Genetically modified organism ,chemistry.chemical_compound ,chemistry ,Horizontal gene transfer ,Adaptation ,Gene ,DNA ,Bacteria - Abstract
According to the scientific literature, it is reasonable to consider that lateral transfer of genes is an usual mechanism of adaptation of the biological organisms to environmental stresses. Furthermore, from bacteria to cultured human cells, including fungi and plants, a large diversity of horizontal gene transfers—natural or artificial, experimental or deduced from sequence analysis—have been described. Therefore, the uncharacterized biodiversity—particularly in microbiology—associated with the universality of the horizontal gene transfer phenomenon leads to the consideration that dissemination of DNA from Genetically Modified Organisms (GMO) in biological environments, including food and soil, is uncontrolled and predictable.
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- 2004
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17. Le risque biologique : Une approche transdisciplinaire
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Jean-Michel Panoff and Jean-Michel Panoff
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Faut-il être biologiste ou biotechnologue pour avoir le privilège d'étudier le risque biologique? Juristes, sociologues, théologiens, paysans, historiens, psychologues nous avertissent : la biologie, avant tout science des'yeux', glisse insidieusement vers une science des'mains', de l'étude de la vie vers la manipulation du vivant. Voici une construction d'une pensée complexe autour de la question du risque biologique, question qui nécessite urgemment d'être collectivement posée.
- Published
- 2013
18. Cryoprotectants Lead to Phenotypic Adaptation to Freeze–Thaw Stress in Lactobacillus delbrueckii ssp. bulgaricus CIP 101027T
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Bouachanh Thammavongs, Jean-Michel Panoff, and Micheline Guéguen
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Cryopreservation ,Sucrose ,Osmotic shock ,Cryoprotectant ,food and beverages ,General Medicine ,Biology ,biology.organism_classification ,Adaptation, Physiological ,Trehalose ,General Biochemistry, Genetics and Molecular Biology ,Lactobacillus ,chemistry.chemical_compound ,Cryoprotective Agents ,Phenotype ,chemistry ,Biochemistry ,Freezing ,Cryoprotective Agent ,Glycerol ,Dimethyl Sulfoxide ,Lactose ,General Agricultural and Biological Sciences - Abstract
This study was conducted to investigate the ability of cryoprotective chemicals to induce phenotypic cryoadaptation in Lactobacillus delbrueckii ssp. bulgaricus CIP 101027T. Tolerance to negative temperature stress (freezing at -20 degrees C and thawing at 37 degrees C) was induced by pretreatment with Me(2)SO, glycerol, lactose, sucrose, and trehalose. Interestingly, Me(2)SO has a significantly greater cryoprotective effect than glycerol. Furthermore, lactose, sucrose, and trehalose, often referred to as osmotica, were shown to have greater cryoadaptive than cryoprotective properties. These results suggest that bacteria such as L. delbrueckii ssp. bulgaricus could be phenotypically adapted to freezing and thawing by an osmotic stress applied prior to freeze-thaw stress.
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- 2000
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19. Cryotolerance and cold stress in lactic acid bacteria
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Jean-Michel Panoff, Micheline Guéguen, and Bouachanh Thammavongs
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Cold tolerance ,Chemistry ,Cold resistance ,Environmental factor ,medicine ,Cold storage ,medicine.disease_cause ,Molecular biology ,Cold stress ,Food Science - Abstract
La maitrise des bacteries lactiques (LAB) impliquees dans le domaine agroalimentaire necessite une meilleure connaissance de leur comportement au froid (congelation des ferments, affinage a basse temperature positive, conservation des produits finis). L'etude des reponses au stress hypothermique chez les bacteries lactiques implique de devoir prendre en consideration : (i) le niveau d'abaissement de la temperature (positive ou negative), (ii) la duree de l'epreuve a basse temperature qui permet de distinguer un « choc d'une « acclimatation », (iii) les differents types thermiques. De plus, l'analyse de la connection entre le stress genere par le transfert des bacteries lactiques dans un environnement a basse temperature et la reponse qui lui est associee, engendre trois domaines d'investigation: (i) la reponse de la bacterie au plan physiologique (croissance et cryotolerance), (ii) les modifications biochimiques engendrees (degre de desaturation des acides gras et profil proteique), (iii) la mise en place des systemes de controle de la reponse. Les informations recentes en genetique moleculaire concernant les reponses au stress hypothermique des bacteries lactiques semblent insuffisamment correlees a une meilleure comprehension des phenomenes biochimiques ou physiologiques tels que la cryotolerance.
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- 2000
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20. Regulation of an Osmoticum-Responsive Gene in Anabaena sp. Strain PCC 7120
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Jean-Michel Panoff, Steven H. Schwartz, Todd A. Black, C. Peter Wolk, and Karin Jäger
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Transposable element ,Mutant ,Molecular Sequence Data ,Genetics and Molecular Biology ,Sodium Chloride ,Microbiology ,Open Reading Frames ,Bacterial Proteins ,Genes, Reporter ,Osmotic Pressure ,Genes, Regulator ,Amino Acid Sequence ,Molecular Biology ,DNA Primers ,Regulation of gene expression ,Genetics ,Reporter gene ,biology ,Base Sequence ,Sequence Homology, Amino Acid ,Genetic Complementation Test ,Gene Expression Regulation, Bacterial ,biology.organism_classification ,Anabaena ,Open reading frame ,Response regulator ,Mutagenesis, Insertional ,Genes, Bacterial ,Mutation ,DNA Transposable Elements ,bacteria ,Transposon mutagenesis ,Anabaena variabilis ,Plasmids - Abstract
Salt-induced genes in the cyanobacterium Anabaena sp. strain PCC 7120 were identified by use of a Tn 5 -based transposon bearing luxAB as a reporter. The genomic sequence adjacent to one site of insertion of the transposon was identical in part to the sequence of the lti2 gene, which was previously identified in a differential screen for cold-induced transcripts in Anabaena variabilis . The lti2 -like gene was induced by sucrose and other osmotica and by low temperature, in addition to salt. Regulatory components necessary for the induction of this gene by osmotica were sought by a further round of transposon mutagenesis. One mutant that displayed reduced transcriptional activity of the lti2 -like gene in response to exposure to osmotica had an insertion in an open reading frame, which was denoted orrA , whose predicted product showed sequence similarity to response regulators from two-component regulatory systems. The corresponding mutation was reconstructed and was shown, like the second-site transposon mutation, to result in reduced response to osmotic stress. Induction of the lux reporter gene by osmotica was restored by complementation with a genomic fragment containing the entire open reading frame for the presumptive response regulator, whereas a fragment containing a truncated copy of the open reading frame for the response regulator did not complement the mutation.
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- 1998
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21. Cryotolerance and Cold Adaptation in Lactococcus lactis Subsp. lactis IL1403
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Jean-Marie Laplace, Yanick Auffray, Philippe Boutibonnes, Bouachanh Thammavongs, Axel Hartke, and Jean-Michel Panoff
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Lactococcus lactis subsp. lactis ,Chaotropic agent ,Biochemistry ,Chemical treatment ,Cold adaptation ,Lactococcus lactis ,General Medicine ,Biology ,General Agricultural and Biological Sciences ,biology.organism_classification ,Streptococcaceae ,General Biochemistry, Genetics and Molecular Biology ,Bacteria - Abstract
The physiology of the cold-shock response in Lactococcus lactis subsp. lactis IL1403 at a subzero temperature, and cold-induced adaptation to heat shock, were investigated. Preincubation of cells at 8°C led to the development of cryotolerance, i.e., an enhanced capacity to survive exposure to freezing temperature (-20°C). Pretreatment with chemicals considered to be chaotropic agents did not induce cryotolerance or, in contrast, led to a decrease in survival capacity at -20°C. Interestingly, preincubation at 8°C led also to thermololerance to a 52°C challenge, but preincubation of cells at 42°C for 30 min did not improve their capacity to survive freezing-thawing exposure. These results demonstrate that cold- and heat-shock responses are physiologically linked by a complex relation. Furthermore, food processing at low temperature before subzero or heat treatment may need to be reconsidered.
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- 1995
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22. Effects of Roundup® and Glyphosate on Three Food Microorganisms: Geotrichum candidum, Lactococcus lactis subsp. cremoris and Lactobacillus delbrueckii subsp. bulgaricus
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Caroline Amiel, Gilles-Eric Séralini, Emilie Clair, Laura Linn, Jean-Michel Panoff, Carine Travert, Œstrogènes, reproduction, cancer (OeReCa), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Aliments Bioprocédés Toxicologie Environnements (ABTE), Normandie Université (NU)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), 'Committee for Independent Information and Research on Genetic Engineering, Comité de Recherche et d’Information Indépendantes sur le génie Génétique (CRIIGEN), and Microorganismes d'Intérêt Laitier et Alimentaire (MILA)
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Glycine ,Geotrichum ,010501 environmental sciences ,01 natural sciences ,Applied Microbiology and Biotechnology ,Microbiology ,03 medical and health sciences ,chemistry.chemical_compound ,Lactobacillus ,[SDV.BC.IC]Life Sciences [q-bio]/Cellular Biology/Cell Behavior [q-bio.CB] ,Food microbiology ,Animals ,Food science ,0105 earth and related environmental sciences ,2. Zero hunger ,0303 health sciences ,Lactobacillus delbrueckii ,biology ,030306 microbiology ,business.industry ,Herbicides ,Lactococcus lactis subsp cremoris ,Lactococcus lactis ,food and beverages ,[SDV.BBM.BM]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Molecular biology ,General Medicine ,Raw milk ,biology.organism_classification ,Biotechnology ,Milk ,chemistry ,13. Climate action ,Glyphosate ,Food Microbiology ,Cattle ,business ,Lactobacillus delbrueckii subsp. bulgaricus - Abstract
International audience; Use of many pesticide products poses the problem of their effects on environment and health. Amongst them, the effects of glyphosate with its adjuvants and its by-products are regularly discussed. The aim of the present study was to shed light on the real impact on biodiversity and ecosystems of Roundup(®), a major herbicide used worldwide, and the glyphosate it contains, by the study of their effects on growth and viability of microbial models, namely, on three food microorganisms (Geotrichum candidum, Lactococcus lactis subsp. cremoris and Lactobacillus delbrueckii subsp. bulgaricus) widely used as starters in traditional and industrial dairy technologies. The presented results evidence that Roundup(®) has an inhibitory effect on microbial growth and a microbicide effect at lower concentrations than those recommended in agriculture. Interestingly, glyphosate at these levels has no significant effect on the three studied microorganisms. Our work is consistent with previous studies which demonstrated that the toxic effect of glyphosate was amplified by its formulation adjuvants on different human cells and other eukaryotic models. Moreover, these results should be considered in the understanding of the loss of microbiodiversity and microbial concentration observed in raw milk for many years.
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- 2012
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23. Proteomic expression of microfungal ripening starter Geotrichum candidum submitted to cold stress is strain-dependent: studies using 2d-dige technology and samespots software analysis
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Ghalia, Missous, Bouachanh, Thammavongs, Virginie, Dieuleveux, Maryline, Houssin, Joël, Henry, Jean-Michel, Panoff, Panoff, Jean-Michel, Microorganismes d'Intérêt Laitier et Alimentaire (MILA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Centre de recherche en gestion (CRG), and École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS)
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Cold Temperature ,Fungal Proteins ,Proteomics ,[SDV] Life Sciences [q-bio] ,Stress, Physiological ,[SDV]Life Sciences [q-bio] ,Electrophoresis, Gel, Two-Dimensional ,Carbocyanines ,Geotrichum ,Software ,Fluorescent Dyes - Abstract
International audience; Geotrichum candidum is a micro-fungus widely used as a ripening starter in cheese making. In anthropogenic environments such as dairy industries, this microorganism is subjected to many environmental and technological stresses including low temperature exposure. Our aim was to study the proteomic response of G. candidum to cold stress using a comparative proteomic approach by two-dimensional Differential In Gel Electrophoresis (2D DIGE). This technique consists on the labeling of proteins by specific fluorescent dyes (CyDyes). The results, obtained with G. candidum cells subjected to cold temperature, show significant proteomic patterns differences compared with the standard conditions. Furthermore, this biochemical response seems strain specific. 2D DIGE technology combined with SameSpots™ software analysis support these results through an important statistical validity. The comparative studies in a single gel, using two different fluorescent CyDyes (Cy3 and Cy5), lead to proteins differentiation. Selected spots were treated and analyzed by mass spectrometry.
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- 2012
24. The cold shock response inLactococcus lactis subsp.lactis
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Jean-Michel Panoff, Bouachanh Thammavongs, Stéphane Legrand, and Philippe Boutibonnes
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Gel electrophoresis ,Strain (chemistry) ,Lactococcus lactis ,General Medicine ,Gel electrophoresis of proteins ,Biology ,biology.organism_classification ,Streptococcaceae ,Applied Microbiology and Biotechnology ,Microbiology ,Lactic acid ,Cold shock response ,chemistry.chemical_compound ,chemistry ,Biochemistry ,Bacteria - Abstract
The lactic acid bacterium,Lactococcus lactis subsp.lactis IL1403 was subjected to defferent cold temperatures for various times. Physiological experiments showed that this strain had an improved survival capacity in stationary phase as the temperature decreased. Two-dimensional electrophoresis of proteins extracted from cold-temperature exposed cultures showed that a dozen proteins are overexpressed up to threefold compared with exposure at 30°C. Most of these proteins are overexpressed first, temporarily and second, in the first 10 h after the transfer to 8°C. These observations indicate that response to cold stress inL. lactis subsp.lactis is an active phenomenon.
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- 1994
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25. Response to environmental stress as a global phenomenon in biology: the example of microorganisms
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Emmanuel Denou, Bouachanh Thammavongs, Micheline Guéguen, Ghalia Missous, and Jean-Michel Panoff
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Abiotic component ,Ecology ,Abiotic stress ,Microorganism ,fungi ,Anthropogenic pressure ,food and beverages ,Soil Science ,Adaptive response ,Plant Science ,General Medicine ,Biotic stress ,Biology ,Environmental stress ,Stress (mechanics) ,Ecology, Evolution, Behavior and Systematics - Abstract
Any modification of the environment that leads to a physiological, genetic, or epigenetic adaptive response in microorganisms may be considered as a stress. Historically, forms of stresses affecting biological structures were classified either as non-thermal, such as osmotic, oxidative, or acid stress or as thermal stress, hot or cold. Currently, the classification in biology is as abiotic, including physical and chemical stress, or biotic. The aim of this mini-review is to show, through the example of microorganisms, that the response to stress can be considered, in biology, as a global phenomenon, which can be extended to anthropogenic pressure.
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- 2011
26. Control of a locus that is required for growth ofAnabaena PCC7120 at low temperature
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Jean-Michel Panoff
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Transposable element ,Thermal shock ,biology ,Anabaena ,Mutant ,Repressor ,General Medicine ,biology.organism_classification ,Applied Microbiology and Biotechnology ,Microbiology ,Ribosome ,Biophysics ,Luminescence ,Bacteria - Abstract
Mutant TLT2, obtained by insertion of alux-bearing transposon inAnabaena sp. strain PCC7120, increases in luminescent intensity when transferred from 30° to 20°C. The addition of different types of antibiotics to the culture medium showed that some of those known to have the ribosome as target led to an increase of luminescence of TLT2 at 30°C, in accord with the idea that ribosomes may be sensors of cold shock. Furthermore, rifampicin, which destabilized luminescence at 20°C, decreased the rate of loss of luminescence upon transfer of TLT2 from 20° to 30°C; this suggests that luminescence of TLT2 is transcriptionally controlled by a repressor at 30°C.
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- 1993
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27. Identification of genes associated with the long-gut-persistence phenotype of the probiotic Lactobacillus johnsonii strain NCC533 using a combination of genomics and transcriptome analysis
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Bernard Berger, Raymond David Pridmore, Harald Brüssow, Fabrizio Arigoni, Jean-Michel Panoff, and Emmanuel Denou
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Genomics and Proteomics ,Operon ,Mice, Inbred Strains ,Microbiology ,Transcriptome ,Mice ,Animals ,Molecular Biology ,Gene ,Lactobacillus johnsonii ,Genetics ,Strain (chemistry) ,biology ,Microarray analysis techniques ,Gene Expression Profiling ,Probiotics ,Polysaccharides, Bacterial ,Chromosome Mapping ,Genomics ,biology.organism_classification ,Phenotype ,Gene expression profiling ,Lactobacillus ,Jejunum ,Genes, Bacterial ,Gene Deletion - Abstract
Lactobacillus johnsonii strains NCC533 and ATCC 33200 (the type strain of this species) differed significantly in gut residence time (12 versus 5 days) after oral feeding to mice. Genes affecting the long gut residence time of the probiotic strain NCC533 were targeted for analysis. We hypothesized that genes specific for this strain, which are expressed during passage of the bacterium through the gut, affect the phenotype. When the DNA of the type strain was hybridized against a microarray of the sequenced NCC533 strain, we identified 233 genes that were specific for the long-gut-persistence isolate. Whole-genome transcription analysis of the NCC533 strain using the microarray format identified 174 genes that were strongly and consistently expressed in the jejunum of mice monocolonized with this strain. Fusion of the two microarray data sets identified three gene loci that were both expressed in vivo and specific to the long-gut-persistence isolate. The identified genes included LJ1027 and LJ1028, two glycosyltransferase genes in the exopolysaccharide synthesis operon; LJ1654 to LJ1656, encoding a sugar phosphotransferase system (PTS) transporter annotated as mannose PTS; and LJ1680, whose product shares 30% amino acid identity with immunoglobulin A proteases from pathogenic bacteria. Knockout mutants were tested in vivo. The experiments revealed that deletion of LJ1654 to LJ1656 and LJ1680 decreased the gut residence time, while a mutant with a deleted exopolysaccharide biosynthesis cluster had a slightly increased residence time.
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- 2008
28. Gene Expression of Commensal Lactobacillus johnsonii Strain NCC533 during In Vitro Growth and in the Murine Gut▿
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Caroline Barretto, Jean-Michel Panoff, Emmanuel Denou, Harald Brüssow, Bernard Berger, and Fabrizio Arigoni
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biology ,Genomics and Proteomics ,Transcription, Genetic ,Gene Expression Profiling ,Gene Expression Regulation, Bacterial ,biology.organism_classification ,Microbiology ,Molecular biology ,Gene expression profiling ,Transcriptome ,Gastrointestinal Tract ,Lactobacillus ,Mice ,Plasmid ,In vivo ,Gene expression ,Animals ,Molecular Biology ,Gene ,Lactobacillus johnsonii ,Oligonucleotide Array Sequence Analysis - Abstract
Work with pathogens like Vibrio cholerae has shown major differences between genes expressed in bacteria grown in vitro and in vivo. To explore this subject for commensals, we investigated the transcription of the Lactobacillus johnsonii NCC533 genome during in vitro and in vivo growth using the microarray technology. During broth growth, 537, 626, and 277 of the 1,756 tested genes were expressed during exponential phase, “adaptation” (early stationary phase), and stationary phase, respectively. One hundred one, 150, and 33 genes, respectively, were specifically transcribed in these three phases. To explore the in vivo transcription program, we fed L. johnsonii containing a resistance plasmid to antibiotic-treated mice. After a 2-day washout phase, we determined the viable-cell counts of lactobacilli that were in the lumina and associated with the mucosae of different gut segments. While the cell counts showed a rather uniform distribution along the gut, we observed marked differences with respect to the expression of the Lactobacillus genome. The largest number of transcribed genes was in the stomach ( n = 786); the next-largest numbers occurred in the cecum ( n = 391) and the jejunum ( n = 296), while only 26 Lactobacillus genes were transcribed in the colon. In vitro and in vivo transcription programs overlapped only partially. One hundred ninety-one of the transcripts from the lactobacilli in the stomach were not detected during in vitro growth; 202 and 213 genes, respectively, were transcribed under all in vitro and in vivo conditions; but the core transcriptome for all growth conditions comprised only 103 genes. Forty-four percent of the NCC533 genes were not detectably transcribed under any of the investigated conditions. Nontranscribed genes were clustered on the genome and enriched in the variable-genome part. Our data revealed not only major differences between in vitro- and in vivo-expressed genes in a Lactobacillus gut commensal organism but also marked changes in the expression of genes along the digestive tract.
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- 2007
29. Procédure de gestion des collections et modes opératoires de congélation des microorganismes d'intérêt laitier
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Catherine Denis, Joëlle Reitz-Ausseur, Jean-François Chamba, Serge Casaregola, Anne Thierry, Catherine Beal, Abraham L., Callon C.H.D., Ferey C., Emmanuel Jamet, Marie-Christine Montel, Ogier, J. C., Jean-Michel Panoff, Sahi A., Valérie Stahl, AgroParisTech, Paris-Saclay Food and Bioproduct Engineering (SayFood), AgroParisTech-Université Paris-Saclay-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), INRAE Université Clermont Auvergne, and Arilait Recherche
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[SDV]Life Sciences [q-bio] ,[SDV.IDA]Life Sciences [q-bio]/Food engineering ,ComputingMilieux_MISCELLANEOUS - Abstract
International audience
- Published
- 2007
30. Congélation de micro-organismes d'intérêt laitier : optimisation des conditions d'adaptation des souches avant congélation et des conditions de remise en culture après congélation
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Catherine Denis, Catherine Beal, Marielle Bouix, Jean-François Chamba, Emmanuel Jamet, Jean-Claude Ogier, Jean-Michel Panoff, Aline Rault, Bouachanh Thammavongs, Anne Thierry, Association pour le Développement de la Recherche Appliquée aux Industries Agricoles et Alimentaires, Génie et Microbiologie des Procédés Alimentaires (GMPA), Institut National de la Recherche Agronomique (INRA)-AgroParisTech, AgroParisTech, Ecole Nationale Supérieure des Industries Agricoles et Alimentaires, Institut Technique Français des Fromages (ITFF), Ecologie microbienne des insectes et interactions hôte-pathogène (EMIP), Université Montpellier 2 - Sciences et Techniques (UM2)-Institut National de la Recherche Agronomique (INRA), Microorganismes d'Intérêt Laitier et Alimentaire (MILA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Science et Technologie du Lait et de l'Oeuf (STLO), Institut National de la Recherche Agronomique (INRA)-AGROCAMPUS OUEST, Institut National de la Recherche Agronomique (INRA)-Université Montpellier 2 - Sciences et Techniques (UM2), and Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)-Institut national d'enseignement supérieur pour l'agriculture, l'alimentation et l'environnement (Institut Agro)
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PRODUIT LAITIER ,CONGELATION ,LACTOBACILLE THERMOPHILE ,[SDV.GEN]Life Sciences [q-bio]/Genetics ,CRYOPRESERVATION ,CONSERVATION IN SITU - Abstract
Congélation de micro-organismes d'intérêt laitier : optimisation des conditions d'adaptation des souches avant congélation et des conditions de remise en culture après congélation
- Published
- 2006
31. Resin straw as an alternative system to securely store frozen microorganisms
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Jean-Michel Panoff, Bouachanh Thammavongs, Nathalie Desmasures, Jean-Marc Poncet, Micheline Guéguen, Microorganismes d'Intérêt Laitier et Alimentaire (MILA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Institut Français de Recherche pour l'Exploitation de la Mer - Brest (IFREMER Centre de Bretagne), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER), and Normandie Université (NU)
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Microbiological Techniques ,Microbiology (medical) ,MESH: Cold Temperature ,Lactococcus ,Microorganism ,Colony Count, Microbial ,Context (language use) ,Geotrichum ,Polypropylenes ,Microbiology ,03 medical and health sciences ,Lactobacillus ,Freezing ,Botany ,MESH: Cryopreservation ,Food science ,Molecular Biology ,MESH: Colony Count, Microbial ,[SDV.MP.MYC]Life Sciences [q-bio]/Microbiology and Parasitology/Mycology ,030304 developmental biology ,Cryopreservation ,0303 health sciences ,Polycarboxylate Cement ,biology ,030306 microbiology ,Lactococcus lactis ,food and beverages ,MESH: Microbiological Techniques ,Straw ,MESH: Polypropylenes ,biology.organism_classification ,[SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology ,Cold Temperature ,MESH: Geotrichum ,MESH: Lactococcus lactis ,MESH: Polycarboxylate Cement ,MESH: Lactobacillus ,[SDV.AEN]Life Sciences [q-bio]/Food and Nutrition ,Bacteria ,MESH: Freezing - Abstract
International audience; Freezing of prokaryotic and eukaryotic microorganisms is the main interest in the study of cold stress responses of living organisms. In parallel, applications which arise from this approach are of two types: (i) optimization of the frozen starters used in food processing; and (ii) improvement of the ex situ preservation of microorganisms in collections. Currently, cryopreservation of microorganisms in collections is carried out in cryotubes, and bibliographical references related to freezing microorganisms packaged in straws are scarce. In this context, a preliminary study was completed to evaluate the technological potential of ionomeric resin straws compared to polycarbonate cryo-tubes. Survival under freezing stress was tested on three microorganisms selected for their biotechnological interest: two lactic acid bacteria, Lactococcus lactis subsp. cremoris and Lactobacillus delbrueckii subsp. bulgaricus and a deuteromycete fungus, Geotrichum candidum. The stress was carried out by repeated freezing-thawing cycles to artificially accelerate the lethal effect of freezing on the microorganisms. Two main results were obtained: (i) the survival rate values (per freezing-thawing cycle) seems to depend on the thermal type of the studied microorganism, and (ii) there was no, under our experimental conditions, significant difference between straws and tubes. However, conservation in the resin straws lead to a slight increase in the survival of L. cremoris and G. candidum compared to microtubes. In those conditions, straws seems an alternative system to securely store frozen microorganisms with three main characteristics: (i) a high resistance to thermal stress, (ii) a safe closing by hermetic weld, and (iii) a system for inviolable identification.
- Published
- 2004
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32. Nystatin and osmotica as chemical enhancers of the phenotypic adaptation to freeze-thaw stress in Geotrichum candidum ATCC 204307
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Jean-Michel Panoff, Bouachanh Thammavongs, Ségolène Dubernet, and Micheline Guéguen
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Cryopreservation ,Nystatin ,Fermentation starter ,Antifungal Agents ,biology ,Osmotic shock ,Geotrichum ,Cheese ripening ,Ripening ,General Medicine ,Fungi imperfecti ,biology.organism_classification ,Microbiology ,Adaptation, Physiological ,Cold Temperature ,Phenotype ,Freezing ,medicine ,Inducer ,Food science ,Food Science ,medicine.drug - Abstract
Geotrichum candidum is a yeast-like fungus used as ripening starter in cheese making. The present study focused on chemical stress pretreatments affecting survival of G. candidum ATCC 204307 to freeze-thaw stress. Cryotolerance of G. candidum cells was induced by pretreatment with NaCl, CaCl2, or MgCl2, indicating heterologous phenotypic adaptation to freeze-thaw stress (- 20 to 25 degrees C) by osmotic stress. Furthermore, the nystatin, an antifungal compound, was shown to be a cryotolerance inducer.
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- 2002
33. Intra-species chromosome-length polymorphism in Geotrichum candidum revealed by pulsed field gel electrophoresis
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Nathalie Desmasures, Martine Beliard, Jean-Michel Panoff, Ghislaine Plessis, Stéphanie Gente, Micheline Guéguen, Cyril Jacopin, Laboratoire de Microbiologie Alimentaire (LMA), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Institut National de la Recherche Agronomique (INRA), Service de Génétique [CHU Caen], CHU Caen, Normandie Université (NU)-Tumorothèque de Caen Basse-Normandie (TCBN)-Normandie Université (NU)-Tumorothèque de Caen Basse-Normandie (TCBN)-Université de Caen Normandie (UNICAEN), Normandie Université (NU), Normandie Université (NU)-Normandie Université (NU)-CHU Caen, and Normandie Université (NU)-Tumorothèque de Caen Basse-Normandie (TCBN)-Tumorothèque de Caen Basse-Normandie (TCBN)
- Subjects
DNA, Bacterial ,Geotrichum ,Biology ,MESH: Genome, Bacterial ,Microbiology ,Genome ,03 medical and health sciences ,Geotrichosis ,Species Specificity ,MESH: Polymorphism, Genetic ,medicine ,Pulsed-field gel electrophoresis ,MESH: Species Specificity ,Genome size ,[SDV.MP.MYC]Life Sciences [q-bio]/Microbiology and Parasitology/Mycology ,030304 developmental biology ,2. Zero hunger ,Gel electrophoresis ,Genetics ,0303 health sciences ,Polymorphism, Genetic ,030306 microbiology ,Chromosome ,Karyotype ,General Medicine ,medicine.disease ,biology.organism_classification ,MESH: DNA, Bacterial ,Electrophoresis, Gel, Pulsed-Field ,MESH: Geotrichum ,MESH: Electrophoresis, Gel, Pulsed-Field ,[SDV.AEN]Life Sciences [q-bio]/Food and Nutrition ,Genome, Bacterial ,Food Science - Abstract
International audience; Geotrichum candidum is an ascomycetous anamorph yeast-like fungus found in various habitats. It is a component of the natural flora of milk and is used as a maturing agent for both soft and hard cheeses. This microorganism displays phenotypic variability and may act as an opportunist pathogen, causing geotrichosis. Cytological analysis of G. candidum strain ATCC 204307 showed this strain to have eight chromosomes. We prepared chromosomal DNA from 13 strains of G. candidum differing in habitat and morphotype. We used pulsed field gel electrophoresis (PFGE) in two sets of conditions to determine the size of the chromosomal DNA molecules. The strains investigated had five to eight chromosomes, 0.6 to 4.5 Mb in size. We estimated genome size in these 13 strains to be between 11 and 19 Mb. Pulsed-field gel electrophoresis profiles showed a high degree of polymorphism, indicating considerable variability between strains. Genome size and the presence of large chromosomes appeared to be correlated with morphotype. Strains with a mold-like or intermediate morphotype tended to have larger genomes than strains with a yeast-like morphotype did.
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- 2002
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34. Genetic diversity among Geotrichum candidum strains from various substrates studied using RAM and RAPD-PCR
- Author
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Micheline Guéguen, Nathalie Desmasures, Stéphanie Gente, Jean-Michel Panoff, Université de Caen Normandie (UNICAEN), and Normandie Université (NU)
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education ,Geotrichum ,Applied Microbiology and Biotechnology ,Polymerase Chain Reaction ,law.invention ,MESH: Random Amplified Polymorphic DNA Technique ,03 medical and health sciences ,Feces ,law ,parasitic diseases ,Environmental Microbiology ,Animals ,Humans ,MESH: Genetic Variation ,MESH: Food Microbiology ,DNA, Fungal ,Polymerase chain reaction ,[SDV.MP.MYC]Life Sciences [q-bio]/Microbiology and Parasitology/Mycology ,030304 developmental biology ,2. Zero hunger ,Genetics ,Ecological niche ,0303 health sciences ,Genetic diversity ,biology ,030306 microbiology ,technology, industry, and agriculture ,Genetic Variation ,MESH: Environmental Microbiology ,MESH: Polymerase Chain Reaction ,General Medicine ,Fungi imperfecti ,15. Life on land ,biology.organism_classification ,RAPD ,Random Amplified Polymorphic DNA Technique ,MESH: DNA, Fungal ,MESH: Geotrichum ,Taxon ,Agro food ,Food Microbiology ,Cattle ,Female ,human activities ,[SDV.AEN]Life Sciences [q-bio]/Food and Nutrition ,Biotechnology - Abstract
Aims: Assessment of genetic diversity within the species Geotrichum candidum and development of tools to trace the strains that play an important role in the agro food industry. Methods and Results: RAM-PCR and RAPD-PCR techniques were assessed for their ability to discriminate 57 strains of various morphotypes, substrates and geographical origin. The techniques were complementary and, when combined, allowed us to discriminate isolates. Moreover, we established a link between a taxon and its occupation of an ecological niche, which should not be confused with the substrate of isolation. Conclusions: We observed a high degree of diversity, which could be linked to the variety of the ecological niches chosen and to the high degree of morphological polymorphism encountered within the species. Significance and Impact of the Study: Used in combination, RAM-PCR and RAPD-PCR permit traceability and monitoring systems for G. candidum strains during food processing.
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- 2002
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35. In situ protection of microbiodiversity is under consideration
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Jean-Michel Panoff, Micheline Guéguen, Bouachanh Thammavongs, Nathalie Desmasures, Université de Caen Normandie (UNICAEN), and Normandie Université (NU)
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In situ ,Conservation of Natural Resources ,0303 health sciences ,030306 microbiology ,Biology ,Microbiology ,Data science ,[SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology ,MESH: Milk ,03 medical and health sciences ,MESH: Lactococcus ,Milk ,Lactococcus ,MESH: Microbiology ,MESH: Conservation of Natural Resources ,Animals ,Humans ,MESH: Ecosystem ,[SDV.AEN]Life Sciences [q-bio]/Food and Nutrition ,Ecosystem ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology - Abstract
International audience
- Published
- 2002
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36. Phenotypic adaptation to freeze-thaw stress of the yeast-like fungus Geotrichum candidum
- Author
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Bouachanh Thammavongs, Jean-Michel Panoff, and Micheline Guéguen
- Subjects
Arrhenius equation ,Fermentation starter ,Time Factors ,biology ,Geotrichum ,General Medicine ,Activation energy ,biology.organism_classification ,Microbiology ,Adaptation, Physiological ,Yeast ,Stress (mechanics) ,Cold Temperature ,symbols.namesake ,Phenotype ,Botany ,Congelation ,Freezing ,symbols ,Food Microbiology ,Growth rate ,Food science ,Food Science - Abstract
The effect of cold stress on Geotrichum candidum was investigated at chill and freezing temperatures. Specific growth rates were determined at various temperatures and plotted according to the Ratkowsky and Arrhenius equations. The obtained profiles led to the determination of characteristics including the activation energy and notional minimum temperatures. At temperatures below the optimum single linear slopes were observed. At freezing temperatures, the loss of viability of cell populations was proportional to the number of freezing-thawing cycles. Nevertheless, the ability of G. candidum to survive this challenge depended on the physiological conditions prior to the freezing stress. The loss of viability was growth phase specific. Cells harvested in stationary phase showed a higher resistance compared to those obtained with cells in exponential phase. Furthermore, the cells of G. candidum could be adapted to the freeze-thaw challenge by pre-treatment at chill temperatures. This phenomenon known as cryotolerance was a function of the duration of the preincubation exposure.
- Published
- 2000
37. Cold stress responses in mesophilic bacteria
- Author
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Micheline Guéguen, Philippe Boutibonnes, Bouachanh Thammavongs, and Jean-Michel Panoff
- Subjects
Cryobiology ,biology ,General Medicine ,Metabolism ,Bacterial Physiological Phenomena ,biology.organism_classification ,General Biochemistry, Genetics and Molecular Biology ,Cold shock response ,Cold Temperature ,Biochemistry ,General Agricultural and Biological Sciences ,Cold stress ,Bacteria ,Mesophile ,Fatty acid desaturation - Abstract
The diversity of the prokaryotes that have been studied, combined with the many different effects of low temperature, has led to an extensive literature concerning cold stress responses in mesophilic bacteria. The aim of this review is to discuss the effects of cold on the behavior of bacteria. The following three responses will be described: (i) biochemical modifications consisting first of membrane fatty acid desaturation and second of the synthesis of cold stress proteins, (ii) physiological responses of the cells to permit growth at low temperatures above 0 degrees C and cryotolerance at lower temperatures, and (iii) control of the cold shock response at a transcriptional and/or translational level. This paper reviews knowledge, most of which has been acquired in the last 10 years, in the field of cold stress responses. It is hoped that these data will help to focus attention on the metabolic responses associated with environmental disturbance.
- Published
- 1998
38. Lacks and possible improvements in European Union law concerning GMOs
- Author
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Jean-Michel Panoff, Marie-Pierre Baudin-Maurin, Centre de recherche en droit privé (CRDP), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Aliments Bioprocédés Toxicologie Environnements (ABTE), Normandie Université (NU)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), and Normandie Université (NU)
- Subjects
Sustainable development ,European Union law ,Engineering ,sustainable development ,Multidisciplinary ,GMO ,Parliament ,business.industry ,media_common.quotation_subject ,Genetically modified microorganisms ,Legislation ,Directive ,European law ,Genetically modified organism ,Biotechnology ,[SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology ,Regulation of genetic engineering ,13. Climate action ,genetically modified organism ,business ,risk ,media_common ,Law and economics - Abstract
International audience; Because of the complexity of many environmental problems, we need their holistic assessment. That is why, in such a matter, a multidisciplinary approach is necessary. It has also been the guiding line for this present study on the European regulation of the GMOs, crossing the different points of view of a lawyer and a biologist. According to the European legislation, molecular biology and dissemination of genetically modified organisms are mainly regulated by two major directives of the European Parliament and of the Council: Directive 2009/41/EC on the contained use of genetically modified microorganisms, and Directive 2001/18/EC on the deliberate release into the environment of genetically modified organisms. Two different approaches are possible to analyse those directives and suggest possible improvements.
- Published
- 2014
- Full Text
- View/download PDF
39. Differentiation between cold shock proteins and cold acclimation proteins in a mesophilic gram-positive bacterium, Enterococcus faecalis JH2-2
- Author
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Philippe Boutibonnes, Jean-Michel Panoff, D. Corroler, Bouachanh Thammavongs, Aliments Bioprocédés Toxicologie Environnements (ABTE), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), and Normandie Université (NU)
- Subjects
0303 health sciences ,biology ,030306 microbiology ,Gram-positive bacteria ,[SDV]Life Sciences [q-bio] ,Prokaryote ,Cold-shock domain ,biology.organism_classification ,Microbiology ,[SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology ,Enterococcus faecalis ,Bacterial protein ,Cold Temperature ,03 medical and health sciences ,Kinetics ,[SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology ,Bacterial Proteins ,Cold acclimation ,Electrophoresis, Gel, Two-Dimensional ,Molecular Biology ,030304 developmental biology ,Mesophile ,Research Article - Abstract
International audience; Transfer of Enterococcus faecalis to a cold temperature (8 degrees C for 4 to 30 h) led to increased expression of 11 cold shock proteins (CSPs). Furthermore, this mesophilic prokaryote synthesized 10 cold acclimation proteins, five of them distinct from CSPs, during continuous growth (4 days) at the same temperature (8 degrees C).
- Published
- 1997
- Full Text
- View/download PDF
40. Physiological response of Enterococcus faecalis JH2-2 to cold shock: growth at low temperatures and freezing/thawing challenge
- Author
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Bouachanh Thammavongs, D. Corroler, Jean-Michel Panoff, Yanick Auffray, Philippe Boutibonnes, Aliments Bioprocédés Toxicologie Environnements (ABTE), Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU)-Université de Rouen Normandie (UNIROUEN), Normandie Université (NU), Laboratoire de Microbiologie de l’Environnement (LME), Institut National de la Recherche Agronomique (INRA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Normandie Université (NU)-Normandie Université (NU)-Institut National de la Recherche Agronomique (INRA), and CORROLER, David
- Subjects
Time Factors ,Freezing thawing ,Colony Count, Microbial ,Applied Microbiology and Biotechnology ,Models, Biological ,Enterococcus faecalis ,Degree (temperature) ,Microbiology ,Incubation period ,03 medical and health sciences ,symbols.namesake ,Animal science ,Freezing ,[SDV.MP] Life Sciences [q-bio]/Microbiology and Parasitology ,030304 developmental biology ,Arrhenius equation ,0303 health sciences ,Shock (fluid dynamics) ,biology ,030306 microbiology ,biology.organism_classification ,[SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology ,Cold Temperature ,[SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology ,symbols ,Positive temperature ,Phenotypic resistance ,Stress, Mechanical ,[SDV.MP.BAC] Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology - Abstract
International audience; Growth at low positive temperatures and induced phenotypic resistance to extreme cold temperature (freezing/thawing cycles) of Enterococcus faecalis were investigated. The effect of low temperatures on the specific growth rates was studied; use of Arrhenius profile and Ratkovsky 'square-root' model allowed determination of the 'temperature characteristic' (mu approximately equal to 13,800 cal mol-1), the critical temperature (Tcrit approximately equal to 17.9 degrees C) and the notional minimum growth temperature (T0 approximately equal to 3.6 degrees C). Preincubation of Ent. faecalis cells at low temperatures (8-16 degrees C) during periods corresponding to their generation time resulted in an increased ability of the bacterial cells to withstand short periods of freezing/thawing (-20 degrees C/+37 degrees C) challenge. Moreover, the increase of the incubation period at low positive temperature led to a higher degree of adaptation.
- Published
- 1996
41. Induction of thermotolerance by chemical agents in Lactococcus lactis subsp. lactis IL1403
- Author
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Bouachanh Thammavongs, V. Bisson, Yanick Auffray, Abdellah Benachour, Jean-Michel Panoff, Axel Hartke, Philippe Boutibonnes, Université de Caen Normandie (UNICAEN), Normandie Université (NU), Université Djillali Liabes [Sidi Bel Abbès], Laboratoire de Microbiologie de l’Environnement (LME), Institut National de la Recherche Agronomique (INRA)-Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Université Djilali Liabès [Sidi-Bel-Abbès], and Normandie Université (NU)-Normandie Université (NU)-Institut National de la Recherche Agronomique (INRA)
- Subjects
Azides ,Hot Temperature ,[SDV]Life Sciences [q-bio] ,Cadmium chloride ,medicine.disease_cause ,Microbiology ,03 medical and health sciences ,chemistry.chemical_compound ,Cadmium Chloride ,Chlorides ,Heat shock protein ,medicine ,[SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology ,Sodium Azide ,Escherichia coli ,Heat-Shock Proteins ,ComputingMilieux_MISCELLANEOUS ,030304 developmental biology ,Mercaptoethanol ,0303 health sciences ,biology ,030306 microbiology ,Lactococcus lactis ,Temperature ,General Medicine ,biology.organism_classification ,Streptococcaceae ,GroEL ,Adaptation, Physiological ,Methylene Blue ,chemistry ,Biochemistry ,Mercuric Chloride ,Sodium azide ,Bacteria ,Food Science ,Cadmium - Abstract
Like in other organisms tested to date, adapted cells of Lactococcus lactis subsp. lactis IL1403 pretreated at 42 °C for 30 min develop a thermotolerant state i.e. an increased ability to survive subsequent exposure to a lethal challenge temperature (52 °C for 15 or 30 min). In different cellular systems, chemicals as diverse as divalent metal salts, natural or synthetic compounds trigger the development of thermotolerance. Yet, in L. lactis subsp. lactis IL1403, among the 17 chemicals tested, only four induced this transient increased tolerance to heat: cadmium chloride, mercury chloride, sodium azide and β-mercaptoethanol. Intriguingly, none of these four compounds induced the synthesis of three major heat shock proteins (DnaK, GroEL and hsp104-analogue), which are believed to be responsible for thermotolerance in most organisms. It is suggested that: (i) the lesions produced by these various ‘proteotoxic’ agents are fundamentally different from those produced by heat; (ii) heat shock protein synthesis and transient induced tolerance to heat are not tightly correlated phenomena in L. lactis subsp. lactis as they are in Escherichia coli and some other organisms.
- Published
- 1995
- Full Text
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42. Cold Shock Response and Adaptation
- Author
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Jean Michel Panoff
- Subjects
General Medicine ,Adaptation ,Biology ,General Agricultural and Biological Sciences ,Neuroscience ,General Biochemistry, Genetics and Molecular Biology ,Cold shock response - Published
- 2001
- Full Text
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43. Synthesis of nitrogenase in mutants of the cyanobacterium Anabaena sp. strain PCC 7120 affected in heterocyst development or metabolism
- Author
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Jean-Michel Panoff, Y Cai, Todd A. Black, C P Wolk, D N Tiwari, and A Ernst
- Subjects
Cyanobacteria ,Nitrogen ,Mutant ,Blotting, Western ,Biology ,Microbiology ,Gene Expression Regulation, Enzymologic ,Oxygen Consumption ,Enzyme Stability ,Nitrogenase ,Morphogenesis ,Anaerobiosis ,Molecular Biology ,Heterocyst ,chemistry.chemical_classification ,Anabaena ,Dinitrogenase Reductase ,biology.organism_classification ,Oxygen ,Heterocyst differentiation ,Mutagenesis, Insertional ,Enzyme ,Phenotype ,chemistry ,Biochemistry ,DNA Transposable Elements ,Bacteria ,Research Article - Abstract
Mutants of Anabaena sp. strain PCC 7120 that are incapable of sustained growth with air as the sole source of nitrogen were generated by using Tn5-derived transposons. Nitrogenase was expressed only in mutants that showed obvious morphological signs of heterocyst differentiation. Even under rigorously anaerobic conditions, nitrogenase was not synthesized in filaments that were unable to develop heterocysts. These results suggest that competence to synthesize nitrogenase requires a process that leads to an early stage of visible heterocyst development and are consistent with the idea that synthesis of nitrogenase is under developmental control (J. Elhai and C. P. Wolk, EMBO J. 9:3379-3388, 1990). We isolated mutants in which differentiation was arrested at an intermediate stage of heterocyst formation, suggesting that differentiation proceeds in stages; those mutants, as well as mutants with aberrant heterocyst envelopes and a mutant with defective respiration, expressed active nitrogenase under anaerobic conditions only. These results support the idea that the heterocyst envelope and heterocyst respiration are required for protection of nitrogenase from inactivation by oxygen. In the presence of air, such mutants contained less nitrogenase than under anaerobic conditions, and the Fe-protein was present in a posttranslationally modified inactive form. We conclude that internal partial oxygen pressure sufficient to inactivate nitrogenase is insufficient to repress synthesis of the enzyme completely. Among mutants with an apparently intact heterocyst envelope and normal respiration, three had virtually undetectable levels of dinitrogenase reductase under all conditions employed. However, three others expressed oxygen-sensitive nitrogenase activity, suggesting that respiration and barrier to diffusion of gases may not suffice for oxygen protection of nitrogenase in these mutants; two of these mutants reduced acetylene to ethylene and ethane.
- Published
- 1992
44. Use of a transposon with luciferase as a reporter to identify environmentally responsive genes in a cyanobacterium
- Author
-
Yuping Cai, C. P. Wolk, and Jean-Michel Panoff
- Subjects
Transposable element ,Genetics ,Reporter gene ,Multidisciplinary ,biology ,Anabaena ,biochemical phenomena, metabolism, and nutrition ,biology.organism_classification ,Genome ,Cell biology ,genomic DNA ,bacteria ,Luciferase ,Gene ,Heterocyst ,Research Article - Abstract
Anabaena, a filamentous cyanobacterium, is of developmental interest because, when deprived of fixed nitrogen, it shows patterned differentiation of N2-fixing cells called heterocysts. To help elucidate its early responses to a decrease in nitrogen, we used a derivative of transposon Tn5 to generate transcriptional fusions of promoterless bacterial luciferase genes, luxAB, to the Anabaena genome. Genes that responded to removal of fixed nitrogen or to other environmental shifts by increased or decreased transcription were identified by monitoring the luminescence of colonies from transposon-generated libraries. The Tn5 derivative transposed in Anabaena at ca. 1-4 x 10(-5) per cell and permitted high-resolution mapping of its position and orientation in the genome and facile cloning of contiguous genomic DNA.
- Published
- 1991
45. Cryopreservation of Microorganisms at Ultra-Low Temperatures. By Zdeněk Hubálek
- Author
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Jean-Michel Panoff
- Subjects
Chemistry ,Microorganism ,General Medicine ,Food science ,General Agricultural and Biological Sciences ,General Biochemistry, Genetics and Molecular Biology ,Cryopreservation - Published
- 1998
- Full Text
- View/download PDF
46. Response to cold shock: transcriptional and translational control?
- Author
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Jean-Michel Panoff and Isabelle Lucas
- Subjects
Chemistry ,Shock (circulatory) ,medicine ,medicine.symptom ,Microbiology ,Cell biology - Published
- 1996
- Full Text
- View/download PDF
47. Sulphated exopolysaccharides produced by two unicellular strains of cyanobacteria, Synechocystis PCC 6803 and 6714
- Author
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Françoise Joset, Jean-Michel Panoff, Henri Morvan, and Bernard Priem
- Subjects
Cyanobacteria ,chemistry.chemical_classification ,biology ,Synechocystis ,General Medicine ,Carbohydrate ,biology.organism_classification ,Polysaccharide ,Biochemistry ,Microbiology ,Algae ,chemistry ,Genetics ,Extracellular ,Molecular Biology ,Chemical composition ,Bacteria - Abstract
The exopolysaccharides (EPS) of two unicellular strains of cyanobacteria Synechocystis PCC 6803 and 6714, formed labile, radial structures, uniformly distributed on the cell surface, and stainable by specific dyes for acidic polysaccharides. The two strains produced EPS at similar rates, which depended, along with the duration of the producing phase, on the incubation conditions. The exopolysaccharides from both strains were constituted of at least 11–12 mono-oses, probably forming several types of polymers. They contained about 15–20% (w/w) uronic derivatives and 10–15% (w/w) osamines. Proteins represented 20–40% of total weight. A most interesting feature was the presence of 7–8% (molar ratio) sulphate residues, a characteristic that is otherwise limited to exopolysaccharides produced by eukaryotic algae.
- Published
- 1988
- Full Text
- View/download PDF
48. Selection by Anion-Exchange Chromatography of Exopolysaccharide Mutants of the Cyanobacterium Synechocystis Strain PCC 6803
- Author
-
Jean-Michel Panoff and Françoise Joset
- Subjects
chemistry.chemical_classification ,education.field_of_study ,Chromatography ,Ecology ,biology ,Strain (chemistry) ,Intrinsic viscosity ,Synechocystis ,Ion chromatography ,Population ,Genetics and Molecular Biology ,Uronic acid ,Apparent viscosity ,biology.organism_classification ,Polysaccharide ,Applied Microbiology and Biotechnology ,chemistry.chemical_compound ,chemistry ,Biochemistry ,education ,Food Science ,Biotechnology - Abstract
The degree of retention of whole cells of Synechocystis strain PCC 6803 on DEAE-cellulose columns was shown to depend on their content of exopolysaccharides, which are at least in part responsible for the external negative charge of the cells. This feature was used for the isolation of mutants modified in the apparent viscosity caused by these macromolecular constituents. When a wild-type suspension was loaded onto a DE52 column, the cells eluting in the two extreme fractions of a 0 to 5 M NaCl step gradient represented 10 −9 to 10 −7 of the total eluted population. The accuracy of the procedure was established through the analysis of four clones: Suc(0)32 and Suc(0)65 (0 M) and Suc(5)64A and Suc(5)61 (5 M). The decreased viscosity of the exopolymers of the two 0 M clones, which appeared identical, could be related to the production of molecules less charged in uronic acids and more readily liberated from the cells. The two 5 M clones exhibited a lower sedimentation velocity, correlating with either a 60% increase in uronic acid and a doubling of the specific viscosity of the exopolysaccharides [clone Suc(5)64A] or a doubling of the per-cell production of polymers otherwise identical to those from wild-type cells [clone Suc(5)61].
- Published
- 1989
49. Contribution transdisciplinaire à la réglementation de l'Union Européenne de l'expertise du risque biologique pour la santé et l'environnement
- Author
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Yebga Hot, Ange Hélène, Institut Demolombe, Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Normandie Université, Marie-Pierre Baudin-Maurin, and Jean-Michel Panoff
- Subjects
Adversarial proceedings ,Environmental law ,Droit de l’environnement ,[SHS.DROIT]Humanities and Social Sciences/Law ,Biological risk ,Expertise ,European Union ,Independence ,Transparency - Abstract
Biological risk expertise plays a central role in the development and implementation of health and environmental policy at EU level. Since the "mad cow" crisis, the Union's legislator has recognized the need to provide more guidance for this expertise. However, while EU law is concerned with the scientific framework of biological risk expertise, it does not address the issue of its legal framework in a comprehensive way. Indeed, while the requirements of independence, impartiality and transparency are affirmed with regard to the expert, their application lacks clarity and ultimately threatens the protection of the health and environment of EU citizens. To address this problem, this study proposes criteria for establishing EU-level regulation of biological risk expertise. These criteria were established after analysis of the existing legal framework, models of expertise from the legislation of certain Member States and third countries as well as doctrinal contributions.; L’expertise du risque biologique joue un rôle central dans l’élaboration et la mise en œuvre de la politique sanitaire et environnementale au niveau de l’Union européenne. Depuis la crise dite de la « vache folle », le législateur de l’Union a reconnu la nécessité d’encadrer davantage cette expertise. Toutefois, si le droit de l’Union s’intéresse au cadre scientifique de l’expertise du risque biologique, il traite de façon lacunaire la question de son cadre juridique. En effet, si les exigences d’indépendance, d’impartialité et de transparence sont affirmées à l’égard de l’expert, leur application manque de clarté et menace à terme la protection de la santé et de l’environnement des citoyens de l’Union. Pour remédier à ce problème, cette étude propose des critères ayant pour but l’établissement d’une réglementation au niveau de l’Union de l’expertise du risque biologique. Ces critères ont été établis après l’analyse du cadre juridique existant, des modèles d’expertise issus des législations de certains Etats membres et tiers à l’Union ainsi que de contributions doctrinales.
- Published
- 2019
50. Transdisciplinary contribution to the European Union's regulation of biological risk expertise for health and the environment
- Author
-
Yebga Hot, Ange Hélène, Institut Demolombe, Université de Caen Normandie (UNICAEN), Normandie Université (NU)-Normandie Université (NU), Normandie Université, Marie-Pierre Baudin-Maurin, and Jean-Michel Panoff
- Subjects
Adversarial proceedings ,Environmental law ,Droit de l’environnement ,[SHS.DROIT]Humanities and Social Sciences/Law ,Biological risk ,Expertise ,European Union ,Independence ,Transparency - Abstract
Biological risk expertise plays a central role in the development and implementation of health and environmental policy at EU level. Since the "mad cow" crisis, the Union's legislator has recognized the need to provide more guidance for this expertise. However, while EU law is concerned with the scientific framework of biological risk expertise, it does not address the issue of its legal framework in a comprehensive way. Indeed, while the requirements of independence, impartiality and transparency are affirmed with regard to the expert, their application lacks clarity and ultimately threatens the protection of the health and environment of EU citizens. To address this problem, this study proposes criteria for establishing EU-level regulation of biological risk expertise. These criteria were established after analysis of the existing legal framework, models of expertise from the legislation of certain Member States and third countries as well as doctrinal contributions.; L’expertise du risque biologique joue un rôle central dans l’élaboration et la mise en œuvre de la politique sanitaire et environnementale au niveau de l’Union européenne. Depuis la crise dite de la « vache folle », le législateur de l’Union a reconnu la nécessité d’encadrer davantage cette expertise. Toutefois, si le droit de l’Union s’intéresse au cadre scientifique de l’expertise du risque biologique, il traite de façon lacunaire la question de son cadre juridique. En effet, si les exigences d’indépendance, d’impartialité et de transparence sont affirmées à l’égard de l’expert, leur application manque de clarté et menace à terme la protection de la santé et de l’environnement des citoyens de l’Union. Pour remédier à ce problème, cette étude propose des critères ayant pour but l’établissement d’une réglementation au niveau de l’Union de l’expertise du risque biologique. Ces critères ont été établis après l’analyse du cadre juridique existant, des modèles d’expertise issus des législations de certains Etats membres et tiers à l’Union ainsi que de contributions doctrinales.
- Published
- 2019
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