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Aerobic anoxygenic phototrophic (AAP) bacteria are an important component of freshwater bacterioplankton. They can support their heterotrophic metabolism with energy from light, enhancing their growth efficiency. Based on results from cultures, it was hypothesized that photoheterotrophy provides an advantage under carbon limitation and facilitates access to recalcitrant or low-energy carbon sources. However, verification of these hypotheses for natural AAP communities has been lacking. Here, we conducted whole community manipulation experiments and compared the growth of AAP bacteria under carbon limited and with recalcitrant or low-energy carbon sources under dark and light (near-infrared light, λ > 800 nm) conditions to elucidate how they profit from photoheterotrophy. We found that AAP bacteria induce photoheterotrophic metabolism under carbon limitation, but they overcompete heterotrophic bacteria when carbon is available. This effect seems to be driven by physiological responses rather than changes at the community level. Interestingly, recalcitrant (lignin) or low-energy (acetate) carbon sources inhibited the growth of AAP bacteria, especially in light. This unexpected observation may have ecosystem-level consequences as lake browning continues. In general, our findings contribute to the understanding of the dynamics of AAP bacteria in pelagic environments., (© The Author(s) 2024. Published by Oxford University Press on behalf of FEMS.)

Aerobic spore-forming (ASF) bacteria have been reported to cause ropiness in bread. Sticky and stringy degradation, discoloration, and an odor reminiscent of rotting fruit are typical characteristics of ropy bread spoilage. In addition to economic losses, ropy bread spoilage may lead to health risks, as virulent strains of ASF bacteria are not uncommon. However, the lack of systematic approaches to quantify physicochemical spoilage characteristics makes it extremely difficult to assess rope formation in bread. To address this problem, the aim of this study was to identify, characterize and objectively assess the spoilage potential of ASF bacteria associated with ropy bread. Hence, a set of 82 ASF bacteria, including isolates from raw materials and bakery environments as well as strains from international culture collections, were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) and their species identity confirmed by 16S rRNA and gyrA or panC gene sequencing. A standardized approach supported by objective colorimetric measurements was developed to assess the rope-inducing potential (RIP) of a strain by inoculating autoclaved bread slices with bacterial spores. In addition, the presence of potential virulence factors such as swarming motility or hemolysis was investigated. This study adds B. velezensis, B. inaquosorum and B. spizizenii to the species potentially implicated of causing ropy bread spoilage. Most importantly, this study introduces a standardized classification protocol for assessing the RIP of a bacterial strain. Colorimetric measurements are used to objectively quantify the degree of breadcrumb discoloration. Furthermore, our results indicate that strains capable of inducing rope spoilage in bread often exhibit swarming motility and virulence factors such as hemolysis, raising important food quality considerations., Competing Interests: Declaration of competing interest None., (Copyright © 2024. Published by Elsevier B.V.)

Background: The porcine respiratory tract harbours multiple microorganisms, and the interactions between these organisms could be associated with animal health status. Pasteurella multocida is a culturable facultative anaerobic bacterium isolated from healthy and diseased porcine respiratory tracts. The interaction between P. multocida and other aerobic commensal bacteria in the porcine respiratory tract is not well understood. This study aimed to determine the interactions between porcine P. multocida capsular serotype A and D strains and other culturable aerobic bacteria isolated from porcine respiratory tracts using a coculture assay in conditioned media followed by calculation of the growth rates and interaction parameters., Results: One hundred and sixteen bacterial samples were isolated from five porcine respiratory tracts, and 93 isolates were identified and phylogenetically classified into fourteen genera based on 16S rRNA sequences. Thirteen isolates from Gram-negative bacterial genera and two isolates from the Gram-positive bacterial genus were selected for coculture with P. multocida. From 17 × 17 (289) interaction pairs, the majority of 220 pairs had negative interactions indicating competition for nutrients and space, while 17 pairs were identified as mild cooperative or positive interactions indicating their coexistence. All conditioned media, except those of Acinetobacter, could inhibit P. multocida growth. Conversely, the conditioned media of P. multocida also inhibited the growth of nine isolates plus themselves., Conclusion: Negative interaction was the major interactions among the coculture of these 15 representative isolates and the coculture with P. multocida. The conditioned media in this study might be further analysed to identify critical molecules and examined by the in vivo experiments. The study proposed the possibility of using these molecules in conditioned media to control P. multocida growth.

Phytoplankton is a key component of aquatic microbial communities, and metabolic coupling between phytoplankton and bacteria determines the fate of dissolved organic carbon (DOC). Yet, the impact of primary production on bacterial activity and community composition remains largely unknown, as, for example, in the case of aerobic anoxygenic phototrophic (AAP) bacteria that utilize both phytoplankton-derived DOC and light as energy sources. Here, we studied how reduction of primary production in a natural freshwater community affects the bacterial community composition and its activity, focusing primarily on AAP bacteria. The bacterial respiration rate was the lowest when photosynthesis was reduced by direct inhibition of photosystem II and the highest in ambient light condition with no photosynthesis inhibition, suggesting that it was limited by carbon availability. However, bacterial assimilation rates of leucine and glucose were unaffected, indicating that increased bacterial growth efficiency (e.g., due to photoheterotrophy) can help to maintain overall bacterial production when low primary production limits DOC availability. Bacterial community composition was tightly linked to light intensity, mainly due to the increased relative abundance of light-dependent AAP bacteria. This notion shows that changes in bacterial community composition are not necessarily reflected by changes in bacterial production or growth and vice versa. Moreover, we demonstrated for the first time that light can directly affect bacterial community composition, a topic which has been neglected in studies of phytoplankton-bacteria interactions. IMPORTANCE Metabolic coupling between phytoplankton and bacteria determines the fate of dissolved organic carbon in aquatic environments, and yet how changes in the rate of primary production affect the bacterial activity and community composition remains understudied. Here, we experimentally limited the rate of primary production either by lowering light intensity or by adding a photosynthesis inhibitor. The induced decrease had a greater influence on bacterial respiration than on bacterial production and growth rate, especially at an optimal light intensity. This suggests that changes in primary production drive bacterial activity, but the effect on carbon flow may be mitigated by increased bacterial growth efficiencies, especially of light-dependent AAP bacteria. Bacterial activities were independent of changes in bacterial community composition, which were driven by light availability and AAP bacteria. This direct effect of light on composition of bacterial communities has not been documented previously., (Copyright © 2020 Piwosz et al.)

Beef is an animal food sensitive to deterioration due to its rich nutrient content. Therefore, some preservation techniques are applied. These include vacuum packaging, a modified atmosphere, a controlled atmosphere and an edible film coating. In this study, it was aimed to extend the shelf life of beef using vacuum packaging (VP) and chitosan coating with vacuum packaging (CC + VP). For this purpose, total mesophilic aerobic bacteria (TMAB), Stapylococcus aureus, lactic acid bacteria (LAB) counts, thiobarbituric acid (TBA) values and total volatile basic nitrogen (TVB-N) content were analyzed in beef obtained from local markets. As a result, it was found that the chitosan coating reduced the TMAB, LAB and TVB-N values and inhibited all S. aureus up to day 15 of storage. In addition, it was seen that the application of CC + VP was significantly more effective (p˂0.05) on the reduction of the TBA value, compared to the VP application over a long period of storage (45 days). The combined use of the two technologies is more effective on TVB-N. According to the data obtained from this study, because of the antimicrobial and antioxidant properties of chitosan, it has been concluded that it can be used as a bio-preservative in the meat industry., Competing Interests: Declaration of Competing interest The authors declare no conflict of interest., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Saline wastewaters are usually generated by various industries, including the chemical, pharmaceutical, agricultural, and aquacultural industries. The discharge of untreated high-salinity wastewater may cause serious environmental pollution and damage the aquatic, terrestrial, and wetland ecosystems. For many countries, the treatment of saline wastewater has become an important task. Generally, saline wastewaters are treated through physical and chemical methods. However, these traditional techniques are associated with higher treatment costs and the generation of byproducts. In contrast, biotreatment techniques are environmentally friendly and inexpensive. This review highlights the sources and environmental concerns of high-salinity wastewater and illustrates the latest problems and solutions to the use of biological approaches for treating saline wastewater. Although high salinity may inhibit the effectiveness of aerobic and anaerobic biological wastewater treatment methods, such strategies as selecting salt-adapted microorganisms capable of degrading pollutants with tolerance to high salinity and optimizing operating conditions can be effective. This mini-review may serve as a reference for future efforts to treat high-salinity wastewater.

Soaking hay fodder to reduce dust and soluble carbohydrate (WSC) contents prior to feeding is common practice among horse owners. Soaking can increase bacteria load in hay but no information exists on how this process alters the bacteria profile, which could pose a health risk or digestive challenge, to horses by introducing foreign bacteria into the gastrointestinal tract and so altering the normal profile. The current objectives were to map the bacterial profile of 3 different hays and determine how soaking alters this with the aim of improving best practice when feeding stabled horses. A Perennial Rye grass hay and two meadow s hays were soaked for 0, 1.5, 9 or 16 hours. Pre and post treatment, hays were analysed for WSC and total aerobic bacteria (CFU/g), and differences in bacteria family profiles were determined using ANOVA with significance set at P<0.05. Bacteria were identified via genomic DNA extraction and 16S library preparation (V3 and V4 variable region of 16S rRNA) according to the Illumina protocol. Differences in family operational taxonomic units (OTUs) between individual dry hays and different soaking times were identified via paired t-tests on the DESeq2 normalised data and false discovery rates accounted for using Padj (P<0.05). Mean % WSC losses and actual g/kg lost on DM basis (+/- SE) increased with soaking time being 18% = 30 (10.7), 38% = 72 (43.7), and 42% = 80 (38.8) for 1.5, 9 and 16 hours soak respectively. No relationship existed between WSC leaching and bacteria growth or profile. Grass type influenced bacterial profiles and their responses to soaking, but no differences were seen in richness or Shannon diversity indices. PCA analyses showed clustering of bacteria between meadow hays which differed from the perennial rye grass hay and this difference increased post soaking. Soaking hay pre-feeding causes inconsistent WSC leaching, bacteria growth and alterations in bacterial profiles which are unpredictable but may decrease the hygienic quality of the fodder., Competing Interests: The commercial affiliation with Mars Horsecare for this study does not alter our adherence to PLOS ONE policies on sharing data and materials.

Geobacter sulfurreducens was originally considered a strict anaerobe. However, this bacterium was later shown to not only tolerate exposure to oxygen but also to use it as terminal electron acceptor. Research performed has so far only revealed the general ability of G. sulfurreducens to reduce oxygen, but the oxygen uptake rate has not been quantified yet, nor has evidence been provided as to how the bacterium achieves oxygen reduction. Therefore, microaerobic growth of G. sulfurreducens was investigated here with better defined operating conditions as previously performed and a transcriptome analysis was performed to elucidate possible metabolic mechanisms important for oxygen reduction in G. sulfurreducens. The investigations revealed that cell growth with oxygen is possible to the same extent as with fumarate if the maximum specific oxygen uptake rate (sOUR) of 95 mgO2 gCDW-1 h-1 is not surpassed. Hereby, the entire amount of introduced oxygen is reduced. When oxygen concentrations are too high, cell growth is completely inhibited and there is no partial oxygen consumption. Transcriptome analysis suggests a menaquinol oxidase to be the enzyme responsible for oxygen reduction. Transcriptome analysis has further revealed three different survival strategies, depending on the oxygen concentration present. When prompted with small amounts of oxygen, G. sulfurreducens will try to escape the microaerobic area; if oxygen concentrations are higher, cells will focus on rapid and complete oxygen reduction coupled to cell growth; and ultimately cells will form protective layers if a complete reduction becomes impossible. The results presented here have important implications for understanding how G. sulfurreducens survives exposure to oxygen., Competing Interests: The authors have declared that no competing interests exist.

Microbially induced CaCO 3 precipitation (MICP) can give concrete self-healing properties. MICP agents are typically bacterial endospores which are coated into shelled granules, infused into expanded clay, or embedded into superabsorbent polymer (SAP). When small cracks appear in the cured concrete, the encapsulation is broken and the metabolic CO 2 production from the germinated bacteria causes healing of the cracks by precipitation of CaCO 3 . Such systems are being tested empirically at large scales, but survival of endospores through preparation and application, as well as germination and growth kinetics of the germinated vegetative cells, remains poorly resolved. We encapsulated endospores of Bacillus subtilis and Bacillus alkalinitrilicus in crosslinked acrylamide-based SAP and quantified their germination, growth, and, in the case of B. alkalinitrilicus, CaCO 3 precipitation potential. The endospores survived crosslinking and desiccation inside the polymer matrix. Microcalorimetry and microscopy showed that ~ 80% of the encapsulated endospores of both strains readily germinated after rehydration of freeze-dried SAP. Germinated cells grew into dense colonies of cells inside the SAP, and those of B. alkalinitrilicus calcified with up to 0.3 g CaCO 3 produced per g desiccated SAP when incubated aerobically. Measurements by planar optodes indicated that the precipitation rates were inherently oxygen limited due to diffusional constraints, rather than limited by electron donor or Ca 2+ availability. Such oxygen limitation will limit MICP in all water-saturated and oxygen-dependent systems, and MICP agents based on anaerobic bacteria, e.g., nitrate reducers, should be developed to broaden the applicability of bioactive self-healing concretes to wet and waterlogged environments.

Background: Human skin is an appropriate environment for the growth of different types of microbes that may inhabit the skin as commensal flora. This study aims at identifying the diversity of skin microbiota in healthy Saudi population. In this study, 80 Saudi subjects of both males and females, from different habitat, and different ages (elderly and young), were recruited to determine the aerobic bacterial flora from their three skin sites; hand, scalp and foot. A single colony obtained from aerobic culture was identified using Biomérieux VITEK® 2 system. For those not being identified by VITEK® 2 system, the identification was conducted using 16 s rRNA sequence., Results: Thirty-three bacterial species were isolated from males, whilst 24 species were isolated from females. Micrococci are the predominant organisms, followed by Staphylococci, Pantoea species, and lastly Enterococcus faecium. Acinetobacter baumannii, Enterococcus faecalis, and Klebsiella pneumoniae were only found in elder subjects, while Pseudomonas aeruginosa was isolated from the young only. The number of bacterial isolates in the elders was higher that of the young. The average number of flora was larger in foot, then hand and lastly scalp., Conclusion: Here we show the difference in the number of cultivable bacteria across age and gender that may result in the variety of local skin infection. This study paves the way to further investigation in the aspect of in-depth metagenomics analysis and host-pathogen interaction.

Cold plasma technology offers new opportunities to the decontamination and preservation of fruits and vegetables. In the present research, strawberries were cut into four wedges and then treated with dielectric barrier discharge plasma at 45 kV for 1 min and stored for 1 week (4 °C). Metabolomic analysis suggested that plasma treatment improved the biosynthesis of the metabolites in the "flavones and flavonol biosynthesis" pathway and "biosynthesis of phenylpropanoids" pathway in fresh-cut strawberries. Physiological assay demonstrated that plasma treatment maintained the texture properties and inhibited microbial growth of fresh-cut strawberries. In addition, plasma treatment also promoted the accumulation of total phenolics, total flavonoid, and anthocyanin by enhancing the critical enzyme activities and activating related gene expression in phenylpropanoid as well as reactive oxygen species metabolism, which contributed greatly to the enhancement of antioxidant capacity of strawberry wedges. Our investigation provided a new perspective of the effect of plasma treatment on the safety and quality of strawberry wedges and suggested that cold plasma treatment holds promise as an emerging processing technology for improving the quality and antioxidant activity of postharvest fruits and vegetables.

The effect of superchilled storage (SC, -4 °C) on shelf life and quality characteristics of M. longissimus lumborum from Chinese Yellow cattle compared with traditional chilling (TC, 2 °C) and frozen storage (-18 °C) was studied. The shelf life of beef steaks held at -4 °C extended to 12 weeks based on the total volatile basic nitrogen (TVB-N) value, which was 2.4 times longer than steaks stored at 2 °C. As the storage time increased, SC samples showed a lower increase of the total aerobic count (TAC), pH and thiobarbituric acid reactive substances (TBARS) values compared to TC samples. Further, L ⁎ and a ⁎ values of SC samples changed more slowly than that of TC samples. Beef steaks held frozen had a longer shelf life than SC steaks, however, the shear force of frozen steaks remained above 55 N throughout the storage time indicative of toughness. Consequently, SC offers an effective approach for maintaining better shelf life and quality of beef steaks., (Copyright © 2018. Published by Elsevier Ltd.)

The objective of this work was to determine the effects of infrared radiation combined with heating on grape seeds and oil quality. Experimental results showed that high moisture removal was achieved through infrared radiation heating. After infrared radiation heating for 108 s, the inactivation rates of total aerobic bacterial and total mold-yeast counts of the grape seeds were 1.97 ± 0.12 and 0.62 ± 0.09 log CFU/g, respectively. The maximum microbial reduction was achieved after infrared radiation heating of the grape seeds to 135 ℃ and subsequent holding at 75 ℃ for 60 min. The crude oil yield of samples subjected to these conditions was 10.39%, which was significantly higher ( p < 0.05) than that of the control sample, and their final moisture content was 7.20%. Additionally, increases in the free fatty acid content and peroxide value of the oil were achieved. The iodine value of the oil decreased. In conclusion, surface pasteurization with a high oil yield could be achieved by the combination of infrared radiation heating and the holding process. Consequently, infrared radiation treatment is suggested to be a promising method for the surface pasteurization of grape seeds.

The effect of pH and the spoilage of black wildebeest Longissimus thoracis et lumborum (LTL) muscles with normal (pH > 6.06) and high pH (DFD; pH < 6.06) was investigated for 12 days under refrigerated (5 ± 1 °C) aerobic conditions. Results showed that pH affected colour, as initial values from Normal samples (L* = 33.08, a* = 13.60, b* = 10.29, C* = 17.10 and H ab  = 36.85) were greater than values for DFD meat (L* = 27.21, a* = 11.10, b* = 6.97, C* = 13.12 and H ab  = 32.08). Initial bacterial counts from DFD and Normal pH samples did not differ significantly. Over time, pH decreased for Normal and DFD samples until the 6th and 9th day, respectively, whilst both samples showed a significant decrease in redness and colour intensity. Aerobic bacteria and Enterobacteriaceae reached 7 log cfu/g > 4 days earlier than Normal pH samples and bacterial growth rate was >1.09-fold faster in DFD than Normal meat., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Wastewater treatment by means of algal-bacterial granules has become a hot topic worldwide recently. Rapid granulation of algal-bacterial granules was achieved in an aerobic bacterial granular sequencing batch reactor (SBR) under natural sunlight exposure. Occurrence of abundant filamentous bacteria bridging the water-born algae, and overproduction of extracellular polymeric substances (EPS) (especially polysaccharides (PS), tryptophan & protein-like, and humic acid-like substances) were observed on the first 3 days, while the algae grew into the inner side of the granules and mature granules were obtained on day 7. The growth of the water-born algae slightly decreased the settleability, mean sizes of the granules, but stimulated the bioactivity significantly. Whereas, the biomass retention decreased before day 3, and got stable soon with the maturation period with symbiotic growth of algal-bacterial biomass. Illumina results revealed that the introduction of algae reduced the richness and diversity of bacterial community. Besides, few changes in structure and some compositions shifts in bacterial communities were found, while the predominant algae shifted from Diatomea to green algae Chlorophyceae. The possible mechanism for natural sunlight induced granulation of algal-bacterial granules was thus proposed based on the interactions between algae and bacteria., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Microalgae-based treatment systems have been successfully used for the polishing of domestic wastewater. Research is underway in studying the suitability of using these systems as main treatment units. This study focuses on comparing the performances of a mixed microalgal culture and an aerobic bacterial culture, based on the kinetic evaluation, in removing organic carbon from a kitchen wastewater. The two systems were operated at six different solid retention times (SRTs)-2, 4, 6, 8, 10, and 12 days in continuous mode. The influent and effluent samples were analyzed for chemical oxygen demand (COD), total organic carbon (TOC), total nitrogen (TN), phosphates, and surfactants. Steady-state kinetics (k, K s , Y, and k d ) for organic carbon removal were obtained by fitting experimental data in linearized Michaelis-Menten and Monod equations. The mixed microalgal system showed similar or better performance in COD and TN removal (88 and 85%, respectively) when compared with the COD and TN removal by the aerobic bacterial system (89 and 48%). A maximum lipid yield of 40% (w/w of dry biomass) was observed in the microalgal system. Saturated fatty acids accounted for 50% of the total observed FAME species. The study indicates that the mixed microalgal culture is capable of treating kitchen wastewater and has the potential to replace aerobic bacteria in biological treatment systems in certain cases.

The increase of extreme drought and precipitation events due to climate change will alter microbial processes. Perturbation experiments demonstrated that microbes are sensitive to environmental alterations. However, only little is known on the legacy effects in microbial systems. Here, we designed a laboratory microcosm experiment using aerobic methane-consuming communities as a model system to test basic principles of microbial resilience and the role of changes in biomass and the presence of non-methanotrophic microbes in this process. We focused on enrichments from soil, sediment, and water reflecting communities with different legacy with respect to exposure to drought. Recovery rates, a recently proposed early warning indicator of a critical transition, were utilized as a measure to detect resilience loss of methane consumption during a series of dry/wet cycle perturbations. We observed a slowed recovery of enrichments originating from water samples, which suggests that the community's legacy with a perturbation is a contributing factor for the resilience of microbial functioning.

To avoid the loss of carotenoids and increasing the tannin content associated with pasteurization, we tested ultra-high pressure treatment of ripe persimmon beverage. We compared microbial counts (aerobic bacteria, coliforms, and mould), carotenoid contents, and water-soluble tannin contents between heat- and ultra-high pressure-treated beverages. No microbial contamination was detected after pasteurization or ultra-high pressure treatment at 400 MPa for more than 5 min. Ultra-high pressure treatment significantly prevented the reduction in carotenoids (lutein, zeaxanthin, β-cryptoxanthin, β-carotene, lycopene), with losses of 3.9-28.7%, as compared to the 65% loss after pasteurization. Moreover, ultra-high pressure did not induce an increase in water-soluble tannin, which causes astringent taste, whereas water-soluble tannins were increased three times by heat treatment. In conclusion, ultra-high pressure showed the same microbial control effect as pasteurization, while it did not cause carotenoid degeneration and increased tannin and thus, it better maintained the quality of ripe persimmon beverage.

The objective of the current study was to determine the effects of deboning time, three steps of sausage processing (grinding, salting, and batter formulation), and storage time (of raw materials and cooked sausage) on the growth (log CFU/g) of aerobic bacteria, lactic acid bacteria, and inoculated Salmonella and E. coli. Beef deboning time did not influence bacterial counts (P≥0.138). However, salting of raw ground beef resulted in a 0.4-log reduction in both aerobic plate count (APC) and Salmonella (P≤0.001). Lactic acid bacteria were increased from non-detectable concentration (0.54 log) on d 0 to 3.8 log on d 120 of vacuum storage (P≤0.019). Salmonella counts were increased (P<0.001) over storage time (3.2 to 3.3 log CFU/g from d 0 to 10). Results indicated that salting and batter formulation had a greater impact on bacterial counts than rigor state of raw beef., (Published by Elsevier Ltd.)

Remediation of polluted groundwater often requires oxygen delivery into subsurface to sustain aerobic bacteria. Air sparging or injection of oxygen containing solutions (e.g., hydrogen peroxide) into the subsurface are common. In this study visible light was delivered into the subsurface using radially emitting optical fibers. Phototrophic organisms grew near the optical fiber in a saturated sand column. When applying light in on-off cycles, dissolved oxygen (DO) varied from super saturation levels of >15 mg DO/L in presence of light to under-saturation (<5 mg DO/L) in absence of light. Non-photosynthetic bacteria dominated at longer radial distances from the fiber, presumably supported by soluble microbial products produced by the photosynthetic microorganisms. The dissolved oxygen variations alter redox condition changes in response to light demonstrate the potential to biologically deliver oxygen into the subsurface and support a diverse microbial community. The ability to deliver oxygen and modulate redox conditions on diurnal cycles using solar light may provide a sustainable, long term strategy for increasing dissolved oxygen levels in subsurface environments and maintaining diverse biological communities., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

As important pests, scarab beetle larvae survive on plant biomass and the microbiota of the fermentation chamber play an important role in the digestion of lignocellulose-rich diets. However, the cultivable microbes, especially the anaerobic cultivable microbes, are still largely unknown. Here, both cultivable anaerobic and aerobic bacterial communities associated with the fermentation chamber of Holotrichia parallela larvae were investigated. In total bacteria cells directly enumerated by the 4', 6-diamidino-2-phenylindole (DAPI) staining method, the viable plate counts of cultivable bacteria in the fermentation chamber accounted for 0.92% of proportion. These cultivable bacteria were prone to attach to the fermentation chamber wall (88.41%) compared to the chamber contents. Anaerobic bacteria were dominant in the cultivable bacteria attaching to the fermentation chamber wall (70.20%), while the quantities of anaerobes and aerobes were similar in the chamber contents. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), fingerprinting and sequence analysis of isolated colonies revealed that the cultivable bacteria are affiliated with class γ-Proteobacteria, Bacteroidia, Actinobacteria, Clostridia and β-Proteobacteria. γ-Proteobacteria was the major type of anaerobic cultivable bacteria and even the only one type of aerobic cultivable bacteria. Taken together, our results suggest, for the first time, that anaerobic microbiota are dominant in cultivable bacteria in the special anoxia niche of the fermentation chamber from H. parallela larvae. These bacterial isolates could be a treasure trove for screening lignocellulytic microbes which are essential for the plant biomass digestion of this scarab species.

Tetrachloroethylene (PCE) is among the most ubiquitous chlorinated compounds found in groundwater contamination. Its chlorinated degradation by-products remain highly toxic. In this study, an anaerobic/aerobic permeable reactive barrier system consisting of four different functional layers was designed to remediate PCE-contaminated groundwater. The first (oxygen capture) layer maintained the dissolved oxygen (DO) concentration at < 1.35 mg/L in influent supplied to the second (anaerobic) layer. The third (oxygen-releasing) layer maintained DO concentration at > 11.3 mg/L within influent supplied to the fourth (aerobic) layer. The results show that 99% of PCE was removed, mostly within the second layer (anaerobic). Furthermore, the toxic by-products trichloroethylene (TCE), dichloroethylene (DCE), and vinyl chloride (VC) were further degraded by 98, 90, and 92%, respectively, in layer 4 (aerobic). Thus, the designed anaerobic/aerobic permeable reactive barrier system could control both PCE and its degradation by-products, showing great potential as an efficient remediation alternative for the in situ treatment of PCE-contaminated groundwater.

Aim: Although it is known that bacterial mechanisms are involved in dental calculus formation, which is a predisposing factor in periodontal diseases, there have been few studies of such associations, and therefore, information available is limited. The purpose of this study was to isolate and identify aerobic bacteria responsible for direct calcification from supragingival calculus samples., Materials and Methods: The study was conducted using supragingival calculus samples from patients with periodontal disease, which was required as part of conventional treatment. Isolations were performed by sampling the supragingival calculus with buffer and inoculating the samples on media on which crystallization could be observed. The 16S recombinant DNA of the obtained pure cultures was then amplified and sequenced., Results: A few bacterial species that have not previously been associated with mineralization or identified on bacterial plaque or calculus were detected. The bacteria that caused mineralization an aerobic environment are identified as Neisseria flava, Aggregatibacter segnis, Streptococcus tigurinus, and Morococcus cerebrosus., Conclusion: These findings proved that bacteria potentially play a role in the etiopathology of supragingival calculus. The association between the effects of the identified bacteria on periodontal diseases and calculus formation requires further studies.

Aerobic anoxygenic phototrophic (AAP) bacteria are microorganisms that can harvest light energy using bacteriochlorophyll a to supplement their predominantly organotrophic metabolism. Growth enhancement by light has repeatedly been demonstrated in laboratory experiments with AAP isolates. However, the ecological advantage of light utilization is unclear, as it has never been proven in the natural environment. Here, we conducted manipulation experiments in the NW Mediterranean and found that AAP bacteria display high growth rates which are controlled to a large extent by intense grazing pressure and phosphorous availability. Foremost, we found that, contrarily to the bulk bacterioplakton, AAP bacteria display higher growth rates when incubated under light-dark cycles than in complete darkness. These results represent the first direct evidence that natural populations of marine AAP bacteria can be stimulated by light.

In this study, we demonstrated that anaerobic granular sludge could be successfully transformed into aerobic granular sludge in a continuous up-flow reactor in 45 days. An aerobic microbial community successfully developed in the granules and high organic matter and nitrogen removal performance was achieved. Under an ammonia nitrogen loading rate of 0.8 kg N/(m 3 day), ammonia nitrogen and the total nitrogen removal efficiency of the reactor reached up to 100 and 93%, respectively. An obvious bacterial community shift in granular sludge was observed during the transformation process. By comparing with the bacterial community in aerobic granules cultivated from floccular activated sludge, some bacteria (affiliated with Comamonadaceae, Xanthomonadaceae, Rhodocyclaceae, Moraxellaceae, and Nitrosomonadaceae) playing significant roles in maintaining the structures and functions of aerobic granules were identified. After the transformation, the granules could be clearly separated into the inner core and outer shell. 16S rRNA gene sequencing results indicated many bacterial species present in both the inner core and outer shell; however, their abundance differed significantly. Overall, this study confirms the feasibility of transforming anaerobic granules into aerobic granules and provides novel approaches and insights to understand the microbial ecology in granular sludge.

The human vagina constitutes a complex ecosystem created through relationships established between host mucosa and bacterial communities. In this ecosystem, classically defined bacterial aerobes and anaerobes thrive as communities in the microaerophilic environment. Levels of CO 2 and O 2 present in the vaginal lumen are impacted by both the ecosystem's physiology and the behavior and health of the human host. Study of such complex relationships requires controlled and reproducible causational approaches that are not possible in the human host that, until recently, was the only place these bacterial communities thrived. To address this need we have utilized our ex vivo human vaginal mucosa culture system to support controlled, reproducible colonization by vaginal bacterial communities (VBC) collected from healthy, asymptomatic donors. Parallel vaginal epithelial cells (VEC)-VBC co-cultures were exposed to two different atmospheric conditions to study the impact of CO 2 concentrations upon the anaerobic bacteria associated with dysbiosis and inflammation. Our data suggest that in the context of transplanted VBC, increased CO 2 favored specific lactobacilli species defined as microaerophiles when grown as monocultures. In preliminary studies, the observed community changes also led to shifts in host VEC phenotypes with significant changes in the host transcriptome, including altered expression of select molecular transporter genes. These findings support the need for additional study of the environmental changes associated with behavior and health upon the symbiotic and adversarial relationships that are formed in microbial communities present in the human vaginal ecosystem., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Malnutrition is the leading cause of death worldwide in children under the age of five, and is the focus of the first World Health Organization (WHO) Millennium Development Goal. Breastfeeding, food and water security are major protective factors against malnutrition and critical factors in the maturation of healthy gut microbiota, characterized by a transient bifidobacterial bloom before a global rise in anaerobes. Early depletion in gut Bifidobacterium longum, a typical maternal probiotic, known to inhibit pathogens, represents the first step in gut microbiota alteration associated with severe acute malnutrition (SAM). Later, the absence of the Healthy Mature Anaerobic Gut Microbiota (HMAGM) leads to deficient energy harvest, vitamin biosynthesis and immune protection, and is associated with diarrhea, malabsorption and systemic invasion by microbial pathogens. A therapeutic diet and infection treatment may be unable to restore bifidobacteria and HMAGM. Besides refeeding and antibiotics, future trials including non-toxic missing microbes and nutrients necessary to restore bifidobacteria and HMAGM, including prebiotics and antioxidants, are warranted in children with severe or refractory disease., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Selenium (Se) nanoparticles are often synthesized by anaerobes. However, anaerobic bacteria cannot be directly applied for bioremediation of contaminated top soil which is generally aerobic. In this study, a selenite-reducing bacterium, Citrobacter freundii Y9, demonstrated high selenite reducing power and produced elemental nano-selenium nanoparticles (nano-Se 0 ) under both aerobic and anaerobic conditions. The biogenic nano-Se 0 converted 45.8-57.1% and 39.1-48.6% of elemental mercury (Hg 0 ) in the contaminated soil to insoluble mercuric selenide (HgSe) under anaerobic and aerobic conditions, respectively. Addition of sodium dodecyl sulfonate enhanced Hg 0 remediation, probably owing to the release of intracellular nano-Se 0 from the bacterial cells for Hg fixation. The reaction product after remediation was identified as non-reactive HgSe that was formed by amalgamation of nano-Se 0 and Hg 0 . Biosynthesis of nano-Se 0 both aerobically and anaerobically therefore provides a versatile and cost-effective remediation approach for Hg 0 -contaminated surface and subsurface soils, where the redox potential often changes dramatically., (Copyright © 2016. Published by Elsevier Ltd.)

Biodegradation of a monoazo dye - Acid Orange 7 (AO7) was investigated by using an internal circulation baffled biofilm reactor. For accelerating AO7 biodegradation, endogenous electron donors produced from AO7 by UV photolysis were added into the reactor. The result shows that AO7 removal rate can be accelerated by using its endogenous electron donors, such as sulfanilic and aniline. When initial AO7 concentration was 13.6mg/L, electron donors generated by 8h UV photolysis were added into the same system. The biodegradation rate 0.4mg 0.05 h -1 was enhanced 60% than that without adding electron donor. Furthermore, sulfanilic and aniline were found to be the main endogenous electron carriers, which could accelerate the steps of the azo dye biodegradation., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Menaquinone (MK) biosynthesis pathway is a potential target for evaluating antimicrobials in gram-positive bacteria. Here, 1,4-dihydroxy-2-naphthoate prenyltransferase (MenA) was targeted to reduce methicillin-resistant Staphylococcus aureus (MRSA) growth. MenA inhibiting, long chain-based compounds were designed, synthesized and evaluated against MRSA and menaquinone utilizing bacteria in aerobic conditions. The results showed that these bacteria were susceptible to most of the compounds. Menaquinone (MK-4) supplementation rescued MRSA growth, suggesting these compounds inhibit MK biosynthesis. 3a and 7c exhibited promising inhibitory activities with MICs ranging 1-8 μg/mL against MRSA strains. The compounds did not facilitate small colony variant formation. These compounds also inhibited the biofilm growth by MRSA at high concentration. Compounds 3a, 6b and 7c displayed a promising extracellular bactericidal activity against MRSA at concentrations equal to and four-fold less than their respective MICs. We also observed cytokines released from THP-1 macrophages treated with compounds 3a, 6b and 7c and found decreases in TNF-α and IL-6 release and increase in IL-1β. These data provide evidence that MenA inhibitors act as TNF-α and IL-6 inhibitors, raising the potential for development and application of these compounds as potential immunomodulatory agents.

Rapid and early identification of micro-organisms in blood has a key role in the diagnosis of a febrile patient, in particular, in guiding the clinician to define the correct antibiotic therapy. This study presents a simple and very fast method with high performances for identifying bacteria by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) after only 4 h of incubation. We used early bacterial growth on PolyViteX chocolate agar plates inoculated with five drops of blood-broth medium deposited in the same point and spread with a sterile loop, followed by a direct transfer procedure on MALDI-TOF MS target slides without additional modification. Ninety-nine percentage of aerobic bacteria were correctly identified from 600 monomicrobial-positive blood cultures. This procedure allowed obtaining the correct identification of fastidious pathogens, such as Streptococcus pneumoniae, Neisseria meningitidis and Haemophilus influenzae that need complex nutritional and environmental requirements in order to grow. Compared to the traditional pathogen identification from blood cultures that takes over 24 h, the reliability of results, rapid performance and suitability of this protocol allowed a more rapid administration of optimal antimicrobial treatment in the patients., Significance and Impact of the Study: Bloodstream infections are serious conditions with a high mortality and morbidity rate. Rapid identification of pathogens and appropriate antimicrobial therapy have a key role for successful patient outcome. In this work, we developed a rapid, simplified, accurate, and efficient method, reaching 99 % identification of aerobic bacteria from monomicrobial-positive blood cultures by using early growth on enriched medium, direct transfer to target plate without additional procedures, matrix-assisted laser desorption ionization-time of flight mass spectrometry and SARAMIS database. The application of this protocol allows to anticipate appropriate antibiotic therapy., (© 2016 The Society for Applied Microbiology.)

This study evaluates hygiene practices on 53 dairy farms in the Jijel and Blida regions of Algeria. A survey questionnaire was drawn up covering milking conditions and cleaning of the equipment. In parallel, bacteriological analyses were carried out to estimate the rate, source and development of bacterial contamination in raw milk produced on the farm. In addition, screening was performed to detect the presence of inhibitor residues. The results of the survey revealed poor livestock conditions and milking practices that could explain the presence of bacteria in cow's milk. The bacteriological results showed that 76.1% of milk samples taken from cow udders complied with legal standards, compared with only 35.8% of milk samples taken from storage tanks. Moreover, bacterial inhibitors were detected in 28.8% of milk samples. These results showed that the hands of milkers, udders, teat cups, utensils, the water used during milking and the milking environment were all potential sources of milk contamination by the bacteria under investigation. These results suggest that, to improve the bacteriological quality of milk, there is a need to introduce a quality policy which places a premium on milk of high bacteriological quality and aims to generalise good hygiene practices throughout the dairy production chain., (© OIE (World Organisation for Animal Health), 2016.)

Aerobic Anoxygenic Phototrophic (AAP) bacteria are bacteriochlorophyll (BChl) a -containing organisms which use light energy to supplement their predominantly heterotrophic metabolism. Here, we investigated mortality and growth rates of AAP bacteria in three different freshwater lakes in Central Europe: the mountain lake Plešné, the oligo-mesotrophic Lake Stechlin and the forest pond Huntov. The mortality of AAP bacteria was estimated from diel changes of BChl a fluorescence. Net and gross growth rates were calculated from the increases in AAP cell numbers. The gross growth rates of AAP bacteria ranged from 0.38 to 5.6 d -1 , with the highest values observed during summer months. Simultaneously, the rapidly growing AAP cells have to cope with an intense grazing pressure by both zooplankton and protists. The presented results document that during the day, gross growth usually surpased mortality. Our results indicate that AAP bacteria utilize light energy under natural conditions to maintain rapid growth rates, which are balanced by a generally intense grazing pressure., (© 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.)

The objective of this study was to identify the maximum time of refrigerated storage before aerobic psychrotrophic bacteria grew to a level indicative of spoilage (7 log cfu/g) or other indicators of spoilage were observed for whole-muscle pork and ground pork sausage packaged using FreshCase technology. Pork chops and pork sausage were packaged using conventional vacuum packaging without nitrite in film (Control) or using FreshCase technology and were compared with respect to microbial counts, pH, instrumental color measurements, lipid oxidation level, and sensory properties. The storage life was 45 d for pork chops stored in FreshCase packages at 1°C and 19 d for ground pork sausage stored under the same condition. Results indicated that both pork chops and sausage stored in FreshCase packages retained redder color ( < 0.05) than those stored in Control packages. No differences ( > 0.05) existed between Control and FreshCase packaged samples for any off-odor detection for either pork chops or sausage. Moreover, levels of oxidative rancidity in all packages had low thiobarbituric acid reactive substances values. The results indicated that FreshCase technology can be used to extend storage life of pork products without having adverse effects on pork quality.

The objective of this study was to identify the maximum time of refrigerated storage before aerobic psychrotrophic bacteria (APB) grew to a level indicative of spoilage (7 log cfu/g) or other indicators of spoilage were observed for whole muscle beef and ground beef packaged using FreshCase technology. Storage life for beef steaks stored in FreshCase packages at 4°C was 36 d, with ground beef stored in FreshCase packages at 4°C lasting 10 d. Additionally, greater ( < 0.05) a* (redness) values were detected in FreshCase packaged samples of both beef steaks and ground beef over storage time. At the point of spoilage, off-odors were detected at very low levels in all samples along with low thiobarbituric acid values (< 2 mg malonaldehyde/kg). Therefore, use of FreshCase technology in whole muscle beef and ground beef is a viable option to extend storage life.

In the last decade, much attention has been paid to bioremediation of Cr(VI) using various bacterial species. Cr(VI) remediation by indegeneous bacteria isolated from contaminated sites of a tannery industry located in Tamil Nadu, India, was investigated in this study. Three Cr(VI) resistant bacterial strains (TES-1, TEf-1, and TES-2) were isolated and selected based on their Cr(VI) reduction ability in minimal salt medium. Among these three bacterial strains, TES-1 was found to be most efficient in bioreduction, while TES-2 was only found to be Cr(VI) resistant and showed negligible bioreduction, whereas TEf-1 was observed to be most Cr(VI) tolerant. Potential for bioremediation of TES-1 and TEf-1 was further investigated at different concentrations of Cr(VI) in the range of 50 to 350 mg L(-1). TEf-1 showed prominent synchronous growth throughout the experiment, whereas TES-1 took a longer acclimatization time. Minimum inhibitory concentrations (MIC) of Cr(VI) for TES-1 and TEf-1 were approximated as 600 mg L(-1) and 750 mg L(-1), respectively. The kinetic behavior of Cr(VI) reduction by TES-1 and TEf-1 exhibited zero- and first-order removal kinetics for Cr(VI), respectively. The most efficient strain TES-1 was identified as Streptomyces sp. by gene sequencing of 16S rRNA.

Microbial remediation is preferred as a clean and cost-effective method for restoring environments polluted by organics. But the biodegradation rates of hydrophobic organic contaminants (HOCs) are usually extremely restricted by their low bioavailability, especially in soil. Here, a physical method (mechanical mixing) and a chemical method (randomly methylated-β-cyclodextrins, RAMEB) were adopted to improve the bioavailability and biodegradation of polychlorinated biphenyls (PCBs) of an aged soil. The bioavailability of tri-CBs was increased by adding RAMEB in soil/slurry or assisting mechanical mixing in slurry, but these methods had no effects on the bioavailability of tetra-CBs and high chlorinated PCBs (Cl > 4). The degradation rate of tri-CBs could be obviously enhanced by adding RAMEB in soil or assisting mechanical mixing in slurry. The highest removal amount of tri-CBs reached 43.8% in 100 d with a first-order decay kinetics constant of 0.0059 d(-1). But the removal of tetra-CBs and high chlorinated PCBs (Cl > 4) were not significant in all mesocosms, possibly due to the lack or weakness of the native degrading microflora. Based on the analysis of the richness and diversity of bacterial communities, the characteristics of the heatmap and the variation of bphC copy numbers in the soil/slurry mesocosms, it could be inferred that there was no obvious corresponding relationship between the variation of the bacterial communities and the physical/chemical measures., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Aerobic anoxygenic phototrophic (AAP) bacteria are photoheterotrophs that despite their low abundances have been hypothesized to play an ecologically and biogeochemically important role in aquatic systems. Characterizing this role requires a better understanding of the in situ dynamics and activity of AAP bacteria. Here we provide the first assessment of the single-cell activity of freshwater AAP bacteria and their contribution to total bacterial production across lakes spanning a wide trophic gradient, and explore the role of light in regulating AAP activity. The proportion of cells that were active in leucine incorporation and the level of activity per cell were consistently higher for AAP than for bulk bacteria across lakes. As a result, AAP bacteria contributed disproportionately more to total bacterial production than to total bacterial abundance. Interestingly, although environmentally driven patterns in activity did not seem to differ largely between AAP and bulk bacteria, their response to light did, and exposure to light resulted in increases in the proportion of active AAP bacteria with no clear effect on their cell-specific activity. This suggests that light may play a role in the activation of AAP bacteria, enabling these photoheterotrophs to contribute more to the carbon cycle than suggested by their abundance.

This paper investigates the effect of temperature on nitrogen and carbon removal by aerobic granules from landfill leachate with a high ammonium concentration and low concentration of biodegradable organics. The study was conducted in three stages; firstly the operating temperature of the batch reactor with aerobic granules was maintained at 29 °C, then at 25 °C, and finally at 20 °C. It was found that a gradual decrease in operational temperature allowed the nitrogen-converting community in the granules to acclimate, ensuring efficient nitrification even at ambient temperature (20 °C). Ammonium was fully removed from leachate regardless of the temperature, but higher operational temperatures resulted in higher ammonium removal rates [up to 44.2 mg/(L h) at 29 °C]. Lowering the operational temperature from 29 to 20 °C decreased nitrite accumulation in the GSBR cycle. The highest efficiency of total nitrogen removal was achieved at 25 °C (36.8 ± 10.9 %). The COD removal efficiency did not exceed 50 %. Granules constituted 77, 80 and 83 % of the biomass at 29, 25 and 20 °C, respectively. Ammonium was oxidized by both aerobic and anaerobic ammonium-oxidizing bacteria. Accumulibacter sp., Thauera sp., cultured Tetrasphaera PAO and Azoarcus-Thauera cluster occurred in granules independent of the temperature. Lower temperatures favored the occurrence of denitrifiers of Zooglea lineage (not Z. resiniphila), bacteria related to Comamonadaceae, Curvibacter sp., Azoarcus cluster, Rhodobacter sp., Roseobacter sp. and Acidovorax spp. At lower temperatures, the increased abundance of denitrifiers compensated for the lowered enzymatic activity of the biomass and ensured that nitrogen removal at 20 °C was similar to that at 25 °C and significantly higher than removal at 29 °C.

Homoacetogenic bacteria are versatile microbes that use the acetyl coenzyme A (acetyl-CoA) pathway to synthesize acetate from CO2 and hydrogen. Likewise, the acetyl-CoA pathway may be used to incorporate other 1-carbon substrates (e.g., methanol or formate) into acetate or to homoferment monosaccharides completely to acetate. In this study, we analyzed the fractionation of pure acetogenic cultures grown on different carbon substrates. While the fractionation of Sporomusa sphaeroides grown on C1 compounds was strong (εC1, -49‰ to -64‰), the fractionation of Moorella thermoacetica and Thermoanaerobacter kivui using glucose (εGlu= -14.1‰) was roughly one-third as strong, suggesting a contribution of less-depleted acetate from fermentative processes. ForM. thermoacetica, this could indeed be validated by the addition of nitrate, which inhibited the acetyl-CoA pathway, resulting in fractionation during fermentation (εferm= -0.4‰). In addition, we determined the fractionation into microbial biomass of T. kivui grown on H2/CO2(εanabol.= -28.6‰) as well as on glucose (εanabol.= +2.9‰)., (Copyright © 2016, American Society for Microbiology. All Rights Reserved.)

A total of 48,246 microbiological test results were collected from 130 meat processing plants and 220 meat retail facilities over a seven year period: 41 months before and 43 months after HACCP implementation. Our results confirm a strong positive effect of mandatory HACCP implementation on process hygiene indicators in meat establishments. Significant reductions were observed in the number of hygiene indicator organisms on all types of surfaces examined and types of meat establishments investigated. The improvement of process hygiene was articulated as aerobic colony count reduction of at least 1.0 log10 CFU/cm(2) for food contact surfaces and over 2 log10 CFU/cm(2) for cooling facilities (refrigerators, freezers and other meat cooling devices). Meat handlers' hands hygiene was least positively affected. The period after mandatory HACCP implementation was also marked by a steady decline of positive Enterobacteriaceae and Staphylococcus samples. Process hygiene advances for meat processing plants and meat retail facilities were similar., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Prerequisite programs are considered the most efficient tool for a successful implementation of self-control systems to ensure food safety. The main objective of this study was to evaluate the implementation of these programs in 15 catering services located in Navarra and the Basque Country (regions in northern Spain), through on-site audits and microbiological analyses. The implementation of the prerequisite program was incomplete in 60% of the sample. The unobserved temperature control during both the storage and preparation of meals in 20% of the kitchens reveals misunderstanding in the importance of checking these critical control points. A high level of food safety and hygiene (absence of pathogens) was observed in the analyzed meals, while 27.8% of the tested surfaces exceeded the established limit for total mesophilic aerobic microorganisms (≤100 CFU/25 cm²). The group of hand-contact surfaces (oven door handles and aprons) showed the highest level of total mesophilic aerobic microorganisms and Enterobacteriaceae, and the differences observed with respect to the food-contact surfaces (work and distribution utensils) were statistically significant (P < 0.001). With regard to the food workers' hands, lower levels of microorganisms were observed in the handlers wearing gloves (that is, for Staphylococcus spp we identified 43 CFU/cm2 on average compared with 4 CFU/cm2 (P < 0.001) for those not wearing and wearing gloves, respectively). For a proper implementation of the prerequisites, it is necessary to focus on attaining a higher level of supervision of activities and better hygiene training for the food handlers, through specific activities such as informal meetings and theoretical-practical sessions adapted to the characteristics of each establishment., (© 2016 Institute of Food Technologists®)

The influence of common carcass preparation practices of wild red deer on the physicochemical, microbiological and sensory quality of venison was assessed by varying evisceration time and ageing method. Deer were head shot; half were eviscerated 30 min and the other half 4 h post mortem. In both groups (n=18), 6 carcasses were skinned immediately after evisceration and aged for 24 h; 6 were aged unskinned for 24 h and 6 were aged unskinned for 72 h at 10°C. Ageing method had a significant effect on the sensory quality of venison loin; unskinned ageing was associated with an increase of odour and taste intensity, and higher scores for gamey and sweet/caramel flavours. Carcasses aged for 72 h displayed darker and tender meat, but increased aerobic bacterial counts. Evisceration time had less influence on loin quality, although off-flavours were more often detected in deer eviscerated 4h post mortem., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

The aim of this study was to determine the course of effects on the microflora on beef carcasses of a commercial dry chilling process in which carcasses were dry chilled for 3 days. Groups of 25 carcasses selected at random were sampled when the chilling process commenced and after the carcasses were chilled for 1, 2, 4, 6, 8, 24, and 67 h for determination of the numbers of aerobes, coliforms, and Escherichia coli. The temperatures of the surfaces and the thickest part of the hip (deep leg) of carcasses, as well as the ambient air conditions, including air temperature, velocity, and relative humidity (RH), were monitored throughout the chilling process. The chiller was operated at 0°C with an off-coil RH of 88%. The air velocity was 1.65 m/s when the chiller was loaded. The initial RH levels of the air in the vicinity of carcasses varied with the locations of carcasses in the chiller and decreased rapidly during the first hour of chilling. The average times for shoulder surfaces, rump surfaces, and the deep leg of carcasses to reach 7°C were 13.6 ± 3.1, 16.0 ± 2.4 and 32.4 ± 3.2 h, respectively. The numbers of aerobes, coliforms, and E. coli on carcasses before chilling were 5.33 ± 0.42, 1.95 ± 0.77, 1.42 ± 0.78 log CFU/4,000 cm(2), respectively. The number of aerobes on carcasses was reduced by 1 log unit each in the first hour of chilling and in the subsequent 23 h of chilling. There was no significant difference (P > 0.05) between the numbers of aerobes recovered from carcasses after 24 and 67 h of chilling. The total numbers (log CFU/100,000 cm(2)) on carcasses before chilling and after the first hour of chilling were 3.86 and 2.24 for coliforms and 3.30 and 2.04 for E. coli. The subsequent 23 h of chilling reduced the numbers of both groups of organisms by a further log unit. No coliforms or E. coli were recovered after 67 h of chilling. The findings show that the chilling regime investigated in this study resulted in significant reductions of all three groups of indicator organisms.

In the mid-19th century, the dichotomy between aerobic and anaerobic bacteria was introduced. Nevertheless, the aerobic growth of strictly anaerobic bacterial species such as Ruminococcus gnavus and Fusobacterium necrophorum, in a culture medium containing antioxidants, was recently demonstrated. We tested aerobically the culture of 623 bacterial strains from 276 bacterial species including 82 strictly anaerobic, 154 facultative anaerobic, 31 aerobic and nine microaerophilic bacterial species as well as ten fungi. The basic culture medium was based on Schaedler agar supplemented with 1 g/L ascorbic acid and 0.1 g/L glutathione (R-medium). We successively optimized this media, adding 0.4 g/L uric acid, using separate autoclaving of the component, or adding haemin 0.1 g/L or α-ketoglutarate 2 g/L. In the basic medium, 237 bacterial species and ten fungal species grew but with no growth of 36 bacterial species, including 22 strict anaerobes. Adding uric acid allowed the growth of 14 further species including eight strict anaerobes, while separate autoclaving allowed the growth of all tested bacterial strains. To extend its potential use for fastidious bacteria, we added haemin for Haemophilus influenzae, Haemophilus parainfluenzae and Eikenella corrodens and α-ketoglutarate for Legionella pneumophila. This medium allowed the growth of all tested strains with the exception of Mycobacterium tuberculosis and Mycobacterium bovis. Testing primoculture and more fastidious species will constitute the main work to be done, but R-medium coupled with a rapid identification method (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry) will facilitate the anaerobic culture in clinical microbiology laboratories., (Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Autoinducer-2 (AI-2) is a quorum-sensing (QS) molecule which mediates interspecies signaling and affects various bacterial behaviors in food fermentation. Biosynthesis of AI-2 is controlled by S-ribosylhomocysteine lyase encoded by the luxS gene. The objective of this study was to investigate production of AI-2 by aerobic endospore-forming bacteria (AEB) isolated from the West African alkaline fermented seed products Mantchoua and Maari. The study included 13 AEB strains of Bacillus subtilis, B. cereus, B. altitudinis, B. amyloliquefaciens, B. licheniformis, B. aryabhattai, B. safensis, Lysinibacillus macroides and Paenibacillus polymyxa. All the tested strains harbored the luxS gene and all strains except for P. polymyxa B314 were able to produce AI-2 during incubation in laboratory medium. Production of AI-2 by AEB was growth phase dependent, showing maximum activity at the late exponential phase. AI-2 was depleted from the culture medium at the beginning of the stationary growth phase, indicating that the tested AEB possess a functional AI-2 receptor that internalizes AI-2. This study provides the evidences of QS system in Bacillus spp. and L. macroides and new knowledge of AI-2 production by AEB. This knowledge contributes to the development of QS-based strategies for better control of alkaline fermentation., (© FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

It has repeatedly been shown that aryl-hydroxylating dioxygenases do not possess a very high substrate specificity. To gain more insight into this phenomenon, we examined two powerful biphenyl dioxygenases, the well-known wild-type enzyme from Burkholderia xenovorans LB400 (BphA-LB400) and a hybrid enzyme, based on a dioxygenase from Pseudomonas sp. B4-Magdeburg (BphA-B4h), for their abilities to dioxygenate a selection of eight biphenyl analogues in which the second aromatic ring was replaced by aliphatic as well as aliphatic/aromatic moieties, reflecting a variety of steric requirements. Interestingly, both enzymes were able to catalyse transformation of almost all of these compounds. While the products formed were identical, major differences were observed in transformation rates. In most cases, BphA-B4h proved to be a significantly more powerful catalyst than BphA-LB400. NMR characterization of the reaction products showed that the metabolite obtained from biphenylene underwent angular dioxygenation, whereas all other compounds were subject to lateral dioxygenation at ortho and meta carbons. Subsequent growth studies revealed that both dioxygenase source strains were able to utilize several of the biphenyl analogues as sole sources of carbon and energy. Therefore, prototype BphBCD enzymes of the biphenyl degradative pathway were examined for their ability to further catabolize the lateral dioxygenation products. All of the ortho- and meta-hydroxylated compounds were converted to acids, showing that this pathway is quite permissive, enabling catalysis of the turnover of a fairly wide variety of metabolites.

Background: Food spoilage is a process in which the quality parameters decrease and products are no longer edible. This is a cumulative effect of bacteria growth and their metabolite production, which is a factor limiting shelf life. Thus, the aim of the study was to evaluate whether microbiological growth models for total viable count (TVC) and Clostridium strain bacteria are reliable tools for prediction of microbiological changes in spreadable processed cheese., Methods: Investigations were conducted for two types of bacteria: TVC and Clostridium in following temperature: 8°C, 20°C and 30°C. A total number of aerobic bacteria was determined based on standard PN-EN ISO 4833:2004 and Clostridium was detected by using microbiological procedure for sulphite-reducing anaerobic spore-bacteria with a selective nourishment. During the analysis nonlinear regression and Baranyi and Roberts primary model were used., Results: For temperatures 20°C and 30°C, Baranyi and Roberts model, for total viable count showed determination coefficient of 70%. The models prepared for Clostridium, in these temperatures, showed much lower R2, respectively 25% and 30%. At the abovementioned temperatures also the expiration of product shelf life was much shorter and amounted 70 days at 20°C and 7 days at 30°C. For both types of bacteria incubated at 8°C the numbers of bacteria decrease until the expiration of product shelf life., Conclusions: Models used in the analyses, Baranyi and Roberts and nonlinear regression, poorly matched the experimental data, hence they are not reliable tools. Nevertheless, they gave information about dynamic of microbiological changes in spreadable processed cheese.