Search

Listeria are Gram-negative intracellular foodborne pathogens that can cause invasive infections with high mortality rates. In this work, the antibacterial activity of ten essential oils, infusion extracts, and decoction extracts of some medicinal plants was tested against Listeria monocytogenes and listeria ivanovii strains. The effects of different physical conditions including temperature, pH, sodium chloride, and some organic acids were studied. The results showed that the water extracts gave the maximum bacterial inhibition, while ethanolic extract was inactive against the tested Listeria spp. The antibiotic sensitivity of L. monocytogenes LMG10470 and L. ivanovii LMZ11352 was tested against five antibiotics including imipenem, levofloxacin, amikacin, ampicillin, and amoxicillin. Imipenem was the most effective antibiotic, resulting in inhibition zones of 40 mm and 31 mm for L. monocytogenes and L. ivanovii, respectively. When imipenem mixed with Syzygium aromaticum oil, Salvia officinalis oil, Pimpinella anisum infusion, and Mentha piperita infusion each, the water extract of Moringa oleifera leaves and seeds against LMG10470 and LMZ11352 resulted in broader antibacterial activity. The antimicrobial activity of both Pimpinella anisum and Mentha piperita plant extracts is related to a variety of bioactive compounds indicated by gas chromatography–mass spectrometry analysis of these two plant extracts. These two plant extracts seemed to contain many chemical compounds elucidated by gas chromatography–mass spectrometry (GC-MS) and infrared radiation spectra. These compounds could be classified into different chemical groups such as ethers, heterocyclic compounds, aromatic aldehydes, condensed heterocyclic compounds, ketones, alicyclic compounds, aromatics, esters, herbicides, saturated fatty acids, and unsaturated fatty acids. The use of these natural compounds seems to be a useful technological adjuvant for the control of Listeria spp. in foods. [ABSTRACT FROM AUTHOR]

Listeria are Gram-negative intracellular foodborne pathogens that can cause invasive infections with high mortality rates. In this work, the antibacterial activity of ten essential oils, infusion extracts, and decoction extracts of some medicinal plants was tested against Listeria monocytogenes and listeria ivanovii strains. The effects of different physical conditions including temperature, pH, sodium chloride, and some organic acids were studied. The results showed that the water extracts gave the maximum bacterial inhibition, while ethanolic extract was inactive against the tested Listeria spp. The antibiotic sensitivity of L. monocytogenes LMG10470 and L. ivanovii LMZ11352 was tested against five antibiotics including imipenem, levofloxacin, amikacin, ampicillin, and amoxicillin. Imipenem was the most effective antibiotic, resulting in inhibition zones of 40 mm and 31 mm for L. monocytogenes and L. ivanovii, respectively. When imipenem mixed with Syzygium aromaticum oil, Salvia officinalis oil, Pimpinella anisum infusion, and Mentha piperita infusion each, the water extract of Moringa oleifera leaves and seeds against LMG10470 and LMZ11352 resulted in broader antibacterial activity. The antimicrobial activity of both Pimpinella anisum and Mentha piperita plant extracts is related to a variety of bioactive compounds indicated by gas chromatography–mass spectrometry analysis of these two plant extracts. These two plant extracts seemed to contain many chemical compounds elucidated by gas chromatography–mass spectrometry (GC-MS) and infrared radiation spectra. These compounds could be classified into different chemical groups such as ethers, heterocyclic compounds, aromatic aldehydes, condensed heterocyclic compounds, ketones, alicyclic compounds, aromatics, esters, herbicides, saturated fatty acids, and unsaturated fatty acids. The use of these natural compounds seems to be a useful technological adjuvant for the control of Listeria spp. in foods.

Tsegahun Asfaw,1 Deribew Genetu,1 Demissew Shenkute,1 Tassew Tefera Shenkutie,1 Yosef Eshetie Amare,2 Berhanu Yitayew1 1Department of Medical Laboratory Science, Debre Berhan University, Debre Berhan, Ethiopia; 2Department of Biomedical Science, Debre Berhan University, Debre Berhan, EthiopiaCorrespondence: Tsegahun Asfaw, Email tsegahun.asfaw12@gmail.comBackground: Over the years, microbial contamination caused by foodborne bacteria has led to a significant number of food recalls, particularly for meat items that have been related to outbreaks of deadly diseases. Animals often carry Salmonella and Escherichia coli bacteria in their intestines, and these bacteria contaminate raw meat during slaughter. In addition, pathogens such as Staphylococcus aureus can contaminate meat processing equipment and utensils and spread to raw meat.Methods: A cross-sectional study was undertaken between 30 February and 15 March 2022. Sanitary conditions of abattoir and butchers and food handlers’ hygienic practices were assessed using a structured questionnaire. An equal number of meat, swabs from carcasses, knife, weighing balance and cutting board samples (24 each, 120 total) were collected from abattoir and butcher shops. The collected samples were processed for bacterial isolation, antimicrobial susceptibility testing, MDR screening and confirmation, and ESBL screening and confirmation. Finally, SPSS software version 25 was used to compile and analyze the data. Descriptive data from surveys and laboratory procedures were cross-tabulated and summarized using statistical tables and figure.Results: A total of 76 bacteria were isolated from 120 samples. Of all bacteria isolated, S. aureus 16 (21.1%). E. coli 13 (17.1%), and S. epidermidis 12 (15.8%) were the most prevalent. The rate of bacterial contamination was high in meat 18 (23.7%), carcasses 15 (19.7%) and weighing balance 15 (19.7%), respectively. Among the isolates, 18 (23.7%) were resistant for eight and more antibiotics. While, 17 (22.4%), 7(9.2%) and 4(5.3%) of the isolates were resistant for two and three, four and five, and six and seven antibiotics, respectively. Of bacteria isolated, 51/76 (67.1%) were MDR, 23/48 (47.9%) were screened for ESBL production and 13/48 (27.1%) isolates were confirmed as ESBL producer.Conclusion: Multidrug-resistant bacterial contamination was common in meat and meat contact surfaces, which was exacerbated by inadequate sanitation and hygiene practices.Keywords: food-borne bacteria, multidrug-resistant, beta-lactamase, meat, meat contact surfaces

Foodborne diseases as well as Foodborne pathogens are a global issue with significant effects on human health and economy. Therefore, several investigators have tried to find new alternative approaches to prevent and control this problem. In this context, the present study aimed to find some possible and effective approaches for controlling food-borne bacteria via Dill (Anethum graveolens L.) extract (DE) loaded with chitosan nanoparticles (ChNPs) besides its antioxidant and anti-diabetic activities. Flavonoid and phenolic contents of DE were detected by HPLC, indicating the presence of 18 constituents, high content (22526.51 μg/mL) of chlorogenic acid, followed by 2236.21 μg/mL of coumaric acid and 2113.81 μg/mL of pyrocatechol. In contrast, low contents of cinnamic acid, methyl gallate, apigenin, daidzein, quercetin, syringic acid, and kaempferol were detected. B. cereus, Staphylococcus aureus, E. coli, S. typhi, E. faecalis, and C. albicans were highly inhibited by DE loaded ChNPs (DELChNPs) with inhibition zones (IZs) of 28.50 ± 0.87, 30.33 ± 0.58, 29.33 ± 0.58, 23.17 ± 0.76, 25.76 ± 0.58, and 24.17 ± 0.29 mm with MIC 15.41 ± 0.36, 7.70 ± 0.17, 15.58 ± 0.07, 31.08 ± 0.07, 31.04 ± 0.07 and 62.33 ± 0.29 μg/mL compared with inhibitory activity caused by DE, where the IZs were 25.83 ± 1.44, 29.67 ± 0.85, 24.83 ± 0.76, 20.33 ± 1.53, 21.17 ± 0.29, and 19.67 ± 1.15 mm with MIC 62.33 ± 0.29, 31.08 ± 0.07, 62.50 ± 0.29, 31.08 ± 0.07, 31.04 ± 0.07, and 249.0 ± 1.73 μg/mL, respectively. Also, the minimum bactericidal concentration (MBC) of DELChNPs was less than DE against all tested microorganisms. The MBC/MIC index documented that DELChNPs were more effective than DE. The biofilm of tested bacteria was inhibited by DE and DELChNPs but with different levels of anti-biofilm activity. For example, the anti-biofilm activity was 79.26 and 86.15% against B. cereus using DE and DELChNPs, respectively. DELChNPs and DE, compared with the ascorbic acid, exhibited DPPH scavenging % with IC50 values of 7.8 μg/mL, 13.96 μg/mL, and 4.83 μg/mL, respectively. Anti-diabetic activity in vitro via inhibition of amylase indicated that IC50 was 164.2 μg/mL and 164.3 μg/mL using DE and DELChNPs, respectively. This investigation highlights the vital DE phytoconstituents, particularly DELChNPs which possess important therapeutic effects against food-borne microorganisms and could be utilized as a safe alternative to synthetic drugs. [ABSTRACT FROM AUTHOR]

Foodborne diseases as well as Foodborne pathogens are a global issue with significant effects on human health and economy. Therefore, several investigators have tried to find new alternative approaches to prevent and control this problem. In this context, the present study aimed to find some possible and effective approaches for controlling food-borne bacteria via Dill (Anethum graveolens L.) extract (DE) loaded with chitosan nanoparticles (ChNPs) besides its anti-oxidant and anti-diabetic activities. Flavonoid and phenolic contents of DE were detected by HPLC, indicating the presence of 18 constituents, high content (22526.51 μg/mL) of chlorogenic acid, followed by 2236.21 μg/mL of coumaric acid and 2113.81 μg/mL of pyrocatechol. In contrast, low contents of cinnamic acid, methyl gallate, apigenin, daidzein, quercetin, syringic acid, and kaempferol were detected. B. cereus, Staphylococcus aureus, E. coli, S. typhi, E. faecalis, and C. albicans were highly inhibited by DE loaded ChNPs (DELChNPs) with inhibition zones (IZs) of 28.50 ± 0.87, 30.33 ± 0.58, 29.33 ± 0.58, 23.17 ± 0.76, 25.76 ± 0.58, and 24.17 ± 0.29 mm with MIC 15.41 ± 0.36, 7.70 ± 0.17, 15.58 ± 0.07, 31.08 ± 0.07, 31.04 ± 0.07 and 62.33 ± 0.29 μg/mL compared with inhibitory activity caused by DE, where the IZs were 25.83 ± 1.44, 29.67 ± 0.85, 24.83 ± 0.76, 20.33 ± 1.53, 21.17 ± 0.29, and 19.67 ± 1.15 mm with MIC 62.33 ± 0.29, 31.08 ± 0.07, 62.50 ± 0.29, 31.08 ± 0.07, 31.04 ± 0.07, and 249.0 ± 1.73 μg/mL, respectively. Also, the minimum bactericidal concentration (MBC) of DELChNPs was less than DE against all tested microorganisms. The MBC/MIC index documented that DELChNPs were more effective than DE. The biofilm of tested bacteria was inhibited by DE and DELChNPs but with different levels of anti-biofilm activity. For example, the anti-biofilm activity was 79.26 and 86.15% against B. cereus using DE and DELChNPs, respectively. DELChNPs and DE, compared with the ascorbic acid, exhibited DPPH scavenging % with IC50 values of 7.8 μg/mL, 13.96 μg/mL, and 4.83 μg/mL, respectively. Anti-diabetic activity in vitro via inhibition of amylase indicated that IC50 was 164.2 μg/mL and 164.3 μg/mL using DE and DELChNPs, respectively. This investigation highlights the vital DE phytoconstituents, particularly DELChNPs which possess important therapeutic effects against food-borne microorganisms and could be utilized as a safe alternative to synthetic drugs.

Microorganisms assigned as Cronobacter are Gram-negative, facultatively anaerobic, bacteria widely distributed in nature, home environments, and hospitals. They can also be detected in foods, milk powder, and powdered infant formula (PIF). Additionally, as an opportunistic pathogen, Cronobacter may cause serious infections, sometimes leading to the death of neonates and infants. Thus, it is essential to test food products for the presence of Cronobacter spp. The currently used standard described in ISO 22964:2017 is a laborious method that could be easily replaced by surface-enhanced Raman scattering (SERS). Here, we demonstrate that SERS allows the identification of food-borne bacteria belonging to Cronobacter spp. based on their SERS spectra. For this purpose, twenty-six Cronobacter strains from different food samples were analyzed. Additionally, it was shown that it is possible to differentiate them from other closely related pathogens such as Salmonella enterica subsp. enterica , Escherichia coli , or Enterobacter spp. The SERS results were supported by principal component analysis (PCA), as well as and sequencing of 16S rRNA , rpoB and fusA genes. Last but not least, it was demonstrated that the cells of Cronobacter sakazakii may be easily separated from PIF using an appropriate filter, microfluidic chip, and dielectrophoresis (DEP) technique. • The sensitive, non-invasive, rapid, and cost-effective practical prototype applicable in food analysis. • The SERS studies of 52 strains belonging to four genera (Cronobacter, Enterobacter, Salmonella, Escherichia). • SERS-DEP in microfluidic system-based technique for identification of bacterial species at genus and species levels. • PCA enabled the separation of SERS spectra with an accuracy of up to 98 %. • The low concentration detecting and identifying C. sakazakii in real food samples. [ABSTRACT FROM AUTHOR]

Aims The aim of this study was to analyze and compare the prevalence and distribution of resistance genes in Escherichia coli genomes isolated from human clinical samples and animal-based foods worldwide. Methods and results We download from NCBI Pathogen Detection Database the corresponding metadata of the 7,123 E. coli genome to access the information about the antimicrobial resistance gene content. The geographic location and the source of isolation were also obtained and compiled with the antimicrobial resistance gene for statistical analysis, results and discussion. Our criteria considered four groups for analyzing the antimicrobial resistance gene distribution. The first group of genomes from invasive clinical human (ICH) samples from countries with Human Development Index (HDI) ≥ 0.850; the second group of ICH from countries with an HDI ≤ 0.849; the third group of animal-based foods (ABF) from countries with HDI ≥ 0.850 and the fourth group of ABFs from countries with HDI ≤ 0.849. The most prevalent genes in the first group were blaCTX-M-134 (96.53%) and blaCTX-M-27 (86.35%). In the second group, ere(A) (95.96%), soxS (94.49%), qepA8 (90.81%), blaCTX-M-15 (85.66%), and fosA3 (80.88%). In the third group, the most frequently detected were aadA12 (98.5%), ant(3") (89.92%), and blaCARB-2 (87.2%). In the fourth group, aadA12 and aac(3)-IV were identified in 100% of the analyzed genomes. Conclusions It was clear that the use of aminoglycosides in animal production is increasing the selective pressure on micro-organisms in both groups of countries since genes linked to aminoglycoside resistance are related to E. coli from ABF samples. The genomic profile of E. coli from HDI ≥ 0.850 countries indicates a selective pressure aimed at cephalosporins given the high prevalence in both sources. [ABSTRACT FROM AUTHOR]

Background and Objectives: Carotenoid pigments are among the most important pigments and have many applications in various food, cosmetics, hygiene industries and biotechnology. These pigments are produced by plants and microorganisms including Rhodotorula spp. This research intended to study the antimicrobial and antibiofilm effects of the carotenoid pigment from Rhodotorula glutinis on food spoilage bacteria (Staphylococcus aureus and Salmonella Typhimurium). Materials and Methods: The R. glutinis was isolated from milk samples of cows with mastitis and ITS sequence-based typing was performed on them. After extracting the pigment from R. glutinis, its purity was examined using thin-layer chromatography. Following that, the broth microdilution method was used to evaluate antimicrobial effects of the pigment and MtP assay and subsequently scanning electron microscopy were used to assess the antibiofilm effects. In addition, the sub-MIC effects of the pigment on expression of quorum-sensing (QS) genes in S. Typhimurium isolates (sdiA and luxS) and S. aureus isolates (hld) were studied. Finally, the degree of toxicity of the pigment was analyzed using the MTT assay. Results: ITS sequence analysis of R. glutinis revealed that the recently separated isolates exhibited strong differences with the strains recorded in NCBI database in genetic structure. The pigment produced by R. glutinis had strong antimicrobial effects and its mean MIC against S. Typhimurium isolates (17.0 µl.ml-1) was higher than the mean MIC against the S. aureus isolates (4.1 µl.ml-1). Electron microscope images and real-time observations indicated that the sub-MIC values of the pigment suppressed biofilm formation by suppressing expression of QS genes. In addition, the mentioned pigment at high MIC concentrations did not have toxic effects on Vero cells. Conclusion: This research suggests that R. glutinis pigment is effective in destroying the planktonic form of food spoilage bacteria and degrading food spoilage biofilm-forming bacteria. Moreover, considering the low toxicity level of R. glutinis pigment for eukaryotic cells, we can suggest its use as a natural antibacterial preservative in various food materials. [ABSTRACT FROM AUTHOR]

This study aimed to analyse the antibacterial potential of limonene, terpineol, and eugenol for the biofilm reduction of food-borne E. coli, S. aureus and S. typhimurium. A microdilution test with resazurin application was used for the minimum inhibitory concentration and a colony plate count was used for the minimum bactericidal concentration. Biofilm biomass was quantified using the crystal violet assay, while biofilm viability was determined using the plate count method. The results show the highest antibacterial potential among terpenoids for eugenol, followed by terpineol and limonene. Both biomass reduction and viability are strongly dependent on the concentration of all terpenoids tested (p < 0.05). Moreover, eugenol reduced biofilm biomass most effectively (67% for E. coli), while viability was reduced most by terpineol (3.8 log CFU cm−2 for E. coli and S. aureus). The correlation coefficient for the reduction in biomass and viability was highest for eugenol (0.9) and chlorhexidine for all bacteria tested, while the lowest correlation was found for limonene (0.6). Results also demonstrate that tested terpenoids are effective as standard antimicrobial agent chlorhexidine. This suggests that eugenol has potential against food-borne biofilms as it simultaneously reduces both biomass and viability of biofilms. [ABSTRACT FROM AUTHOR]

In recent years, rapid detection methods such as polymerase chain reaction (PCR) and quantitative real-time PCR (qPCR) have been continuously developed to improve the detection of food-borne pathogens in food samples. The recent developments of PCR and qPCR in the detection and identification of these food-borne pathogens are described and elaborated throughout this review. Specifically, further developments and improvements of qPCR are discussed in detecting Salmonella and norovirus. Promising advances in these molecular detection methods have been widely used to prevent human food-borne illnesses and death caused by the food-borne pathogens. In addition, this review presents the limitations and challenges of the detection methods which include conventional culture method and conventional PCR method in detecting Salmonella and norovirus. Furthermore, several advances of qPCR such as viability PCR (vPCR) and digital PCR (dPCR) have been discussed in the detection of Salmonella and norovirus. Good practice of analysis of the food-borne pathogens and other contaminants in the food industry as well as the advancement of molecular detection methods will help improve and ensure food safety and food quality. [ABSTRACT FROM AUTHOR]

Background and Objectives: Carotenoid pigments are among the most important pigments and have many applications in various food, cosmetics, hygiene industries and biotechnology. These pigments are produced by plants and microorganisms including Rhodotorula spp. This research intended to study the antimicrobial and antibiofilm effects of the carotenoid pigment from Rhodotorula glutinis on food spoilage bacteria (Staphylococcus aureus and Salmonella Typhimurium). Materials and Methods: The R. glutinis was isolated from milk samples of cows with mastitis and ITS sequence-based typing was performed on them. After extracting the pigment from R. glutinis, its purity was examined using thin-layer chromatography. Following that, the broth microdilution method was used to evaluate antimicrobial effects of the pigment and MtP assay and subsequently scanning electron microscopy were used to assess the antibiofilm effects. In addition, the sub-MIC effects of the pigment on expression of quorum-sensing (QS) genes in S. Typhimurium isolates (sdiA and luxS) and S. aureus isolates (hld) were studied. Finally, the degree of toxicity of the pigment was analyzed using the MTT assay. Results: ITS sequence analysis of R. glutinis revealed that the recently separated isolates exhibited strong differences with the strains recorded in NCBI database in genetic structure. The pigment produced by R. glutinis had strong antimicrobial effects and its mean MIC against S. Typhimurium isolates (17.0 μl.ml-1) was higher than the mean MIC against the S. aureus isolates (4.1 μl.ml-1). Electron microscope images and real-time observations indicated that the sub-MIC values of the pigment suppressed biofilm formation by suppressing expression of QS genes. In addition, the mentioned pigment at high MIC concentrations did not have toxic effects on Vero cells. Conclusion: This research suggests that R. glutinis pigment is effective in destroying the planktonic form of food spoilage bacteria and degrading food spoilage biofilm-forming bacteria. Moreover, considering the low toxicity level of R. glutinis pigment for eukaryotic cells, we can suggest its use as a natural antibacterial preservative in various food materials.

Foodborne pathogens are one of the major causes of food deterioration and a public health concern worldwide. Antimicrobial peptides (AMPs) encrypted in protein sequences from plants, such as chia (Salvia hispanica), might have a crucial role in the inhibition of bacteria. In this study, the antibacterial activity and stability of chia peptide fractions (CPFs) were evaluated for potential applications in food preservation. Three CPFs (F < 1, F 1-3, and F 3-5 kDa) were obtained by enzymatic hydrolysis of a protein-rich fraction and subsequent ultrafiltration. Gram-positive bacteria were susceptible to F < 1. This fraction's more significant inhibition effect was reported against Listeria monocytogenes (635.4 ± 3.6 µg/mL). F < 1 remained active after incubation at 4–80 °C and a pH range of 5–8 but was inactive after exposure to pepsin and trypsin. In this sense, F < 1 could be suitable for meat and dairy products at a maximum reference level of 12–25 mg/kg. Multicriteria analysis suggested that KLKKNL could be the peptide displaying the antimicrobial activity in F < 1. These results demonstrate the potential of this sequence as a preservative for controlling the proliferation of Gram-positive bacteria in food products. [ABSTRACT FROM AUTHOR]

Lactiplantibacillus (Lpb.) plantarum is a versatile species commonly found in a wide variety of ecological niches including dairy products and vegetables, while it may also occur as a natural inhabitant of the human gastrointestinal tract. Although Lpb. plantarum strains have been suggested to exert beneficial properties on their host, the precise mechanisms underlying these microbe–host interactions are still obscure. In this context, the genome-scale in silico analysis of putative probiotic bacteria represents a bottom–up approach to identify probiotic biomarkers, predict desirable functional properties, and identify potentially detrimental antibiotic resistance genes. In this study, we characterized the bacterial genomes of three Lpb. plantarum strains isolated from three distinct environments [strain IMC513 (from the human GIT), C904 (from table olives), and LT52 (from raw-milk cheese)]. A whole-genome sequencing was performed combining Illumina short reads with Oxford Nanopore long reads. The phylogenomic analyses suggested the highest relatedness between IMC513 and C904 strains which were both clade 4 strains, with LT52 positioned within clade 5 within the Lpb. plantarum species. The comparative genome analysis performed across several Lpb. plantarum representatives highlighted the genes involved in the key metabolic pathways as well as those encoding potential probiotic features in these new isolates. In particular, our strains varied significantly in genes encoding exopolysaccharide biosynthesis and in contrast to strains IMC513 and C904, the LT52 strain does not encode a Mannose-binding adhesion protein. The LT52 strain is also deficient in genes encoding complete pentose phosphate and the Embden–Meyerhof pathways. Finally, analyses using the CARD and ResFinder databases revealed that none of the strains encode known antibiotic resistance loci. Ultimately, the results provide better insights into the probiotic potential and safety of these three strains and indicate avenues for further mechanistic studies using these isolates. [ABSTRACT FROM AUTHOR]

Lactiplantibacillus (Lpb.) plantarum is a versatile species commonly found in a wide variety of ecological niches including dairy products and vegetables, while it may also occur as a natural inhabitant of the human gastrointestinal tract. Although Lpb. plantarum strains have been suggested to exert beneficial properties on their host, the precise mechanisms underlying these microbe–host interactions are still obscure. In this context, the genome-scale in silico analysis of putative probiotic bacteria represents a bottom–up approach to identify probiotic biomarkers, predict desirable functional properties, and identify potentially detrimental antibiotic resistance genes. In this study, we characterized the bacterial genomes of three Lpb. plantarum strains isolated from three distinct environments [strain IMC513 (from the human GIT), C904 (from table olives), and LT52 (from raw-milk cheese)]. A whole-genome sequencing was performed combining Illumina short reads with Oxford Nanopore long reads. The phylogenomic analyses suggested the highest relatedness between IMC513 and C904 strains which were both clade 4 strains, with LT52 positioned within clade 5 within the Lpb. plantarum species. The comparative genome analysis performed across several Lpb. plantarum representatives highlighted the genes involved in the key metabolic pathways as well as those encoding potential probiotic features in these new isolates. In particular, our strains varied significantly in genes encoding exopolysaccharide biosynthesis and in contrast to strains IMC513 and C904, the LT52 strain does not encode a Mannose-binding adhesion protein. The LT52 strain is also deficient in genes encoding complete pentose phosphate and the Embden–Meyerhof pathways. Finally, analyses using the CARD and ResFinder databases revealed that none of the strains encode known antibiotic resistance loci. Ultimately, the results provide better insights into the probiotic potential and safety of these three strains and indicate avenues for further mechanistic studies using these isolates.

One hundred fifty samples were read to eat chicken meaty collected from different restaurants in Luxor city to evaluate bacteriological quality RTE chicken meat. The mean values of APC, Coliform, Staphylococcus counts, Anaerobic count, Yeast count, Mould count (cfu/g). 1.36X1042.94X103&8.42x1023.90x102,4.671.15&1.000.73&7.672.23,2.671.26 to chicken shawirma without addition, 5.58X1031.16X103&3.34x1029.82x10&2.33 1.24&1.000.75&8.332.40&2.671.26 for chicken burger without addition and 4.62X1037.42X102&1.53x1024.85x10&1.330.79&3.001.37&4.331.64,1.670.84 for fried chicken, all samples not detected for Shigella, respectively.9 E.coli (6%) were isolated from samples represented 4(8%), (2) O125:H2, (1) O143:H8 and (1) O111:H1 from chicken shawirma without addition, 3(6%) O55: H2, O158:H3and O86a:H1 from chicken burger without addition, 2 (4%) O142:H3, O26:H1from fried chicken, Also, 8(5.33%) Coagulase positive Staphylococcus aureus were isolated from samples. Represented as 4(8%) isolate from chicken shawirma without addition, 3 (6%) from chicken burger without addition, 1(2%) from fried chicken. 6(4%) of Salmonella were isolated from Samples represented as 2(4%) S. typhimurium and 1(2%) S. enteritidis from shawirma without addition, 1(2%)S. enteritidis and 1(2%) S. Anatum from chicken burger without addition, 1(2%) S.Kentucky from fried chicken. Isolates. Most of E.coli isolate sensitive for Colistin sulphate(10ug) and Nalidixic acid(10ug). St.aureus isolates sensitive to Ampicillin (10ug) and Vancomycin (15ug). Most of Salmonella isolate sensitive for Gentamycin (10ug), Colistin Sulphate(10ug) and Ceftriaxone. [ABSTRACT FROM AUTHOR]

Aim: The present study was undertaken to determine bacterial load as well as characterize bacterial flora of ready to eat (RTE) betel leaf sold at local markets in Mymensingh city. Materials and Methods: A total of 25 RTE betel leaf samples were collected from five local markets such as Kamal-Ranjit (KR) market, Shesh more, Kewatkhali, Jobber more, and Ganginar par. Results: Total viable count of bacteria in betel leaf (log10 mean colony forming unit±standard deviation/ml) was 7.58±0.04 for KR market, 7.72±0.06 for Shesh more, 7.62±0.04 for Kewatkhali, 7.40±0.03 for Jobber more, and 7.60±0.06 for Ganginar par. A total of 98 bacterial isolates belong to five genera (Escherichia coli, Salmonella spp., Vibrio spp., Bacillus spp., and Staphylococcus spp.) were identified. The prevalence of E. coli was 17.34%, Salmonella spp. was 25.51%, Vibrio spp. was 19.39%, Bacillus spp. was 18.37%, and Staphylococcus spp. was 19.39%. Antibiotic sensitivity test showed that all isolates were sensitive to two antibiotics such as ciprofloxacin and gentamicin. Four isolates (E. coli, Salmonella spp., Vibrio spp., and Staphylococcus spp.) were resistant to two antibiotics (ampicillin and cephalexin). Antibiogram profile of bacterial isolates of betel leaf suggests that they were multidrug resistance. Conclusion: Data of this study indicate that betel leaf sold at local market harbors multidrug resistance food-borne bacteria which might cause public health hazards if these antibiotic resistant transfer to human through food chain.

We present a fully integrated portable centrifugal microsystem for multiplex detection of food poisoning bacteria with a large volume of sample up to 1 mL. The microsystem consists of a portable genetic analyzer and a fully integrated centrifugal microdevice. The centrifugal microdevice is designed with two units: a 3D printed solution-loading cartridge and a centrifugal microfluidic disc. All the essential solutions for loop-mediated isothermal amplification (LAMP) reaction are stored inside the cartridge, and orderly released into centrifugal microdevice by a rotation program. Each unit of the device is designed with 20 reaction chambers for simultaneous detection of food-borne bacteria in one test. To increase the amount of a sample to 1 mL, we incorporated the super absorbent polymer (SAP) in the waste chamber to absorb the sample and the washing solution during the device operation. The whole process was automatically conducted including designated solution release, bead-based DNA extraction, isothermal gene amplification by Eriochrome Black (EBT)-mediated LAMP reaction, and colorimetric and UV–visible detection of amplicons. The ratio between Abs 640nm and Abs 570nm was used as a criterion to confirm the positive result, and the result was positive upon the condition of Abs 640 /Abs 570 ≥ 1.0. To demonstrate the pathogenic bacteria detection on our proposed microsystem, we targeted three kinds of bacteria (Escherichia coli O157:H7, Salmonella typhimurium , and Vibrio parahaemolyticus) for monoplex and multiplex detection. The whole process from sample to result was completed within 1 h with a low limit of detection (LOD) of 102 cells/mL. • A fully integrated centrifugal microfluidic device for POC DNA diagnostics is presented. • Super absorption polymer (SAP) integration enables to handle 1 mL volume of a sample. • A 3D-printed sample loading cartridge is combined for full automation of solution injection. • A portable genetic analyzer is proposed for POCT. • Sample-to-answer diagnostics of food-borne pathogens are demonstrated with low LOD. [ABSTRACT FROM AUTHOR]

Highlights • Eight compounds were isolated. • Asparagine was first isolated from fruit of P. mume. • Ethyl acetate extract showed best inhibitory activities, better than the total extract. • Citric acid, chlorogenic acid, asparagine showed excellent anti-bacterial activities. Abstract Prunus mume has good antibacterial activity in addition to its high nutrition and many medical functions. In order to determine which components play domain role in fruit of Prunus mume , the antibacterial activities of five extracts (total, CHCl 3 , ethyl acetate, n -butanol and water) and eight compounds (squalene, epicatechin, chlorogenic acid, isoquercitrin, citric acid, rutin, amygdalin, and asparagine) against five food-borne bacteria (Salmonella enterica , Listeria monocytogenes, Staphylococcus aureus , Bacillus cereus , and Escherichia coli) were measured through agar plate drilling method. The ethyl acetate extract showed the highest inhibitory activities. At a concentration of 50 mg/mL, citric acid isolated from an ethyl acetate extract had superior activities against all five bacteria, compared with the other compounds. Chlorogenic acid, also isolated from the ethyl acetate extract, inhibited four of the five bacteria. Epicatechin, isolated from the ethyl acetate extract, inhibited Listeria monocytogenes and Salmonella enterica , while isoquercetrin, isolated from the ethyl acetate extract, and asparagine, isolated from the n -butanol extract, inhibited Listeria monocytogenes only. The results hinted citric acid, chlorogenic acid, epicatechin, isoquercetrin and asparagine were the compounds playing domain role on the antibiotic activities of Prunus mume against the five bacteria. [ABSTRACT FROM AUTHOR]

Blue light primarily exhibits antimicrobial activity through the activation of endogenous photosensitizers, which leads to the formation of reactive oxygen species that attack components of bacterial cells. Current data show that blue light is innocuous on the skin, but may inflict photo-damage to the eyes. Laboratory measurements indicate that antimicrobial blue light has minimal effects on the sensorial and nutritional properties of foods, although future research using human panels is required to ascertain these findings. Food properties also affect the efficacy of antimicrobial blue light, with attenuation or enhancement of the bactericidal activity observed in the presence of absorptive materials (for example, proteins on meats) or photosensitizers (for example, riboflavin in milk), respectively. Blue light can also be coupled with other treatments, such as polyphenols, essential oils and organic acids. While complete resistance to blue light has not been reported, isolated evidence suggests that bacterial tolerance to blue light may occur over time, especially through gene mutations, although at a slower rate than antibiotic resistance. Future studies can aim at characterizing the amount and type of intracellular photosensitizers across bacterial species and at assessing the oxygen-independent mechanism of blue light—for example, the inactivation of spoilage bacteria in vacuum-packed meats.

The use of antimicrobial growth promoters (AGPs) in sub-therapeutic doses for long periods promotes the selection of resistant microorganisms and the subsequent risk of spreading this resistance to the human population and the environment. Global concern about antimicrobial resistance development and transference of resistance genes from animal to human has been rising. The goal of our research was to evaluate the susceptibility pattern to different classes of antimicrobials of colistin-resistant Escherichia coli from poultry production systems that use AGPs, and characterize the resistance determinants associated to transferable platforms. E. coli strains (n = 41) were obtained from fecal samples collected from typical Argentine commercial broiler farms and susceptibility for 23 antimicrobials, relevant for human or veterinary medicine, was determined. Isolates were tested by PCR for the presence of mcr-1, extended spectrum β-lactamase encoding genes and plasmid-mediated quinolone resistance (PMQR) coding genes. Conjugation and susceptibility patterns of the transconjugant studies were performed. ERIC-PCR and REP-PCR analysis showed a high diversity of the isolates. Resistance to several antimicrobials was determined and all colistin-resistant isolates harbored the mcr-1 gene. CTX-M-2 cefotaximase was the main mechanism responsible for third generation cephalosporins resistance, and PMQR determinants were also identified. In addition, co-transference of the qnrB determinant on the mcr-1-positive transconjugants was corroborated, which suggests that these resistance genes are likely to be located in the same plasmid. In this work a wide range of antimicrobial resistance mechanisms were identified in E. coli strains isolated from the environment of healthy chickens highlighting the risk of antimicrobial abuse/misuse in animals under intensive production systems and its consequences for public health.

Titanium dioxide (TiO2) is commonly used as a food additive (E171 in the EU) for its whitening and opacifying properties. However, a risk of intestinal barrier disruption, including dysbiosis of the gut microbiota, is increasingly suspected because of the presence of a nano-sized fraction in this additive. We hypothesized that food-grade E171 and Aeroxyde P25 (identical to the NM-105 OECD reference nanomaterial in the European Union Joint Research Centre) interact with both commensal intestinal bacteria and transient food-borne bacteria under non-UV-irradiated conditions. Based on differences in their physicochemical properties, we expect a difference in their respective effects. To test these hypotheses, we chose a panel of eight Gram-positive/Gram-negative bacterial strains, isolated from different biotopes and belonging to the species Escherichia coli, Lactobacillus rhamnosus, Lactococcus lactis (subsp. lactis and cremoris), Streptococcus thermophilus, and Lactobacillus sakei. Bacterial cells were exposed to food-grade E171 vs. P25 in vitro and the interactions were explored with innovative (nano)imaging methods. The ability of bacteria to trap TiO2 was demonstrated using synchrotron UV fluorescence imaging with single cell resolution. Subsequent alterations in the growth profiles were shown, notably for the transient food-borne L. lactis and the commensal intestinal E. coli in contact with food-grade TiO2. However, for both species, the reduction in cell cultivability remained moderate, and the morphological and ultrastructural damages, observed with electron microscopy, were restricted to a small number of cells. E. coli exposed to food-grade TiO2 showed some internalization of TiO2 (7% of cells), observed with high-resolution nano-secondary ion mass spectrometry (Nano-SIMS) chemical imaging. Taken together, these data show that E171 may be trapped by commensal and transient food-borne bacteria within the gut. In return, it may induce some physiological alterations in the most sensitive species, with a putative impact on gut microbiota composition and functioning, especially after chronic exposure.

The use of antimicrobial growth promoters (AGPs) in sub-therapeutic doses for long periods promotes the selection of resistant microorganisms and the subsequent risk of spreading this resistance to the human population and the environment. Global concern about antimicrobial resistance development and transference of resistance genes from animal to human has been rising. The goal of our research was to evaluate the susceptibility pattern to different classes of antimicrobials of colistin-resistant Escherichia coli from poultry production systems that use AGPs, and characterize the resistance determinants associated to transferable platforms. E. coli strains (n = 41) were obtained from fecal samples collected from typical Argentine commercial broiler farms and susceptibility for 23 antimicrobials, relevant for human or veterinary medicine, was determined. Isolates were tested by PCR for the presence of mcr-1, extended spectrum β-lactamase encoding genes and plasmid-mediated quinolone resistance (PMQR) coding genes. Conjugation and susceptibility patterns of the transconjugant studies were performed. ERIC-PCR and REP-PCR analysis showed a high diversity of the isolates. Resistance to several antimicrobials was determined and all colistin-resistant isolates harbored the mcr-1 gene. CTX-M-2 cefotaximase was the main mechanism responsible for third generation cephalosporins resistance, and PMQR determinants were also identified. In addition, co-transference of the qnrB determinant on the mcr-1-positive transconjugants was corroborated, which suggests that these resistance genes are likely to be located in the same plasmid. In this work a wide range of antimicrobial resistance mechanisms were identified in E. coli strains isolated from the environment of healthy chickens highlighting the risk of antimicrobial abuse/misuse in animals under intensive production systems and its consequences for public health. [ABSTRACT FROM AUTHOR]

Titanium dioxide (TiO2) is commonly used as a food additive (E171 in the EU) for its whitening and opacifying properties. However, a risk of intestinal barrier disruption, including dysbiosis of the gut microbiota, is increasingly suspected because of the presence of a nano-sized fraction in this additive. We hypothesized that food-grade E171 and Aeroxyde P25 (identical to the NM-105 OECD reference nanomaterial in the European Union Joint Research Centre) interact with both commensal intestinal bacteria and transient food-borne bacteria under non-UV-irradiated conditions. Based on differences in their physicochemical properties, we expect a difference in their respective effects. To test these hypotheses, we chose a panel of eight Grampositive/ Gram-negative bacterial strains, isolated from different biotopes and belonging to the species Escherichia coli, Lactobacillus rhamnosus, Lactococcus lactis (subsp. lactis and cremoris), Streptococcus thermophilus, and Lactobacillus sakei. Bacterial cells were exposed to food-grade E171 vs. P25 in vitro and the interactions were explored with innovative (nano)imaging methods. The ability of bacteria to trap TiO2 was demonstrated using synchrotron UV fluorescence imaging with single cell resolution. Subsequent alterations in the growth profiles were shown, notably for the transient foodborne L. lactis and the commensal intestinal E. coli in contact with food-grade TiO2. However, for both species, the reduction in cell cultivability remained moderate, and the morphological and ultrastructural damages, observed with electron microscopy, were restricted to a small number of cells. E. coli exposed to food-grade TiO2 showed some internalization of TiO2 (7% of cells), observed with high-resolution nano-secondary ion mass spectrometry (Nano-SIMS) chemical imaging. Taken together, these data show that E171 may be trapped by commensal and transient food-borne bacteria within the gut. In return, it may induce some physiological alterations in the most sensitive species, with a putative impact on gut microbiota composition and functioning, especially after chronic exposure. [ABSTRACT FROM AUTHOR]

Dihydromyricetin (DMY) has recently attracted increased interest due to its considerable health-promoting activities but there are few reports on its antibacterial activity and mechanism. In this paper, the activity and mechanisms of DMY from Ampelopsis grossedentata leaves against food-borne bacteria are investigated. Moreover, the effects of pH, thermal-processing, and metal ions on the antibacterial activity of DMY are also evaluated. The results show that DMY exhibits ideal antibacterial activity on five types of food-borne bacteria (Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Salmonella paratyphi, and Pseudomonas aeruginosa). The activities of DMY against bacteria are extremely sensitive to pH, thermal-processing, and metal ions. The morphology of the tested bacteria is changed and damaged more seriously with the exposure time of DMY. Furthermore, the results of the oxidative respiratory metabolism assay and the integrity of the cell membrane and wall tests revealed that the death of bacteria caused by DMY might be due to lysis of the cell wall, leakage of intracellular ingredients, and inhibition of the tricarboxylic acid cycle (TCA) pathway.

The aim of the study was to evaluate possible antibacterial and antibiofilm efficacy of a bacteriocin, nisin with two essential oil components linalool and p-coumaric acid in combination against food-borne bacteria Bacillus cereus and Salmonella typhimurium. Their inhibition effects on planktonic cells and preformed biofilms were evaluated using microbroth dilution and checkerboard titration methods. Nisin/ p-coumaric acid combination showed synergistic effects against planktonic cells of both the studied bacteria, whereas nisin/linalool combination showed synergistic activity against B. cereus and additive effect against S. typhimurium. In preformed biofilms, nisin by itself failed to show >50% antibiofilm efficacy against both the studied bacteria, but in combination with linalool and p-coumaric acid, it exerted >50% antibiofilm efficacy. On the basis of fractional inhibitory concentration indices values, nisin/ p-coumaric acid combination exhibited synergistic antibiofilm activity, whereas nisin/linalool combination showed additive effects against preformed biofilms of studied bacteria. The results provide evidence that p-coumaric acid due to its synergistic interactions with nisin against planktonic cells and biofilms of both Gram-positive and Gram-negative food-borne bacteria enhanced the antibacterial spectrum of nisin, which subsequently may facilitate their use in the food industry. Significance and Impact of the Study In the present work, synergistic interactions between a bacteriocin, nisin and essential oil component p-coumaric acid on planktonic cells as well as on biofilms of Gram-positive and Gram-negative food-borne bacteria have been reported. The results of this study provide evidence that nisin / p-coumaric acid combination can be considered as a promising source for development of more potent broad spectrum antimicrobial blend for food preservation, which subsequently may facilitate their use in the food industry. To the best of our knowledge, this is the first report of the antibacterial and antibiofilm efficacy of nisin in combination with essential oil components against food-borne bacteria. [ABSTRACT FROM AUTHOR]

The aim of the study was to assess the in vitro effect of phenols extracted from oil vegetation water (PEOW) on several food-borne strains. Antibacterial activity of PEOW was based on the minimum bactericidal concentration (MBC) on microtitre assay. The taxa tested were: Staphylococcus (n. 5), Listeria (n. 4), Escherichia (n. 2), Salmonella (n. 1), Pseudomonas (n. 3), Lactobacillus (n. 2) and Pediococcus (n. 1). S. aureus and L. monocytogens showed the lowest level of resistance to PEOW (MBC=1.5-3 mg/mL). In contrast, the Gram negative strains (e.g. S. Typhimurium and Pseudomonas spp.) were in some cases unaffected by the tested doses and the MBCs ranged between 6 to 12 mg/mL. Starter cultures were dramatically reduced on growth (e.g. Staphylococcus xylosus; 0.75 mg/mL MBC). The thresholds for pathogenic strains could be considered for further applications of PEOW in food models (e.g. shelf life or challenge test studies).

The antimicrobial activities of Lawsonia inermis leaf extract and 2-hydroxy-1,4-naphthoquinone analogues against food-borne bacteria. The antimicrobial activities of five fractions derived from the methanol extract of Lawsonia inermis leaves were evaluated against 7 food-borne bacteria. 2-Hydroxy-1,4-naphthoquinone was isolated by chromatographic analyses. 2-Hydroxy-1,4-naphthoquinone showed the strong activities against Bacillus cereus, Listeria monocytogenes, Salmonella enterica, Shigella sonnei, Staphylococcus epidermidis, and S. intermedius, but exerted no growth-inhibitory activities against S. typhimurium. The antimicrobial activities of the 2-hydroxy-1,4-naphthoquinone analogues were tested against 7 food-borne bacteria to establish structure-activity relationships. Hydroxyl (2-hydroxy-1,4-naphthoquinone and 5-hydroxy-1,4-naphthoquinone), methoxy (2-methoxy-1,4-naphthoquinone), and methyl (2-methyl-1,4-naphthoquinone, and 5-hydroxy-2-methyl-1,4-naphthoquinone) functional groups on the 1,4-naphthoquinone skeleton possessed potent activities, whereas bromo (2-bromo-1,4-naphthoquinone and 2,3-dibromo-1,4-naphthoquione) and chloro (2,3-dichloro-1,4-naphthoquinone) exhibited no activity against 7 food-borne bacteria. The L. inermis leaf extract and 2-hydroxy-1,4-naphthoquinone analogues should be useful as natural antimicrobial agents against food-borne bacteria. [ABSTRACT FROM AUTHOR]

Kefir is a fermented milk product produced by kefir grains traditionally or lyophilized starter culture. Some quality characteristics of kefir produced at 22 °C and 30 °C using kefir grains after addition of microbial levan and pullulan were investigated for 14 days. Additionally, the survival of different Gram-positive and Gram-negative bacteria strains which were inoculated before and after fermentation were investigated during storage. The pH and titratable acidity were in the ranges of 4.67–4.39 and 1.10–0.87%, respectively. The highest exopolysaccharide values (458.3–465.3 mg/kg) were found in the samples produced with the addition of 1% (w/v) of microbial levan at 30 °C. Yeast counts were in the ranges of 6.73–5.11 log CFU/mL while the lactobacilli and lactic streptococci counts were in the ranges of 9.64–7.91 and 9.64–8.69 log CFU/mL, respectively. The microbial polysaccharide addition did not show any significant differences in the enumeration of lactic acid bacteria in kefir (p > 0.05). All Gram-positive and Gram-negative bacteria grew/survived during fermentation however Listeria monocytogenes was the most susceptible test bacterium to metabolites during storage. The highest reduction in the counts of L. monocytogenes was determined as 2.39 log units after 24 h of fermentation at 30 °C in the samples which were inoculated before fermentation and produced with the addition of pullulan. Kefir samples produced at 30 °C without polysaccharide addition were considered as the best with respect to appearance, taste, consistency and overall acceptability. [ABSTRACT FROM AUTHOR]

Background Plants harbor a diverse bacterial community, both as epiphytes on the plant surface and as endophytes within plant tissue. While some plant-associated bacteria act as plant pathogens or promote plant growth, others may be human pathogens. The aim of the current study was to determine the bacterial community composition of organic and conventionally grown leafy salad vegetables at the point of consumption using both culture-dependent and cultureindependent methods. Results Total culturable bacteria on salad vegetables ranged from 8.0 × 103 to 5.5 × 108 CFU g-1. The number of culturable endophytic bacteria from surface sterilized plants was significantly lower, ranging from 2.2 × 103 to 5.8 × 105 CFU g-1. Cultured isolates belonged to six major bacterial phyla, and included representatives of Pseudomonas, Pantoea, Chryseobacterium, and Flavobacterium. Eleven different phyla and subphyla were identified by cultureindependent pyrosequencing, with Gammaproteobacteria, Betaproteobacteria, and Bacteroidetes being the most dominant lineages. Other bacterial lineages identified (e.g. Firmicutes, Alphaproteobacteria, Acidobacteria, and Actinobacteria) typically represented less than 1% of sequences obtained. At the genus level, sequences classified as Pseudomonas were identified in all samples and this was often the most prevalent genus. Ralstonia sequences made up a greater portion of the community in surface sterilized than non-surface sterilized samples, indicating that it was largely endophytic, while Acinetobacter sequences appeared to be primarily associated with the leaf surface.. Analysis of molecular variance indicated there were no significant differences in bacterial community composition between organic versus conventionally grown, or surface-sterilized versus non-sterilized leaf vegetables. While culture-independent pyrosequencing identified significantly more bacterial taxa, the dominant taxa from pyrosequence data were also detected by traditional culturedependent methods. Conclusions The use of pyrosequencing allowed for the identification of low abundance bacteria in leaf salad vegetables not detected by culture-dependent methods. The presence of a range of bacterial populations as endophytes presents an interesting phenomenon as these microorganisms cannot be removed by washing and are thus ingested during salad consumption. [ABSTRACT FROM AUTHOR]

The germicidal efficacy of six sanitizers against food-borne bacteria and spores ( Escherichia coli, Salmonella Typhimurium, Staphylococcus aureus, Pseudomonas aeruginosa, and Bacillus subtilis spores) and the effect of these sanitizers in simulation of cleaning and sterilizing in place were evaluated. The most effective sanitizer solution was peracetic acid (PAA), which was capable of reducing E. coli populations by more than 5 log CFU/g at 60 mg/L. The rest of the sanitizers resulted in a population reduction of less than 5 log CFU/g at 150 mg/L in phenol coefficient test. The effect of acid-anionic sanitizer (ABF) and PAA against E. coli and S. aureus was affected by both pH and temperature. The synergism of sanitizers on germicidal efficacy has also been examined in this study. It was observed that the combination of PAA and ABF presented high efficacy against spores of B. subtilis. 0.2 % PAA in combination with 0.1 % ABF reduced 7.6 log spores. The simulation of cleaning-in-place (CIP) and sterilization-in-place (SIP) revealed that most of organisms were eliminated during CIP. B. subtilis spores holding strong attachment and heat resistance could be eliminated with the combination of 0.2 % PAA and 0.1 % ABF. These findings showed that germicidal efficacy against bacteria and spores was affected by the type of sanitizer, concentration, and environmental conditions, which provides the guidelines in lowering the concentration of sanitizers through synergistic activity and further may be valuable references for sanitation to compete the cycle of good hygiene practices in a proper CIP/SIP process. [ABSTRACT FROM AUTHOR]

Abstract: The main products of Myristica fragrans are the dried seed (nutmeg) and aril (mace), which are used as spices or condiments to flavor foods. In this study, its leaf and different parts of fruit (pericarp, aril, seed-kernel and shell) were compared for their total phenolic content, antioxidant and anti food-borne bacterial capacities. The 80% methanol extracts of aril, seed-kernel and shell shared the highest total phenolic content with shell extract acted as the greatest primary antioxidant, by having the highest ferric reducing antioxidant power (FRAP) activity (EC50 9.7±0.1μg/mL), β-carotene-bleaching activity (EC50 21.5±2.7μg/mL) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity (EC50 160.9±13.9μg/mL), whereas the pericarp extract exhibited highest secondary antioxidant activity as a metal chelator (EC50 75.6±14.4μg/mL). Only the aril and seed-kernel extracts were found to inhibit the food-borne bacteria with the lowest minimum inhibition concentration of 50μg/mL, against Staphylococcus aureus (ATCC12600) and Bacillus cereus (ATCC10876). Our findings suggest the possibility of using the aril and seed-kernel extracts as natural food preservative and other parts as a new source of natural antioxidant for food and pharmaceutical industries. [Copyright &y& Elsevier]

The aim of this study was to determine the main constituents of the essential oil isolated from Fortunella crassifolia Swingle peel by hydro-distillation, and to test the efficacy of the essential oil on antimicrobial activity. Twenty-five components, representing 92.36% of the total oil, were identified by GC-MS analysis. The essential oil showed potent antimicrobial activity against both Gram-negative (E. coli and S. typhimurium) and Gram-positive (S. aureus, B. cereus, B. subtilis, L. bulgaricus, and B. laterosporus) bacteria, together with a remarkable antifungal activity against C. albicans. In a food model of beef extract, the essential oil was observed to possess an effective capacity to control the total counts of viable bacteria. Furthermore, the essential oil showed strongly detrimental effects on the growth and morphological structure of the tested bacteria. It was suggested that the essential oil from Fortunella crassifolia Swingle peel might be used as a natural food preservative against bacteria or fungus in the food industry. [ABSTRACT FROM AUTHOR]

Abstract: The antibacterial activity of water-soluble extract from pine needles of Cedrus deodara (WEC) was evaluated on five food-borne bacteria, and its related mechanism was investigated by transmission electron microscope. In vitro antibacterial assay showed that WEC possesses a remarkable antibacterial activity against tested food-borne bacteria including Escherichia coli, Proteus vulgaris, Staphylococcus aureus, Bacillus subtilis and Bacillus cereus, with the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values in the ranges of 0.78–12.5mg/ml and 1.56–25mg/ml, respectively. In a food system of fresh-squeezed tomato juice, WEC was observed to possess an effective capacity to control the total counts of viable bacteria. Shikimic acid was isolated from WEC and identified as the main antibacterial compound. All results of our study suggested that WEC might be a new potential source of natural antibacterial agents applicable to food. [Copyright &y& Elsevier]

Abstract: Carvacrol is a major component in some essential oils such as oregano and thyme and its inhibitory effect on the growth of various microorganisms is well documented. However, the active mechanism of carvacrol, as well as that of other essential oil components, has not yet been fully established and has generally not been well investigated. In this study, the antimicrobial activity of carvacrol against some Gram-positive and Gram-negative food-related bacterial strains was preliminarily verified and the effect of carvacrol on their cell envelope was further investigated by atomic force microscopy analysis. The atomic force microscopy images of the cells treated with carvacrol 3.3 mM for 1 h were analyzed by anappropriate software in order to visualize the effect of the treatment and to determine the values of cell surface roughness and some biometric parameters (cell length and width). The results showed that all microorganisms tested were sensitive to carvacrol both in solid and liquid media. Furthermore, images of cells of all strains treated with carvacrol exhibited appreciable modifications, indicating a change in cell surface structure. Finally, both length and diameter of the microorganisms decreased after contact with carvacrol. [Copyright &y& Elsevier]

Background: The present study aimed to determine the occurrence of human disease-causing enteric bacteria on raw vegetables, fruits, meats, and milk products sold in Indian markets. The study further aimed to analyze antibiotic resistance rates and the presence of blaCTX-M, blaTEM, blaSHV, and blaAmpC. Methodology: Twenty-three food-borne and 23 clinical isolates were compared for antibiotic resistance rates and the presence of blaCTX-M, blaTEM, blaSHV, and blaAmpC. Swabs were taken from unwashed and washed food items, as well as from some chopped food specimens, and inoculated on appropriate culture medium. Bacterial isolates were identified, antibiotic susceptibility was performed, and bla genes were detected by PCR. Results: Thirty-eight bacterial isolates were obtained from the food specimens, of which 36 (94.7%) were Gram-negative and two (5.3%) were Gram-positive bacterial species. Klebsiella pneumoniae was the most prevalent (52.6%; 20/38) bacterial species isolated, followed by Citrobacter koseri (18.4%; 7/38). In food isolates, the majority of the isolates were resistant to gentamicin (33.3%) followed by amikacin (11.1%). Resistance to a third-generation cephalosporin was noticed in only 5.6% isolates. However, in clinical isolates, maximal resistance was noticed against third-generation cephalosporins followed by ofloxacin in 91.3% and 86.9% isolates, respectively, and resistance to gentamicin and amikacin was noticed in 78.3% and 52.2% isolates, respectively. The presence of blaCTX-M, blaTEM, blaSHV, and blaampC in clinical isolates was noticed in 52.2%, 60.9%, 21.7%, and 43.5%, respectively. None of the isolates from food showed the presence of any of the above-cited genes. Conclusions: Probably bla genes have not yet disseminated to raw-food vegetation in India. [ABSTRACT FROM AUTHOR]

Abstract: Repetitive extragenic palindromic sequence-based PCR (rep-PCR) utilizing a semi-automated system, was evaluated as a method to determine Salmonella serotypes. A group of 216 Salmonella isolates belonging to 13 frequently isolated serotypes and one rarer serotype from poultry were used to create a DNA fingerprint library with the DiversiLab™ System software. Subsequently, a blinded set of 44 poultry isolates were fingerprinted and queried against the library in an attempt to putatively assign a serotype designation to each Salmonella isolate. The query isolates were previously typed employing standard serological techniques. Utilizing pair-wise similarity percentages as calculated by the Pearson correlation coefficient, the predicted serotype of 28 isolates matched the serological typing result. For eight isolates, rep-PCR results were interpreted as one of two very closely-related serotypes, Hadar and the rarer Istanbul. Traditional serological assays have difficulty distinguishing between these groups, and sequencing interspacer regions of the rrfH gene was unable to differentiate among isolates of these two serovars. Six of the remaining isolates resulted in no match to the database (similarity values <95%) and these indeed proved to be serotypes not included in the original library. The two remaining samples proved discrepant at the 95% similarity threshold, however examination of electropherograms clearly indicated fingerprint variability between query and library samples, suggesting an expanded rep-PCR library will be necessary for increased utility. Since serological assays can take several days to weeks to provide information, the DiversiLab System holds promise for more rapid serotype classification for members of this group. [Copyright &y& Elsevier]

Campylobacter spp. are one of the leading bacterial etiologic agents of acute human gastroenteritis among industrialized countries. Poultry are implicated as a major source of the organism for human illness; however, the factors involved with colonization of poultry gastrointestinal systems remain unclear. Genomics and proteomics analyses were used to identify differences between poor- versus robust-colonizing Campylobacter jejuni isolates, 11168(GS) and A74/C, respectively. Sequence analyses of subtracted DNA resulted in A74/C-specifc genes similar to a dimethyl sulfoxide reductase, a serine protease, polysaccharide modification proteins, and restriction modification proteins. DNA microarray analyses were performed for comparison of A74/C to the complete genome sequences published for two C. jejuni. A total of 114 genes (7.1%) were determined absent from A74/C relative to those genomes. Additionally, proteomics was completed on both soluble and membrane protein extracts from 11168(GS) and A74/C. Variation in protein expression and physical characteristics such as p I was detected between the two isolates that included the major outer membrane protein, flagella, and aconitate hydratase. Several proteins including cysteine synthase and a Ni/Fe hydrogenase were determined to be differentially present between the two isolates. Finally, DNA hybridization analyses of 19 C. jejuni isolates recovered from chickens and humans worldwide over the past 20 years were performed to determine the distribution of a subset of differentially identified gene sequences. [ABSTRACT FROM AUTHOR]

Abstract: Plants are continually challenged by natural pathogens. Among a number of environmental factors, pre-harvest contamination of plants with pathogens responsible for enteric diseases in humans is of major international concern. Despite the knowledge of how bacterial attack can affect the biological system of plants, little is known about the effect of the interaction of these bacteria on plant’s metabolome. In order to investigate the metabolic change of Brassica induced by its response to different typically food borne bacteria such as Bacillus subtilis, Staphylococcus aureus, Escherichia coli, Salmonella typhimurium and Shigella flexneri, 1H NMR and two-dimensional NMR spectra, coupled with principal component analysis (PCA) and partial least square-discriminant analysis (PLS-DA) were applied to Brassica rapa which had been subjected to these pathogens during plant growth. The metabolic changes were found to vary according to bacterial species; for example, Gram-positive and Gram-negative bacteria had a different effect on the Brassica metabolome. While threonine and GABA were found to be the discriminating metabolites in Gram-positive bacteria treated plants, those treated with Gram-negative bacteria exhibited a significant increase in sinapoyl-malate, caffeoyl-malate and histidine. The detailed study of the effect of type of bacteria showed that amino acids, alcohols, carbohydrates and phenols were discriminating metabolites. These results prove the potential of NMR-based metabolomics as a tool to study the interaction of these food-borne bacteria with vegetables. [Copyright &y& Elsevier]

Abstract: Food poisoning originating from contaminated foods by both Gram-positive and Gram-negative bacteria causes concern to society and to the industry. Spices have been used safely since ancient times as food flavoring agents and also as herbal medicines and are now mainly considered “generally regarded as safe” (GRAS). Antimicrobial effects of two spices used in Iranian traditional medicine were investigated against some pathogenic food-borne bacteria. Hydroalcoholic extracts of Rhus coriaria L. (sumac) and Zataria multiflora Boiss. (avishan-e shirazi or zaatar) obtained from Tehran botanicals market were prepared by cool percolation method using 80% (v/v) aqueous alcohol. Antimicrobial activities of the extracts were tested against several Gram-positive and Gram-negative bacteria including Staphylococcus aureus, Bacillus cereus, Escherichia coli, Salmonella typhi, Proteus vulgaris, and Shigella flexneri. All the extracts were primarily screened for their possible antimicrobial effects using disc and well diffusion methods. Both R. coriaria L. and Z. multiflora Boiss. showed considerable antibacterial effects. The potential antibacterial activities of the two herbal extracts were further investigated at concentrations of 0.05%, 0.1%, 0.2%, 0.4%, 0.8% and 1.6% (w/v) and minimum inhibitory concentration (MICs) as well as minimum bactericidal concentrations (MBCs) of the extracts were elucidated. Sumac showed better activity against the tested bacteria compared to avishan-e shirazi inhibiting Bacillus cereus and Staphylococcus aureus at concentrations of 0.05% and 0.1%, respectively while Gram-negative bacteria were affected by higher concentrations of sumac ranging 0.1–2%. The MICs of avishan-e shirazi against the tested bacteria ranged from 0.4% to 0.8%. Salmonella typhi was found to be the most resistant showing the MICs of 0.2% and 0.8% with sumac and avishan-e shirazi, respectively. Both popular Iranian spices which are traditionally used as astringent agents have promising inhibitory effects on food-borne bacteria and could be considered as natural food preservatives. [Copyright &y& Elsevier]

Air constituency of the delicatessen sections of a retail group was assessed for the presence and distribution of bioaerosols and the correlation with physical parameters. Total viable counts were determined and the total coliforms, Escherichia coli, other members of the Enterobacteriaceae and Staphylococcus aureus were enumerated. These counts were relatively low, with the average total viable counts 1.34×102 cfu · m-3, Enterobacteriaceae 2.6×10 cfu · m-3 and S. aureus 2.2×10 cfu · m-3. Small numbers of total coliforms were detected and E. coli was not present at all. The distribution of Enterobacteriaceae differed significantly between three groups of visitor numbers and the total viable counts differed between two types of ventilation. The risk of infection should not be disregarded as a result of finding these organisms only in small numbers and could be a starting point in the prevention of food contamination, by regulating mechanisms to effectively minimize bioaerosols counts of enteric bacteria. [ABSTRACT FROM AUTHOR]

j. nguefack, b.b. budde and m. jakobsen. 2004.To investigate the antibacterial effect of five essential oils (EO) extracted from aromatic plants (Cymbopogon citratus,Ocimumbasilicum,Ocimum gratissimum,Thymus vulgarisandZingiber officinale) of Cameroon against strains ofListeria monocytogenes,L.innocuaandStaphylococcus aureus. The ability of selected EO to permeabilize the cytoplasmic membrane ofL. innocuawas also examined.The antibacterial activity of the EO determined by the agar diffusion method showed thatT. vulgarishad the highest activity followed byO. gratissimumandC. citratus. Lowest activity was recorded fromZ. officinaleandO. basilicum. Significant differences in sensitivity between strains ofListeriaandS.aureuswere observed. Flow cytometry ofL. innocuastained with carboxy-fluorescein diacetate showed that the fluorescence intensity of cells exposed to EO decreased faster than nonexposed cells, indicating that EO permeabilized the cytoplasmic membrane with the leakage of carboxy-fluorescein.Almost all the EO tested showed antibacterial activity to a different extent. The antibacterial effect was due to permeabilization of the cytoplasmic membrane.This study has identified the preservative potential of the EO examined. The use of sensitive method, such as flow cytometry, is advantageous for quick generation of data on the antibacterial effect of EO. [ABSTRACT FROM AUTHOR]

• Molecular and chemotaxonomic approaches are combined for plant authentication. • These approaches assist the morphological authentication of A. indica and A. argyi. • Six phytochemicals of the Artemisia species were identified. • Artemisia plants and their phytochemicals inhibit food-borne harmful bacteria. • This inhibition is via destruction of the bacterial membrane. Artemisia species are aromatic herbs used as food and/or ethnomedicine worldwide; however, the use of these plants is often impeded by misidentification. Here, molecular and chemotaxonomic approaches were combined to assist in the morphology-based authentication of Artemisia species, and Artemisia indica and Artemisia argyi were identified. The plant extracts and compounds obtained from these species, 1,8-cineole, carveol, α-elemene, α-farnesene, methyl linolenate, diisooctyl phthalate inhibited the growth of food-borne harmful bacteria. Mechanistic studies showed that the extract and active compounds of A. indica killed Gram-negative and -positive bacteria via destruction of the bacterial membrane. Finally, in vivo data demonstrated that A. indica protected against bacterial infection in mice as evidenced by survival rate, bacterial load in organs, gut pathology, diarrhea, body weight, food consumption, stool weight, and pathology score. A. indica and its active compounds have potential for use as food supplements for food-borne bacterial diseases and thus improve human health. [ABSTRACT FROM AUTHOR]

Blue light primarily exhibits antimicrobial activity through the activation of endogenous photosensitizers, which leads to the formation of reactive oxygen species that attack components of bacterial cells. Current data show that blue light is innocuous on the skin, but may inflict photo-damage to the eyes. Laboratory measurements indicate that antimicrobial blue light has minimal effects on the sensorial and nutritional properties of foods, although future research using human panels is required to ascertain these findings. Food properties also affect the efficacy of antimicrobial blue light, with attenuation or enhancement of the bactericidal activity observed in the presence of absorptive materials (for example, proteins on meats) or photosensitizers (for example, riboflavin in milk), respectively. Blue light can also be coupled with other treatments, such as polyphenols, essential oils and organic acids. While complete resistance to blue light has not been reported, isolated evidence suggests that bacterial tolerance to blue light may occur over time, especially through gene mutations, although at a slower rate than antibiotic resistance. Future studies can aim at characterizing the amount and type of intracellular photosensitizers across bacterial species and at assessing the oxygen-independent mechanism of blue light—for example, the inactivation of spoilage bacteria in vacuum-packed meats. [ABSTRACT FROM AUTHOR]