Pub Date : 2024-10-09DOI: 10.1016/j.fm.2024.104654
Bacillus subtilis produces proteases that hydrolyze proteins to produce bioactive peptides. Given the mounting waste from processed shrimp, the antimicrobial potential of peptides isolated from B. subtilis fermented shrimp waste was explored. Among the five peptides screened using molecular docking prediction, PVQ9 (AVFPSIVGRPR) had strong antibacterial activity against four common foodborne Gram-positive bacteria, i.e., Staphylococcus aureus, Bacillus cereus, Mammaliicoccus sciuri, and Kurthia gibsonii. The minimum bactericidal concentrations (MBCs) were 62.5 μg/mL for S. aureus and B. cereus, and 31.3 μg/mL for both M. sciuri and K. gibsonii, with a time-kill of 3 h observed for all strains. Mechanistically, it was demonstrated that PVQ9 could destroy bacterial cell walls, change bacteria cell membrane permeability, bind to bacteria DNA, and cause cell apoptosis. Most importantly, peptide PVQ9 could inhibit the spoilage of bean curd or tofu contaminated with K. gibsonii. These findings suggest that PVQ9 could be a useful preservative in controlling foodborne pathogenic bacteria in soy products and other processed foods.
{"title":"Bacillus subtilis fermented shrimp waste isolated peptide, PVQ9, and its antimicrobial mechanism on four Gram-positive foodborne bacteria","authors":"","doi":"10.1016/j.fm.2024.104654","DOIUrl":"10.1016/j.fm.2024.104654","url":null,"abstract":"<div><div><em>Bacillus subtilis</em> produces proteases that hydrolyze proteins to produce bioactive peptides. Given the mounting waste from processed shrimp, the antimicrobial potential of peptides isolated from <em>B. subtilis</em> fermented shrimp waste was explored. Among the five peptides screened using molecular docking prediction, PVQ9 (AVFPSIVGRPR) had strong antibacterial activity against four common foodborne Gram-positive bacteria, i.e., <em>Staphylococcus aureus</em>, <em>Bacillus cereus</em>, <em>Mammaliicoccus sciuri</em>, and <em>Kurthia gibsonii</em>. The minimum bactericidal concentrations (MBCs) were 62.5 μg/mL for <em>S. aureus</em> and <em>B. cereus</em>, and 31.3 μg/mL for both <em>M. sciuri</em> and <em>K. gibsonii</em>, with a time-kill of 3 h observed for all strains. Mechanistically, it was demonstrated that PVQ9 could destroy bacterial cell walls, change bacteria cell membrane permeability, bind to bacteria DNA, and cause cell apoptosis. Most importantly, peptide PVQ9 could inhibit the spoilage of bean curd or tofu contaminated with <em>K. gibsonii</em>. These findings suggest that PVQ9 could be a useful preservative in controlling foodborne pathogenic bacteria in soy products and other processed foods.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142420689","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-09DOI: 10.1016/j.fm.2024.104657
Acetobacter is one of the main species producing fruit vinegar and its tolerance mechanism to citric acid has not been fully studied. This limits fruit vinegar production from high-citric-acid fruits, which are excellent materials for fruit vinegar production. This study analyzed the metabolic differences between two strains of A. tropicalis with different citric acid tolerances using non-targeted metabolomics. Differential metabolites and metabolic pathways analysis showed that the enhanced amino acid metabolism significantly improved the citric acid tolerance of A. tropicalis and the deamination of amino acids may also play a role. In addition, the up-regulated phosphatidylcholine (PC) and N-heptanoylhonoserine lactone indicated decreased membrane permeability and enhanced quorum sensing (QS), respectively. The analysis of the interaction between pathways and metabolites indicated that Gln, Cys, and Tyr contribute to improving citric acid tolerance, which was also confirmed by the exogenous addition. After adding the amino acids, the down-regulated qdh, up-regulated ggt, and improved glutathione reductase (GR) activity in J-2736 indicated that glutathione metabolism played an important role in resisting citric acid, and cellular antioxidant capacity was increased. This study provides a theoretical basis for efficient fruit vinegar production from citric-acid-type fruits.
{"title":"Glutathione metabolism contributes to citric acid tolerance and antioxidant capacity in Acetobacter tropicalis","authors":"","doi":"10.1016/j.fm.2024.104657","DOIUrl":"10.1016/j.fm.2024.104657","url":null,"abstract":"<div><div><em>Acetobacter</em> is one of the main species producing fruit vinegar and its tolerance mechanism to citric acid has not been fully studied. This limits fruit vinegar production from high-citric-acid fruits, which are excellent materials for fruit vinegar production. This study analyzed the metabolic differences between two strains of <em>A</em>. <em>tropicalis</em> with different citric acid tolerances using non-targeted metabolomics. Differential metabolites and metabolic pathways analysis showed that the enhanced amino acid metabolism significantly improved the citric acid tolerance of <em>A. tropicalis</em> and the deamination of amino acids may also play a role. In addition, the up-regulated phosphatidylcholine (PC) and N-heptanoylhonoserine lactone indicated decreased membrane permeability and enhanced quorum sensing (QS), respectively. The analysis of the interaction between pathways and metabolites indicated that Gln, Cys, and Tyr contribute to improving citric acid tolerance, which was also confirmed by the exogenous addition. After adding the amino acids, the down-regulated <em>qdh</em>, up-regulated <em>ggt</em>, and improved glutathione reductase (GR) activity in J-2736 indicated that glutathione metabolism played an important role in resisting citric acid, and cellular antioxidant capacity was increased. This study provides a theoretical basis for efficient fruit vinegar production from citric-acid-type fruits.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142438467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-09DOI: 10.1016/j.fm.2024.104655
Lactic acid bacteria (LAB) are pivotal in constructing the intricate bio-catalytic networks underlying traditional fermented foods such as Baijiu. However, LAB and their metabolic mechanisms are partially understood in Moutai flavor Baijiu fermentation. Here, we found that Acetilactobacillus jinshanensis became the· dominant species with relative abundance reaching 92%, where the acid accumulated rapidly and peaked at almost 30 g/kg in Moutai flavor Baijiu. After separation, purification, and cultivation, A. jinshanensis exhibited pronounced acidophilia and higher acid resistance compared to other LAB. Further integrated multi-omics analysis revealed that fatty acid synthesis, cell membrane integrity, pHi and redox homeostasis maintenance, protein and amide syntheses were possibly crucial acid-resistant mechanisms in A. jinshanensis. Structural proteomics indicated that the surfaces of A. jinshanensis proteases contained more positively charged amino acid residues to maintain protein stability in acidic environments. The genes HSP20 and acpP were identified as acid-resistant genes for A. jinshanensis by heterologous expression analysis. These findings not only enhance our understanding of LAB in Baijiu, providing a scientific basis for acid regulation for production process, but also offer valuable insights for studying core species in other fermentation systems.
{"title":"Deciphering the acidophilia and acid resistance in Acetilactobacillus jinshanensis dominating baijiu fermentation through multi-omics analysis","authors":"","doi":"10.1016/j.fm.2024.104655","DOIUrl":"10.1016/j.fm.2024.104655","url":null,"abstract":"<div><div>Lactic acid bacteria (LAB) are pivotal in constructing the intricate bio-catalytic networks underlying traditional fermented foods such as <em>Baijiu</em>. However, LAB and their metabolic mechanisms are partially understood in <em>Moutai</em> flavor <em>Baijiu</em> fermentation. Here, we found that <em>Acetilactobacillus jinshanensis</em> became the· dominant species with relative abundance reaching 92%, where the acid accumulated rapidly and peaked at almost 30 g/kg in <em>Moutai</em> flavor <em>Baijiu</em>. After separation, purification, and cultivation, <em>A</em>. <em>jinshanensis</em> exhibited pronounced acidophilia and higher acid resistance compared to other LAB. Further integrated multi-omics analysis revealed that fatty acid synthesis, cell membrane integrity, pHi and redox homeostasis maintenance, protein and amide syntheses were possibly crucial acid-resistant mechanisms in <em>A. jinshanensis</em>. Structural proteomics indicated that the surfaces of <em>A. jinshanensis</em> proteases contained more positively charged amino acid residues to maintain protein stability in acidic environments. The genes <em>HSP20</em> and <em>acpP</em> were identified as acid-resistant genes for <em>A. jinshanensis</em> by heterologous expression analysis. These findings not only enhance our understanding of LAB in <em>Baijiu</em>, providing a scientific basis for acid regulation for production process, but also offer valuable insights for studying core species in other fermentation systems.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142438469","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-05DOI: 10.1016/j.fm.2024.104652
Listeria monocytogenes was the etiologic agent in nearly all recent outbreaks in North America attributed to pasteurized dairy products, whereas Escherichia coli O157 infections were responsible for most of the rare, yet serious complications from outbreaks involving unpasteurized dairy. This study determined the susceptibility of selected strains of L. monocytogenes and Shiga toxin-producing E. coli (STEC) to commercial phage preparations and their ability to control these pathogens in pasteurized and raw milk during 7-day storage at 7 °C. Both phage products demonstrated high lytic efficiency against 17 strains of L. monocytogenes whereas the efficiency of E. coli phages was more variable against 11 strains of O157 and non-O157 STEC. Broth microdilution assays identified effective endpoint multiplicities of infection (MOI) ranging from log 2.53 to 5.13, which differed between strains of L. monocytogenes and phage products. Mean log MOIs of E. coli phages against STEC also varied within and between products from 0.43 to 7.05. Despite these observations, the change in counts over time of three L. monocytogenes strains exposed to phage in pasteurized milk (log MOI 6) was similar with counts ∼ 4 log CFU/mL lower than control at day 7. Results for STEC O157 varied by strain but counts were lower than control in all cases by 72 h thorough day 7. Titers on isolates of both pathogens isolated from pasteurized milk indicated that the surviving populations were less susceptible to phage. The addition of a phage preparation to raw milk did not reduce populations of either pathogen or affect the change in counts of any strain over time when compared to control. Reduced efficacy in raw milk may be attributed to reduced phage binding as titers in raw milk decreased steadily (∼2 log PFU/mL) during storage. Commercial phage products may be a promising pathogen control intervention for pasteurized dairy products, warranting further investigation.
{"title":"Commercial bacteriophage preparations for the control of Listeria monocytogenes and Shiga toxin-producing Escherichia coli in raw and pasteurized milk","authors":"","doi":"10.1016/j.fm.2024.104652","DOIUrl":"10.1016/j.fm.2024.104652","url":null,"abstract":"<div><div><em>Listeria monocytogenes</em> was the etiologic agent in nearly all recent outbreaks in North America attributed to pasteurized dairy products, whereas <em>Escherichia coli</em> O157 infections were responsible for most of the rare, yet serious complications from outbreaks involving unpasteurized dairy. This study determined the susceptibility of selected strains of <em>L. monocytogenes</em> and Shiga toxin-producing <em>E. coli</em> (STEC) to commercial phage preparations and their ability to control these pathogens in pasteurized and raw milk during 7-day storage at 7 °C. Both phage products demonstrated high lytic efficiency against 17 strains of <em>L. monocytogenes</em> whereas the efficiency of <em>E. coli</em> phages was more variable against 11 strains of O157 and non-O157 STEC. Broth microdilution assays identified effective endpoint multiplicities of infection (MOI) ranging from log 2.53 to 5.13, which differed between strains of <em>L. monocytogenes</em> and phage products. Mean log MOIs of <em>E. coli</em> phages against STEC also varied within and between products from 0.43 to 7.05. Despite these observations, the change in counts over time of three <em>L. monocytogenes</em> strains exposed to phage in pasteurized milk (log MOI 6) was similar with counts ∼ 4 log CFU/mL lower than control at day 7. Results for STEC O157 varied by strain but counts were lower than control in all cases by 72 h thorough day 7. Titers on isolates of both pathogens isolated from pasteurized milk indicated that the surviving populations were less susceptible to phage. The addition of a phage preparation to raw milk did not reduce populations of either pathogen or affect the change in counts of any strain over time when compared to control. Reduced efficacy in raw milk may be attributed to reduced phage binding as titers in raw milk decreased steadily (∼2 log PFU/mL) during storage. Commercial phage products may be a promising pathogen control intervention for pasteurized dairy products, warranting further investigation.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142420688","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-05DOI: 10.1016/j.fm.2024.104649
Listeria monocytogenes is a foodborne pathogen of significant concern for the food industry due to its remarkable ability to persist through safety control efforts, posing a subsequent health threat to consumers. Understanding the microbial communities coexisting with L. monocytogenes in food processing environments provides insights into its persistence mechanisms. We investigated the microbial communities on non-food contact surfaces in a facility producing ready-to-eat foods, known to harbour a ST121 L. monocytogenes strain over multiple years. A 10-week sampling period was coordinated with the company and public health authorities. Metagenomic analysis revealed a stable microbial composition dominated by Pseudomonas fluorescens. While highly related populations were present in high-care production zones, distinctive taxa characteristic of specific areas were observed (e.g., Sphingomonas aerolata). Although Listeria spp. were not detected in metagenomes, they were detected in cultured samples, suggesting low relative abundance in factory settings. The findings suggest that a stable resident microbiota, with distinct adaptations to different areas within the factory, was selected for by their collective ability to survive control efforts in this environment. Listeria spp. was a member of this microbial community, albeit at low abundance, and may likewise benefit from the mutualism of the overall microbial community.
{"title":"Microbial composition and dynamics in environmental samples from a ready-to-eat food production facility with a long-term colonization of Listeria monocytogenes","authors":"","doi":"10.1016/j.fm.2024.104649","DOIUrl":"10.1016/j.fm.2024.104649","url":null,"abstract":"<div><div><em>Listeria monocytogenes</em> is a foodborne pathogen of significant concern for the food industry due to its remarkable ability to persist through safety control efforts, posing a subsequent health threat to consumers. Understanding the microbial communities coexisting with <em>L. monocytogenes</em> in food processing environments provides insights into its persistence mechanisms. We investigated the microbial communities on non-food contact surfaces in a facility producing ready-to-eat foods, known to harbour a ST121 <em>L. monocytogenes</em> strain over multiple years. A 10-week sampling period was coordinated with the company and public health authorities. Metagenomic analysis revealed a stable microbial composition dominated by <em>Pseudomonas fluorescens</em>. While highly related populations were present in high-care production zones, distinctive taxa characteristic of specific areas were observed (e.g., <em>Sphingomonas aerolata</em>). Although <em>Listeria</em> spp. were not detected in metagenomes, they were detected in cultured samples, suggesting low relative abundance in factory settings. The findings suggest that a stable resident microbiota, with distinct adaptations to different areas within the factory, was selected for by their collective ability to survive control efforts in this environment. <em>Listeria</em> spp. was a member of this microbial community, albeit at low abundance, and may likewise benefit from the mutualism of the overall microbial community.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142421329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-04DOI: 10.1016/j.fm.2024.104653
Highly pathogenic avian influenza (HPAI) clade 2.3.4.4b H5Nx viruses continue to cause episodic incursions and have been detected in more than 12 taxonomic orders encompassing more than 80 avian species, terrestrial and marine mammals, including lactating dairy cows. HPAI H5N1 spillover to dairy cattle creates a new interface for human exposure and raises food safety concerns. The presence of H5N1 genetic material in one out of five retail pasteurized milk samples in the USA has prompted the evaluation of the pasteurization processes for the inactivation of influenza viruses. Our study examined whether pasteurization could effectively inactivate HPAI H5N1 spiked into raw whole milk. First, we heated 1 mL of non-homogenized cow milk samples to attain an internal temperature of 63°C or 72°C and spiked with 6.3 log10 EID50 of clade 2.3.4.4b H5N1 virus. Complete inactivation was achieved after incubation of the H5N1 spiked raw milk at 63°C for 30 min. In addition, viral inactivation was observed in seven of eight experimental replicates when treated at 72°C for 15s. In one of the replicates, a 4.44 log10 virus reduction was achieved, which is about 1 log higher than the average viral quantities detected in bulk milk in affected areas. Therefore, we conclude that pasteurization of milk is an effective strategy for mitigation of the risk of human exposure to milk contaminated with H5N1 virus.
{"title":"Effectiveness of pasteurization for the inactivation of H5N1 influenza virus in raw whole milk","authors":"","doi":"10.1016/j.fm.2024.104653","DOIUrl":"10.1016/j.fm.2024.104653","url":null,"abstract":"<div><div>Highly pathogenic avian influenza (HPAI) clade 2.3.4.4b H5Nx viruses continue to cause episodic incursions and have been detected in more than 12 taxonomic orders encompassing more than 80 avian species, terrestrial and marine mammals, including lactating dairy cows. HPAI H5N1 spillover to dairy cattle creates a new interface for human exposure and raises food safety concerns. The presence of H5N1 genetic material in one out of five retail pasteurized milk samples in the USA has prompted the evaluation of the pasteurization processes for the inactivation of influenza viruses. Our study examined whether pasteurization could effectively inactivate HPAI H5N1 spiked into raw whole milk. First, we heated 1 mL of non-homogenized cow milk samples to attain an internal temperature of 63°C or 72°C and spiked with 6.3 log<sub>10</sub> EID<sub>50</sub> of clade 2.3.4.4b H5N1 virus. Complete inactivation was achieved after incubation of the H5N1 spiked raw milk at 63°C for 30 min. In addition, viral inactivation was observed in seven of eight experimental replicates when treated at 72°C for 15s. In one of the replicates, a 4.44 log<sub>10</sub> virus reduction was achieved, which is about 1 log higher than the average viral quantities detected in bulk milk in affected areas. Therefore, we conclude that pasteurization of milk is an effective strategy for mitigation of the risk of human exposure to milk contaminated with H5N1 virus.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142420686","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-10-02DOI: 10.1016/j.fm.2024.104651
To unlock the potential of strains for further enhancing the aromatic complexity of kiwifruit wines while avoiding undesirable flavors, indigenous non-Saccharomyces yeast extracellular extract treatment for fermentation was established. The extracellular extract from Zygosaccharomyces rouxii, Pichia kudriavzevii, and Meyerozyma guilliermondii were prepared and supplemented individually or in pairs to the kiwifruit wine fermentation system. Subsequently, the changes in physicochemical properties, antioxidants, and volatile characteristics of kiwifruit wines produced by different protocols were comprehensively evaluated, and the major aroma descriptors affecting sensory acceptability were analyzed by sensory evaluation and partial least squares regression. The results showed that extracellular extract treatment significantly improved the organic acids and monomeric phenols content, antioxidant capacity, and volatiles of kiwifruit wines. Compared to Sc, the increase in esters and alcohols, along with the decrease in aldehydes and acids in Pk-Zr and Mg-Zr, enhanced the aromatic complexity while reduce grassy and fungal flavors, resulting in higher sensory acceptability.
{"title":"Enhancing nutritional composition and aroma characteristics of kiwifruit wines through indigenous non-Saccharomyces yeast extracellular extract treatment","authors":"","doi":"10.1016/j.fm.2024.104651","DOIUrl":"10.1016/j.fm.2024.104651","url":null,"abstract":"<div><div>To unlock the potential of strains for further enhancing the aromatic complexity of kiwifruit wines while avoiding undesirable flavors, indigenous non-<em>Saccharomyces</em> yeast extracellular extract treatment for fermentation was established. The extracellular extract from <em>Zygosaccharomyces rouxii</em>, <em>Pichia kudriavzevii</em>, and <em>Meyerozyma guilliermondii</em> were prepared and supplemented individually or in pairs to the kiwifruit wine fermentation system. Subsequently, the changes in physicochemical properties, antioxidants, and volatile characteristics of kiwifruit wines produced by different protocols were comprehensively evaluated, and the major aroma descriptors affecting sensory acceptability were analyzed by sensory evaluation and partial least squares regression. The results showed that extracellular extract treatment significantly improved the organic acids and monomeric phenols content, antioxidant capacity, and volatiles of kiwifruit wines. Compared to Sc, the increase in esters and alcohols, along with the decrease in aldehydes and acids in Pk-Zr and Mg-Zr, enhanced the aromatic complexity while reduce grassy and fungal flavors, resulting in higher sensory acceptability.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142420685","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-29DOI: 10.1016/j.fm.2024.104650
This study compares the plate count (PC) and the Propidium Monoazide-quantitative Polymerase Chain Reaction (PMA-qPCR) methods to assess the growth of a cocktail of three serotypes of Salmonella enterica (Heidelberg, Typhimurium, and Enteritidis) in cooked, sliced, and vacuum-packaged turkey breast (STB) under isothermal storage temperatures (8 °C–20 °C), using predictive models. Standard curves were developed for PMA-qPCR, demonstrating high efficiency (101%) and sensitivity, with quantification limits ranging from 1 to 2 log10 CFU/g for all temperatures studied. Comparative analysis revealed a significant correlation (R2 = 0.99; 95% CI) between the PC and PMA-qPCR methods; however, the agreement analysis indicated a mean difference (Bias) of −0.11 log10 CFU/g (p < 0.05), suggesting underestimation by the PC method. This indicates the presence of stressed or viable but nonculturable (VBNC) cells, detectable by PMA-qPCR but not by PC. The Baranyi and Roberts model showed a good ability to describe the behavior of S. enterica cocktail in STB for PC and PMA-qPCR data under all isothermal conditions. The exponential secondary model more accurately represented the temperature dependence of the maximum specific growth rate compared to the Ratkowsky square root model, with R2 values ≥ 0.984 and RMSE values ≤ 0.011 for both methods. These results suggest that combining PMA-qPCR with predictive modeling allows for a more accurate prediction of S. enterica growth, compared to PC method. In the event of cold chain disruptions of meat products, the use of PMA-qPCR method allow the quantification of VBNC cells, that can still pose a health risk to consumers, especially in ready-to-eat products.
{"title":"Propidium monoazide (PMA) qPCR assay compared to the plate count method for quantifying the growth of Salmonella enterica serotypes in vacuum-packaged turkey breast combined with a mathematical modeling approach","authors":"","doi":"10.1016/j.fm.2024.104650","DOIUrl":"10.1016/j.fm.2024.104650","url":null,"abstract":"<div><div>This study compares the plate count (PC) and the Propidium Monoazide-quantitative Polymerase Chain Reaction (PMA-qPCR) methods to assess the growth of a cocktail of three serotypes of <em>Salmonella enterica</em> (Heidelberg, Typhimurium, and Enteritidis) in cooked, sliced, and vacuum-packaged turkey breast (STB) under isothermal storage temperatures (8 °C–20 °C), using predictive models. Standard curves were developed for PMA-qPCR, demonstrating high efficiency (101%) and sensitivity, with quantification limits ranging from 1 to 2 log<sub>10</sub> CFU/g for all temperatures studied. Comparative analysis revealed a significant correlation (<em>R</em><sup><em>2</em></sup> = 0.99; 95% CI) between the PC and PMA-qPCR methods; however, the agreement analysis indicated a mean difference (Bias) of −0.11 log<sub>10</sub> CFU/g (<em>p</em> < 0.05), suggesting underestimation by the PC method. This indicates the presence of stressed or viable but nonculturable (VBNC) cells, detectable by PMA-qPCR but not by PC. The Baranyi and Roberts model showed a good ability to describe the behavior of <em>S</em>. <em>enterica</em> cocktail in STB for PC and PMA-qPCR data under all isothermal conditions. The exponential secondary model more accurately represented the temperature dependence of the maximum specific growth rate compared to the Ratkowsky square root model, with <em>R</em><sup><em>2</em></sup> values ≥ 0.984 and <em>RMSE</em> values ≤ 0.011 for both methods. These results suggest that combining PMA-qPCR with predictive modeling allows for a more accurate prediction of <em>S</em>. <em>enterica</em> growth, compared to PC method. In the event of cold chain disruptions of meat products, the use of PMA-qPCR method allow the quantification of VBNC cells, that can still pose a health risk to consumers, especially in ready-to-eat products.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142359646","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-09-27DOI: 10.1016/j.fm.2024.104646
Strong-flavor Baijiu (SFB) production has relied on pit mud (PM) as a starter culture. The maturation time of natural PM (NPM) is about 30 years, so artificial PM (APM) with a shorter maturation time has attracted widespread attention. This study reveals the microbial and functional dissimilarities of APM and NPM, and helps to elucidate the different metabolic roles of microbes during substrate degradation and flavor formation. Significant differences in the microbial community were observed between APM and NPM, manifesting as variations in the abundance of core microorganisms. Total of 187 high-quality metagenome-assembled genomes (MAGs) were obtained based on the metagenomic binning technology, mainly including Firmicutes (n = 106), Bacteroidota (n = 15) and Chloroflexota (n = 14). Furthermore, the relative concentration of flavor compounds in 4-year APM was similar to those in 30-year NPM, but different from those in 100-year NPMs. Methanosarcina, Methanobacterium, Methanoculleus, Anaerolineae bacterium and Aminobacterium were the key bacteria responsible for the flavor differences. From a functional perspective, amino acid and carbohydrate metabolism were key functions of PM microbial, and showed differences between APM and NPM. Finally, substrate degradation and flavor generation pathways were found to exist in multiple microorganisms. Combine the relative abundance of microorganisms with the absolute abundance of enzymes, Clostridium, Lactobacillus, Petrimonas, Methanoculleus, Prevotella, Methanobacterium, Methanosarcina, Methanothrix, Proteiniphilum, Bellilinea, Anaerolinea, Anaeromassilibacillus, Syntrophomonas and Brevefilum were identified as the key microorganisms in APM and NPM.
{"title":"Metagenomics-based insights into the microbial community dynamics and flavor development potentiality of artificial and natural pit mud","authors":"","doi":"10.1016/j.fm.2024.104646","DOIUrl":"10.1016/j.fm.2024.104646","url":null,"abstract":"<div><div>Strong-flavor Baijiu (SFB) production has relied on pit mud (PM) as a starter culture. The maturation time of natural PM (NPM) is about 30 years, so artificial PM (APM) with a shorter maturation time has attracted widespread attention. This study reveals the microbial and functional dissimilarities of APM and NPM, and helps to elucidate the different metabolic roles of microbes during substrate degradation and flavor formation. Significant differences in the microbial community were observed between APM and NPM, manifesting as variations in the abundance of core microorganisms. Total of 187 high-quality metagenome-assembled genomes (MAGs) were obtained based on the metagenomic binning technology, mainly including Firmicutes (n = 106), Bacteroidota (n = 15) and Chloroflexota (n = 14). Furthermore, the relative concentration of flavor compounds in 4-year APM was similar to those in 30-year NPM, but different from those in 100-year NPMs. <em>Methanosarcina</em>, <em>Methanobacterium</em>, <em>Methanoculleus</em>, Anaerolineae bacterium and <em>Aminobacterium</em> were the key bacteria responsible for the flavor differences. From a functional perspective, amino acid and carbohydrate metabolism were key functions of PM microbial, and showed differences between APM and NPM. Finally, substrate degradation and flavor generation pathways were found to exist in multiple microorganisms. Combine the relative abundance of microorganisms with the absolute abundance of enzymes, <em>Clostridium</em>, <em>Lactobacillus</em>, <em>Petrimonas</em>, <em>Methanoculleus</em>, <em>Prevotella</em>, <em>Methanobacterium</em>, <em>Methanosarcina</em>, <em>Methanothrix</em>, <em>Proteiniphilum</em>, <em>Bellilinea</em>, <em>Anaerolinea</em>, <em>Anaeromassilibacillus</em>, <em>Syntrophomonas</em> and <em>Brevefilum</em> were identified as the key microorganisms in APM and NPM.</div></div>","PeriodicalId":12399,"journal":{"name":"Food microbiology","volume":null,"pages":null},"PeriodicalIF":4.5,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142359645","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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