Cross protection can undermine the effectiveness of control measures on foodborne pathogens,and therefore brings major implications for food safety.In this work,the capacity of Salmonella Enteritidis to mount ethanol ...Cross protection can undermine the effectiveness of control measures on foodborne pathogens,and therefore brings major implications for food safety.In this work,the capacity of Salmonella Enteritidis to mount ethanol tolerance following acid adaptation was characterized by analysis of cell viability and cell membrane property.It was observed that preadaptation to pH 4.5 significantly(P<0.05)increased the tolerance of log-phase cells to ethanol;in contrast,stationary-phase cells displayed reduced ethanol tolerance after acid adaptation.However,acid adaptation did not cause cell leakage and morphological change in both log-phase and stationary-phase S.Enteritidis.Fatty acid analysis further revealed that the amount of C_(14:0),C_(17:0 cyclo) and C_(19:0 cyclo) fatty acids was increased,while that of C_(16:1ω7c) and C_(18:1ω7c) fatty acids was decreased,respectively,in response to acid adaptation,regardless of bacterial growth phase.Notably,acid adaptation significantly(P<0.05)increased the proportion of C_(16:0) fatty acid in log-phase cells,but this effect did not occur in stationary-phase cells.Moreover,exogenous addition of C_(16:0) fatty acid to stationary-phase acid-adapted cultures was able to enhance bacterial ethanol tolerance.Taken together,C_(16:0) fatty acid is involved in the growth-phase-dependent protective effect of acid adaptation on ethanol tolerance in S.Enteritidis.展开更多
Objectives:Salmonella spp.is a world-leading foodborne pathogen and its rapid detection is essential for ensuring food safety.Conventional methods require expensive instruments,considerable operational skills and cann...Objectives:Salmonella spp.is a world-leading foodborne pathogen and its rapid detection is essential for ensuring food safety.Conventional methods require expensive instruments,considerable operational skills and cannot provide fast mobile on-site systems to detect Salmonella in food.Materials and Methods:A visual method was established based on multiple recombinase polymerase amplification(RPA)coupled with lateral flow dipsticks(LFD)for the simultaneous detection of Salmonella spp.,Salmonella Enteritidis and Salmonella Typhimurium in vitro and food.Results:The optimal volume and temperature for the multiplex RPA-LFD method were determined to be 25μL and 38°C,respectively.The reaction process was completed within 25 min and the results were observed visually.The limits of detection(LODs)were 2.8×10^(2),5.9×10^(2),and 7.6×10^(2) CFU/mL for Salmonella spp.,S.Enteritidis and S.Typhimurium,respectively.Meanwhile,the results of the established method showed no cross-reactivity between the Salmonella cells and other common foodborne bacteria,which was highly specific for Salmonella.More importantly,the developed method exhibited good performance in artificially contaminated chicken samples with the LODs of 2.8×10^(3),5.9×10^(3),and 7.6×10^(3) CFU/mL for Salmonella spp.,S.Enteritidis,and S.Typhimurium,respectively.Finally,the application of the multiple RPA-LFD methods in retailed food samples displayed that this method was effective and practical for the detection of Salmonella spp.in food.Conclusion:The developed multiplex RPA-LFD method provides a new sensitive and rapid alternative for the specific detection of Salmonella spp.and its important serovars in food.展开更多
Stability assessme nt of observed tolerance phe no types is integral in un dersta nding stress adaptati on in food-borne pathogens.Therefore,the current work was carried out to determine whether ethanol adaptation ind...Stability assessme nt of observed tolerance phe no types is integral in un dersta nding stress adaptati on in food-borne pathogens.Therefore,the current work was carried out to determine whether ethanol adaptation induced by exposure to 5 percent ethanol for 60 min is a stable phenomenon in Salmonella enterica serovar Enteritidis.The capacity of Salmonella Enteritidis(S.Enteritidis)to maintain the acquired ethanol adaptation in the absenee of sublethal ethanol stress was investigated at 37℃,25℃ or 4℃ in Luria-Bertani broth and two types of meat juice.It was found that ethanol adaptation was completely reversed within 40 min at 37℃ or within 60 min at 25℃,but was stable at 4℃ for at least 48 h in the broth assay.Ethanol adaptation was retained in chicken juice during 60-min incubation at 25℃ or 48h incubation at 4℃.Moreover,exposure to pork juice stored at either 25℃ or 4℃ sigrdficantly(P<0.05)increased the ethanol toleranee of ethanol-adapted cells.Collectively,these fin dings suggest that ethanol adaptation stability in S.En teritidis under cold conditi ons and in meat juices should be take n into acco unt whe n con ducting a comprehensive risk analysis during food processing.展开更多
基金supported by the National Key Research and Development Program of China(2019YFE0119700)the National Natural Science Foundation of China(32001797)+1 种基金the Science and Technology Innovation Agricultural Project of Shanghai Science and Technology Commission(19391902100)the Natural Science Foundation of Shanghai(22ZR1429900).
文摘Cross protection can undermine the effectiveness of control measures on foodborne pathogens,and therefore brings major implications for food safety.In this work,the capacity of Salmonella Enteritidis to mount ethanol tolerance following acid adaptation was characterized by analysis of cell viability and cell membrane property.It was observed that preadaptation to pH 4.5 significantly(P<0.05)increased the tolerance of log-phase cells to ethanol;in contrast,stationary-phase cells displayed reduced ethanol tolerance after acid adaptation.However,acid adaptation did not cause cell leakage and morphological change in both log-phase and stationary-phase S.Enteritidis.Fatty acid analysis further revealed that the amount of C_(14:0),C_(17:0 cyclo) and C_(19:0 cyclo) fatty acids was increased,while that of C_(16:1ω7c) and C_(18:1ω7c) fatty acids was decreased,respectively,in response to acid adaptation,regardless of bacterial growth phase.Notably,acid adaptation significantly(P<0.05)increased the proportion of C_(16:0) fatty acid in log-phase cells,but this effect did not occur in stationary-phase cells.Moreover,exogenous addition of C_(16:0) fatty acid to stationary-phase acid-adapted cultures was able to enhance bacterial ethanol tolerance.Taken together,C_(16:0) fatty acid is involved in the growth-phase-dependent protective effect of acid adaptation on ethanol tolerance in S.Enteritidis.
基金supported by the National Key R&D Program of China(No.2019YFE0119700)the National Natural Science Foundation of China(No.32172316).
文摘Objectives:Salmonella spp.is a world-leading foodborne pathogen and its rapid detection is essential for ensuring food safety.Conventional methods require expensive instruments,considerable operational skills and cannot provide fast mobile on-site systems to detect Salmonella in food.Materials and Methods:A visual method was established based on multiple recombinase polymerase amplification(RPA)coupled with lateral flow dipsticks(LFD)for the simultaneous detection of Salmonella spp.,Salmonella Enteritidis and Salmonella Typhimurium in vitro and food.Results:The optimal volume and temperature for the multiplex RPA-LFD method were determined to be 25μL and 38°C,respectively.The reaction process was completed within 25 min and the results were observed visually.The limits of detection(LODs)were 2.8×10^(2),5.9×10^(2),and 7.6×10^(2) CFU/mL for Salmonella spp.,S.Enteritidis and S.Typhimurium,respectively.Meanwhile,the results of the established method showed no cross-reactivity between the Salmonella cells and other common foodborne bacteria,which was highly specific for Salmonella.More importantly,the developed method exhibited good performance in artificially contaminated chicken samples with the LODs of 2.8×10^(3),5.9×10^(3),and 7.6×10^(3) CFU/mL for Salmonella spp.,S.Enteritidis,and S.Typhimurium,respectively.Finally,the application of the multiple RPA-LFD methods in retailed food samples displayed that this method was effective and practical for the detection of Salmonella spp.in food.Conclusion:The developed multiplex RPA-LFD method provides a new sensitive and rapid alternative for the specific detection of Salmonella spp.and its important serovars in food.
基金supported by the National Key Research and Development Program of China(No.2019YFE0119700)the National Natural Science Foundation of China(No.32001797)the China Postdoctoral Science Foundation(No.2019M661516).
文摘Stability assessme nt of observed tolerance phe no types is integral in un dersta nding stress adaptati on in food-borne pathogens.Therefore,the current work was carried out to determine whether ethanol adaptation induced by exposure to 5 percent ethanol for 60 min is a stable phenomenon in Salmonella enterica serovar Enteritidis.The capacity of Salmonella Enteritidis(S.Enteritidis)to maintain the acquired ethanol adaptation in the absenee of sublethal ethanol stress was investigated at 37℃,25℃ or 4℃ in Luria-Bertani broth and two types of meat juice.It was found that ethanol adaptation was completely reversed within 40 min at 37℃ or within 60 min at 25℃,but was stable at 4℃ for at least 48 h in the broth assay.Ethanol adaptation was retained in chicken juice during 60-min incubation at 25℃ or 48h incubation at 4℃.Moreover,exposure to pork juice stored at either 25℃ or 4℃ sigrdficantly(P<0.05)increased the ethanol toleranee of ethanol-adapted cells.Collectively,these fin dings suggest that ethanol adaptation stability in S.En teritidis under cold conditi ons and in meat juices should be take n into acco unt whe n con ducting a comprehensive risk analysis during food processing.
