Fermented chile pepper mash is a major food product in New Mexico. There are few reports on the fermentation process or on methods to monitor it, In the current study we examined a pour plate procedure with an overlay...Fermented chile pepper mash is a major food product in New Mexico. There are few reports on the fermentation process or on methods to monitor it, In the current study we examined a pour plate procedure with an overlay using plate count agar and 3 MTM PetrifilmTM Aerobic Count （AC） plates for determination of total aerobic bacterial counts during the fermentation of chile mash. Fifty chile mash samples were obtained directly from commercial fermentation vats and examined within 2 h of collection. Serial dilutions of the chile mash were prepared in Butterfield＇s Phosphate Buffer. 1 mL portions of the diluted samples were aliquoted in duplicate onto the AC plates and into empty Petri dishes. Plate count agar was poured and once the plates had solidified, they were overlaid with about 10 mL of PCA to minimize spreaders. Plates were incubated at 30 ℃ for 48 h and enumerated. Paired difference tests were conducted on log transformed data to compare the results of the two plating procedures. For commercial chile mash samples, we did not show any significant differences between the AC plate counts and the pour plate counts （α = 0.05）, 3 MTM PetrifilmTM AC plates are a good alternative to pour plates for the determination of the total aerobic counts in fermented chile mashes.展开更多
[Objectives]To determine the aerobic plate count(APC)in the milk samples,evaluate the uncertainty of the test results,and to provide a scientific basis for the quality control of the testing process.[Methods]In compli...[Objectives]To determine the aerobic plate count(APC)in the milk samples,evaluate the uncertainty of the test results,and to provide a scientific basis for the quality control of the testing process.[Methods]In compliance with the national food safety standard Food Microbiological Examination:Aerobic Plate Count(GB 4789.2-2016),the aerobic plate count in the milk samples was detected.The source of the uncertainty of the test result was analyzed and a mathematical model was established in accordance with Evaluation and Expression of Uncertainty in Measurement(JJF 1059.1-2012).Then,the introduced uncertainty components were evaluated to determine the uncertainty of the final combined aerobic plate count.[Results]The expanded uncertainty of the test result of the aerobic plate count in the milk samples was 0.0434,and the logarithmic value interval of the results was(3.924,4.010),and the antilogarithm was taken to get the aerobic plate count in the sample to be 8395-10233 CFU/mL.[Conclusions]This method can effectively evaluate the uncertainty of the aerobic plate count,and ensure the accurate and scientific laboratory test data.展开更多
[Objectives]This study was conducted to investigate the main factors affecting the aerobial plate count in raw milk.[Methods]Drinking water,medicated baths and raw milk under different storage and transportation condi...[Objectives]This study was conducted to investigate the main factors affecting the aerobial plate count in raw milk.[Methods]Drinking water,medicated baths and raw milk under different storage and transportation conditions were detected for the values of aerobial plate count to analyze their effects on the aerobial plate count in raw milk.[Results]Disinfection of drinking water tanks could significantly reduce the aerobial plate count in water.The use of medicated baths before and after milking could effectively reduce the aerobial plate count and had a significant bactericidal effect.The growth of microorganisms in raw milk stored below 4℃was relatively slow.Regularly disinfecting drinking water tanks and disinfecting nipples before and after milking could reduce the aerobial plate count in the tanks and nipples.After raw milk was extruded,the temperature should decrease to 0-4℃within 2 h,and the storage time should not exceed 48 h,which could effectively control the aerobial plate count in raw milk.[Conclusions]This study provides a reference for scientific control of the aerobial plate count in raw milk.展开更多
目的建立炭疽芽孢杆菌的微滴式数字聚合酶链式反应(Droplet digital PCR,ddPCR)方法对炭疽芽孢杆菌实验室活动污染的定量评估提供技术支持。方法以炭疽芽孢杆菌pXO1质粒编码保护性抗原pagA基因为靶序列,优化微滴数字PCR方法的反应条件,...目的建立炭疽芽孢杆菌的微滴式数字聚合酶链式反应(Droplet digital PCR,ddPCR)方法对炭疽芽孢杆菌实验室活动污染的定量评估提供技术支持。方法以炭疽芽孢杆菌pXO1质粒编码保护性抗原pagA基因为靶序列,优化微滴数字PCR方法的反应条件,建立实验室微环境中炭疽芽孢杆菌核酸定量方法;对比微滴式数字PCR方法和平板计数法的定量评估效果,分析ddPCR的灵敏性、特异性和重复性。结果建立的ddPCR方法最佳引物和探针终浓度分别为900nmol·L^(-1)和250nmol·L^(-1),最佳退火温度为60℃,最佳升降温速度为1℃/s,本方法的最低检测下限为1.12copies·μL^(-1),未发现与常见疫病存在交叉反应,重复性试验的变异系数小于5%。结论本研究中建立的炭疽芽孢杆菌的微滴数字PCR方法敏感性高、特异性强、重复性好,为疫情监测、流行病学调查和实验室污染微环境检测提供重要技术。展开更多
The effects of disinfectants and plasmid-based antibiotic resistance genes(ARGs)on the growth of microorganisms and the plasmid-mediated transfer of ARGs in the water and biofilm of the drinkingwater distribution syst...The effects of disinfectants and plasmid-based antibiotic resistance genes(ARGs)on the growth of microorganisms and the plasmid-mediated transfer of ARGs in the water and biofilm of the drinkingwater distribution system under simulated conditionswere explored.The heterotrophic plate count of the water in reactors with 0.1 mg/L NaClO and NH_(2)Cl was higher than in the control groups.Therewas no similar phenomenon in biofilm.In thewater of reactors containing NaClO,the aphA and bla geneswere lower than in the antibiotic resistant bacteria group,while both genes were higher in the water of reactors with NH_(2)Cl than in the control group.Chloramine may promote the transfer of ARGs in the water phase.Both genes in the biofilm of the reactors containing chlorine were lower than the control group.Correlation analysis between ARGs and water quality parameters revealed that the copy numbers of the aphA gene were significantly positively correlated with the copy numbers of the bla gene in water and significantly negatively correlated in biofilm(p<0.05).The results of the sequencing assay showed that bacteria in the biofilm,in the presence of disinfectant,were primarily Gram-negative.1.0 mg/L chlorine decreased the diversity of the community in the biofilm.The relative abundance of some bacteria that may undergo transfer increased in the biofilm of the reactor containing 0.1 mg/L chlorine.展开更多
建立一种能排除高浓度乳酸菌本底干扰的发酵用乳酸菌菌粉中污染菌总数的检测方法。实验采用不同计数琼脂培养基和不同检验方法测定6种乳酸菌质控样和4种市售发酵用乳酸菌菌粉中乳酸菌的生长情况,确定最优检测用培养基和检验方法,并以4...建立一种能排除高浓度乳酸菌本底干扰的发酵用乳酸菌菌粉中污染菌总数的检测方法。实验采用不同计数琼脂培养基和不同检验方法测定6种乳酸菌质控样和4种市售发酵用乳酸菌菌粉中乳酸菌的生长情况,确定最优检测用培养基和检验方法,并以4种人工污染的乳酸菌菌粉为试样进行方法有效性验证。结果表明:乳酸菌菌粉稀释样经微孔滤膜抽滤法和砂芯漏斗过滤处理后,结合不含糖的无碳源菌落计数琼脂(plate count medium without carbon source,PCCS)培养,可在有效抑制菌粉中乳酸菌生长的同时对污染菌进行特异性计数,检测下限低至10CFU/g。该方法具有良好的检测灵敏度,可用于发酵用乳酸菌菌粉中污染菌的快速、准确计数,有效提高菌粉生产过程及终产品的质量管控。展开更多
文摘Fermented chile pepper mash is a major food product in New Mexico. There are few reports on the fermentation process or on methods to monitor it, In the current study we examined a pour plate procedure with an overlay using plate count agar and 3 MTM PetrifilmTM Aerobic Count （AC） plates for determination of total aerobic bacterial counts during the fermentation of chile mash. Fifty chile mash samples were obtained directly from commercial fermentation vats and examined within 2 h of collection. Serial dilutions of the chile mash were prepared in Butterfield＇s Phosphate Buffer. 1 mL portions of the diluted samples were aliquoted in duplicate onto the AC plates and into empty Petri dishes. Plate count agar was poured and once the plates had solidified, they were overlaid with about 10 mL of PCA to minimize spreaders. Plates were incubated at 30 ℃ for 48 h and enumerated. Paired difference tests were conducted on log transformed data to compare the results of the two plating procedures. For commercial chile mash samples, we did not show any significant differences between the AC plate counts and the pour plate counts （α = 0.05）, 3 MTM PetrifilmTM AC plates are a good alternative to pour plates for the determination of the total aerobic counts in fermented chile mashes.
基金National Key R&D Program for the Thirteenth Five-Year Plan Period(2017YFE0110800).
文摘[Objectives]To determine the aerobic plate count(APC)in the milk samples,evaluate the uncertainty of the test results,and to provide a scientific basis for the quality control of the testing process.[Methods]In compliance with the national food safety standard Food Microbiological Examination:Aerobic Plate Count(GB 4789.2-2016),the aerobic plate count in the milk samples was detected.The source of the uncertainty of the test result was analyzed and a mathematical model was established in accordance with Evaluation and Expression of Uncertainty in Measurement(JJF 1059.1-2012).Then,the introduced uncertainty components were evaluated to determine the uncertainty of the final combined aerobic plate count.[Results]The expanded uncertainty of the test result of the aerobic plate count in the milk samples was 0.0434,and the logarithmic value interval of the results was(3.924,4.010),and the antilogarithm was taken to get the aerobic plate count in the sample to be 8395-10233 CFU/mL.[Conclusions]This method can effectively evaluate the uncertainty of the aerobic plate count,and ensure the accurate and scientific laboratory test data.
基金Supported by Hebei Province Phase III Modern Agricultural Industry Technology System Cow Innovation Team Building ProjectThe Fourth Batch of High-end Talent Project in Hebei ProvinceHebei Provincial Science and Technology Innovation Leading Talents(21130243A).
文摘[Objectives]This study was conducted to investigate the main factors affecting the aerobial plate count in raw milk.[Methods]Drinking water,medicated baths and raw milk under different storage and transportation conditions were detected for the values of aerobial plate count to analyze their effects on the aerobial plate count in raw milk.[Results]Disinfection of drinking water tanks could significantly reduce the aerobial plate count in water.The use of medicated baths before and after milking could effectively reduce the aerobial plate count and had a significant bactericidal effect.The growth of microorganisms in raw milk stored below 4℃was relatively slow.Regularly disinfecting drinking water tanks and disinfecting nipples before and after milking could reduce the aerobial plate count in the tanks and nipples.After raw milk was extruded,the temperature should decrease to 0-4℃within 2 h,and the storage time should not exceed 48 h,which could effectively control the aerobial plate count in raw milk.[Conclusions]This study provides a reference for scientific control of the aerobial plate count in raw milk.
文摘目的建立炭疽芽孢杆菌的微滴式数字聚合酶链式反应(Droplet digital PCR,ddPCR)方法对炭疽芽孢杆菌实验室活动污染的定量评估提供技术支持。方法以炭疽芽孢杆菌pXO1质粒编码保护性抗原pagA基因为靶序列,优化微滴数字PCR方法的反应条件,建立实验室微环境中炭疽芽孢杆菌核酸定量方法;对比微滴式数字PCR方法和平板计数法的定量评估效果,分析ddPCR的灵敏性、特异性和重复性。结果建立的ddPCR方法最佳引物和探针终浓度分别为900nmol·L^(-1)和250nmol·L^(-1),最佳退火温度为60℃,最佳升降温速度为1℃/s,本方法的最低检测下限为1.12copies·μL^(-1),未发现与常见疫病存在交叉反应,重复性试验的变异系数小于5%。结论本研究中建立的炭疽芽孢杆菌的微滴数字PCR方法敏感性高、特异性强、重复性好,为疫情监测、流行病学调查和实验室污染微环境检测提供重要技术。
基金supported by the Natural Science Foundation of China(No.52070145,51778453).
文摘The effects of disinfectants and plasmid-based antibiotic resistance genes(ARGs)on the growth of microorganisms and the plasmid-mediated transfer of ARGs in the water and biofilm of the drinkingwater distribution system under simulated conditionswere explored.The heterotrophic plate count of the water in reactors with 0.1 mg/L NaClO and NH_(2)Cl was higher than in the control groups.Therewas no similar phenomenon in biofilm.In thewater of reactors containing NaClO,the aphA and bla geneswere lower than in the antibiotic resistant bacteria group,while both genes were higher in the water of reactors with NH_(2)Cl than in the control group.Chloramine may promote the transfer of ARGs in the water phase.Both genes in the biofilm of the reactors containing chlorine were lower than the control group.Correlation analysis between ARGs and water quality parameters revealed that the copy numbers of the aphA gene were significantly positively correlated with the copy numbers of the bla gene in water and significantly negatively correlated in biofilm(p<0.05).The results of the sequencing assay showed that bacteria in the biofilm,in the presence of disinfectant,were primarily Gram-negative.1.0 mg/L chlorine decreased the diversity of the community in the biofilm.The relative abundance of some bacteria that may undergo transfer increased in the biofilm of the reactor containing 0.1 mg/L chlorine.
文摘建立一种能排除高浓度乳酸菌本底干扰的发酵用乳酸菌菌粉中污染菌总数的检测方法。实验采用不同计数琼脂培养基和不同检验方法测定6种乳酸菌质控样和4种市售发酵用乳酸菌菌粉中乳酸菌的生长情况,确定最优检测用培养基和检验方法,并以4种人工污染的乳酸菌菌粉为试样进行方法有效性验证。结果表明:乳酸菌菌粉稀释样经微孔滤膜抽滤法和砂芯漏斗过滤处理后,结合不含糖的无碳源菌落计数琼脂(plate count medium without carbon source,PCCS)培养,可在有效抑制菌粉中乳酸菌生长的同时对污染菌进行特异性计数,检测下限低至10CFU/g。该方法具有良好的检测灵敏度,可用于发酵用乳酸菌菌粉中污染菌的快速、准确计数,有效提高菌粉生产过程及终产品的质量管控。
