Biogenic amines(BAs),a class of toxic nitrogen-containing compounds,are commonly found in high-protein fermented foods.This study investigated whether,what and how the fermentation parameters influence the BAs accumul...Biogenic amines(BAs),a class of toxic nitrogen-containing compounds,are commonly found in high-protein fermented foods.This study investigated whether,what and how the fermentation parameters influence the BAs accumulation in spontaneous soy sauce fermentation.The results showed that BAs accumulation in soy sauce fermentation throughout the year showed significant seasonal differences,which were closely related to temperature and pH value.Furthermore,different microbial communities were found in high-and low-BAs groups,indicating that seasonal fermentation factors affect BAs accumulation by influencing the microbial population.Following bioinformatic analysis,single-microorganism culture analysis,and simulated fermentation,it was found that lower temperature or higher NaCl concentration can reduce BAs accumulation,most likely by suppressing the proliferation of BAs-producing bacteria.This is a comprehensive study of the impact of fermentation parameters on BAs production,and will serve as a foundation for future research on BAs management.展开更多
In order to improve the production of human-like collagen III(HLC III)by fed-batch culture of recombinant Escherichia coli BL21,the Plackett-Burman and Box-Behnken design were applied to optimize the fermentation proc...In order to improve the production of human-like collagen III(HLC III)by fed-batch culture of recombinant Escherichia coli BL21,the Plackett-Burman and Box-Behnken design were applied to optimize the fermentation process parameters.Three variables(induction time,inoculum age and pH),which have significant effects on HLC III production,were selected from eight variables by Plackett-Burman design.With the regression coefficient analysis in the Box-Behnken design,a relationship between HLC III production and three significant factors was obtained,and the optimum levels of the three variables were as follows:induction time 3.2h,inoculum age 12.6 h and pH 6.7.The 3D response surface plots and 2D contour plots created by the Box-Behnken design showed that the interaction between induction time and pH and that between innoculum age and pH were significant.An average 9.68 g·L1HLC III production was attained in the validation experiment under optimized condition,which was 80%higher than the yield of 5.36 g·L1before optimization.展开更多
Water kefir is a non-dairy fermented beverage produced by a microbial consortium primarily composed of lactic acid bacteria(LAB),acetic acid bacteria(AAB),and various yeasts.Despite the expanding literature on its pro...Water kefir is a non-dairy fermented beverage produced by a microbial consortium primarily composed of lactic acid bacteria(LAB),acetic acid bacteria(AAB),and various yeasts.Despite the expanding literature on its probiotic potential,microbial data remain fragmented due to methodological heterogeneity across studies.This study systematically reviewed and meta-analyzed 96 studies on water kefir fermentation to assess microbial load,community composition,and influencing variables.Prevalent microbial taxa were identified,and the effects of substrate type,temperature,and grain source on microbial dynamics were evaluated.The pooled microbial loads were 6.86 log CFU/mL for LAB,6.05 for AAB,6.16 for yeasts,and 7.37 for total aerobic bacteria.Lactobacillus was the most frequently reported genus(27.96%),followed by Lactococcus(9.23%),Acetobacter(9.13%),Gluconobacter(6.34%),Saccharomyces(5.03%),and Leuconostoc(4.29%).At the species level,Saccharomyces cerevisiae,Gluconobacter oxydans,and Lactobacillus casei were among the most commonly identified.Fermentation conditions centered around 25℃and an incubation duration of 48-72 h consistently supported enhanced microbial activity across all microbial groups(6.5-7.5 log CFU/mL).Household-sourced grains yielded slightly higher LAB and yeast counts than commercial ones.Compared to white sugar,brown sugar led to significantly higher LAB counts(p=0.049)and a near-significant increase in AAB(p=0.073).Among frequently used supplements(fig,coconut,and grape),fig was associated with the highest LAB abundance.Overall,this metaanalysis offers a consolidated view of water kefir’s microbial composition and diversity.It highlights key fermentation variables that shape microbial outcomes,providing practical guidance for improving the consistency and functional quality of water kefir.展开更多
基金This work was financially supported by National Key R&D Program of China(2018YFC1604100).
文摘Biogenic amines(BAs),a class of toxic nitrogen-containing compounds,are commonly found in high-protein fermented foods.This study investigated whether,what and how the fermentation parameters influence the BAs accumulation in spontaneous soy sauce fermentation.The results showed that BAs accumulation in soy sauce fermentation throughout the year showed significant seasonal differences,which were closely related to temperature and pH value.Furthermore,different microbial communities were found in high-and low-BAs groups,indicating that seasonal fermentation factors affect BAs accumulation by influencing the microbial population.Following bioinformatic analysis,single-microorganism culture analysis,and simulated fermentation,it was found that lower temperature or higher NaCl concentration can reduce BAs accumulation,most likely by suppressing the proliferation of BAs-producing bacteria.This is a comprehensive study of the impact of fermentation parameters on BAs production,and will serve as a foundation for future research on BAs management.
基金Supported by the National Natural Science Foundation of China（20776119） the National High Technology Research and Development Program of China（2007AA03Z456A） the Special Research Program of the Education Department of Shaanxi Province（07JK417）
文摘In order to improve the production of human-like collagen III(HLC III)by fed-batch culture of recombinant Escherichia coli BL21,the Plackett-Burman and Box-Behnken design were applied to optimize the fermentation process parameters.Three variables(induction time,inoculum age and pH),which have significant effects on HLC III production,were selected from eight variables by Plackett-Burman design.With the regression coefficient analysis in the Box-Behnken design,a relationship between HLC III production and three significant factors was obtained,and the optimum levels of the three variables were as follows:induction time 3.2h,inoculum age 12.6 h and pH 6.7.The 3D response surface plots and 2D contour plots created by the Box-Behnken design showed that the interaction between induction time and pH and that between innoculum age and pH were significant.An average 9.68 g·L1HLC III production was attained in the validation experiment under optimized condition,which was 80%higher than the yield of 5.36 g·L1before optimization.
文摘Water kefir is a non-dairy fermented beverage produced by a microbial consortium primarily composed of lactic acid bacteria(LAB),acetic acid bacteria(AAB),and various yeasts.Despite the expanding literature on its probiotic potential,microbial data remain fragmented due to methodological heterogeneity across studies.This study systematically reviewed and meta-analyzed 96 studies on water kefir fermentation to assess microbial load,community composition,and influencing variables.Prevalent microbial taxa were identified,and the effects of substrate type,temperature,and grain source on microbial dynamics were evaluated.The pooled microbial loads were 6.86 log CFU/mL for LAB,6.05 for AAB,6.16 for yeasts,and 7.37 for total aerobic bacteria.Lactobacillus was the most frequently reported genus(27.96%),followed by Lactococcus(9.23%),Acetobacter(9.13%),Gluconobacter(6.34%),Saccharomyces(5.03%),and Leuconostoc(4.29%).At the species level,Saccharomyces cerevisiae,Gluconobacter oxydans,and Lactobacillus casei were among the most commonly identified.Fermentation conditions centered around 25℃and an incubation duration of 48-72 h consistently supported enhanced microbial activity across all microbial groups(6.5-7.5 log CFU/mL).Household-sourced grains yielded slightly higher LAB and yeast counts than commercial ones.Compared to white sugar,brown sugar led to significantly higher LAB counts(p=0.049)and a near-significant increase in AAB(p=0.073).Among frequently used supplements(fig,coconut,and grape),fig was associated with the highest LAB abundance.Overall,this metaanalysis offers a consolidated view of water kefir’s microbial composition and diversity.It highlights key fermentation variables that shape microbial outcomes,providing practical guidance for improving the consistency and functional quality of water kefir.
