The long fermentation period constitutes a crucial process for enhancing the quality of base liquor in the production of Chinese strong-flavor Baijiu.In the present study,a comprehensive metaproteomic analysis of ferm...The long fermentation period constitutes a crucial process for enhancing the quality of base liquor in the production of Chinese strong-flavor Baijiu.In the present study,a comprehensive metaproteomic analysis of fermented grains in the long fermentation period led to the identification of 44 plant proteins and 1460 microbial proteins.Following 12 days of fermentation,bacterial proteins exhibited a rapid surge,constituting the predominant components of fermented grains proteins,ranging from 64.64 to 81.28%.The differential proteins were predominantly associated with carbohydrate metabolism,energy metabolism,and amino acid metabolism.Among these,days 18 to 220 were dominated by differential protein in the protein hydrolase system and amino acid metabolic of the bacteria.Pathway analysis delineated the potential metabolic pathways through which cysteine,tyrosine,proline,isoleucine,among others,could be metabolized to yield pyruvic acid,acetyl-CoA,ultimately leading to the production of acetic acid,butyric acid,and hexanoic acid.Furthermore,phenylalanine underwent metabolism,resulting in the production of phenylacetaldehyde,phenylacetic acid,and phenylacetic acid ethyl ester.With the extension of fermentation time,lactic acid underwent conversion to pyruvic acid,contributing to the generation of other acids,while aldehydes were converted to alcohols and acids.展开更多
The intense flavor compounds in baijiu give it a unique taste and umami.This study used metagenomics,ma-chine learning,experimental validation,and molecular docking to identify three candidate umami peptides:EFFSNYGTR...The intense flavor compounds in baijiu give it a unique taste and umami.This study used metagenomics,ma-chine learning,experimental validation,and molecular docking to identify three candidate umami peptides:EFFSNYGTRV,EFFSNYDTRL,and GCWGRGRLCQW,from fermented grains(jiupei).Sensory evaluation showed that these peptides enhance umami with a threshold range of 0.09-0.116 mmol/L,and EFFSNYDTRL exhibited the best umami properties.Molecular docking and molecular dynamics simulations revealed that T1R1/T1R3 and the three candidate peptides can form stable complexes,with hydrogen bonding and hydrophobic in-teractions playing essential roles.The study also identified Glu,Tyr,and Ser as the critical residues to which the three candidate peptides bind in the umami receptor T1R1/T1R3.Our study demonstrates the potential of machine learning approaches to mine umami peptides from metagenomics data that can accelerate the devel-opment and in-depth study of umami peptides.展开更多
A new procedure of determining optimal C/N (the rate of carbon source to nitrogen source) of mixed distillers' grains for combined bacteria synergic fermentation is established. At the same time an improved method...A new procedure of determining optimal C/N (the rate of carbon source to nitrogen source) of mixed distillers' grains for combined bacteria synergic fermentation is established. At the same time an improved method evaluating bacteria growth, called method of dry cell weighing by filtering is developed. For each combination of C and N, their initial and residual contents before and after fermentation respectively are determined. Then followed the calculation of utilization of C and N sources by the compound bacteria. The optimal C/N is finally located from among the utilization of C and N of several combinations and the weight of produced mass of oven dried thallus. The conditions of fermentation are: inoculum size 10%, temperature 30 0℃, rotational speed 170 r/min, shake culture time 48h. The best results obtained from orthogonal experiments are: maximum mass of oven dried thallus is 14 693g in a liter liquid medium, maximum utilization rate of carbon source is 98 13% and maximum utilization rate of nitrogen is 78 14%. Optimal C/N is 5 1.展开更多
The fermentation of sauce-flavor Baijiu requires high-temperature Daqu as the starter,which is classified into three types:white,yellow,and black.Recent studies highlighted the variability of the microbiota and metab-...The fermentation of sauce-flavor Baijiu requires high-temperature Daqu as the starter,which is classified into three types:white,yellow,and black.Recent studies highlighted the variability of the microbiota and metab-olome profiles of these three types of Daqu,however,what functions they precisely provide in the sauce-flavor Baijiu brewing process remains unclear.In this study,white,yellow,and black Daqu in five different proportions were utilized as starters in field-scale Baijiu fermentation,with the control group lacking Daqu inoculation.Fermented grains inoculated with 100%white Daqu(47.7℃)had the highest temperature during stacking fermentation,while 100%black Daqu and control groups were lower than 45℃.Lactic acid(12.6-22.0 mg/g)was the most abundant organic acid,followed by acetic acid(0.7-5.0 mg/g).qPCR analysis revealed that bac-terial biomass decreased during fermentation,while fungal biomass increased.A comparison with the control revealed that Daqu contributed high-temperature resistant microorganisms to the stacking fermentation process,primarily Kroppenstedtia,Virgibacillus,Byssochlamys,Thermoascus,and Thermomyces.Meanwhile,stacking fermentation promoted the enrichment of Acetobacter,Kazachstania,and Leiothecium.Mantel test and co-occurrence network analysis revealed that utilizing different fermentation starters could vary the biotic and abiotic factors that drive microbial community succession.We investigated the flavor of Baijiu further,and found that fermentation with white Daqu enhanced the accumulation of ethyl acetate,isoamyl alcohol,and isobutanol,whereas black Daqu increased the accumulation of ethyl lactate,lactic acid,and furfural.This study contributes to the rational usage of different types of Daqu in the manufacturing of Baijiu.展开更多
The microbial community and product flavor of fermented foods are subject to seasonal environmental fluctuations due to open production environment.However,research on the impact of external environmental changes caus...The microbial community and product flavor of fermented foods are subject to seasonal environmental fluctuations due to open production environment.However,research on the impact of external environmental changes caused by seasonal shifts on brewing is limited.Here,we studied changes in physicochemical indicators and flavor compounds of fermented grains during Baijiu fermentation in four seasons,as well as the succession and assembly of microbial communities.The temperature throughout fermentation was highest in summer,followed by spring and autumn,and lowest in winter.Winter had slower rates of moisture growth,total acidity accumulation,and sugar consumption than the other seasons.At the end of fermentation,the highest total organic acid content was identified in summer,and the lowest level of volatile compounds was found in winter.We found significant differences in microbial community structure across different seasons.Meanwhile,compared to fungal community,the succession of bacterial community was more susceptible to brewing environment,with reducing sugar being the main driving factor in the early stage and total acidity,organic acids,and moisture being the main driving factors in the late stage.The microbial co-occurrence networks in autumn and winter were more complex than those in spring and summer.Furthermore,brewing in the spring and summer promoted the accumulation of acids in Baijiu,esters in summer,ethyl esters in autumn,and aldehydes and ketones in winter.This study offers a fresh perspective on the microbial brewing mechanism of Baijiu by exploring the seasonal variations of microbiota and metabolome.展开更多
Lactic acid(LA)is a significant byproduct in Baijiu fermentation,with both isomers of LA and ethyl lactate(EL)being present in strong-aroma Baijiu.D(-)-isomers cannot be metabolized by humans,and their excessive accum...Lactic acid(LA)is a significant byproduct in Baijiu fermentation,with both isomers of LA and ethyl lactate(EL)being present in strong-aroma Baijiu.D(-)-isomers cannot be metabolized by humans,and their excessive accumulation can be harmful.This study aims to enhance the proportion of the beneficial L(+)-isomer in Baijiu.We analyzed 106 commercially available strong-aroma Baijiu samples,along with fermented grains(Zaopei),yellow water(Huangshui),and Baijiu samples from 10 Baijiu factories,confirming the coexistence of D(-)-LA and L(+)-LA in fermentation products.Notably,a strong correlation was found between L(+)-LA in Zaopei and L(+)-EL in Baijiu.Microbial community analysis revealed that Lactobacillus and Bacillus were the dominant bac-terial groups,with a succession of microbial communities throughout fermentation.We isolated two strains from Zaopei with high selectivity for L(+)-LA production:Bacillus licheniformis(A6)and Bacillus cereus(B12).Incor-porating these strains into both liquid-and solid-state fermentation systems markedly increased the proportion of L(+)-EL relative to total ethyl lactate in Baijiu.This study successfully isolated and applied L(+)-LA-producing strains to fermentation models,offering a practical strategy for increasing L(+)-LA content in Baijiu.展开更多
基金financially supported by the National Natural Science Foundation of China(22138004)National Treasure Ecological Research Synergetic Innovation Center.
文摘The long fermentation period constitutes a crucial process for enhancing the quality of base liquor in the production of Chinese strong-flavor Baijiu.In the present study,a comprehensive metaproteomic analysis of fermented grains in the long fermentation period led to the identification of 44 plant proteins and 1460 microbial proteins.Following 12 days of fermentation,bacterial proteins exhibited a rapid surge,constituting the predominant components of fermented grains proteins,ranging from 64.64 to 81.28%.The differential proteins were predominantly associated with carbohydrate metabolism,energy metabolism,and amino acid metabolism.Among these,days 18 to 220 were dominated by differential protein in the protein hydrolase system and amino acid metabolic of the bacteria.Pathway analysis delineated the potential metabolic pathways through which cysteine,tyrosine,proline,isoleucine,among others,could be metabolized to yield pyruvic acid,acetyl-CoA,ultimately leading to the production of acetic acid,butyric acid,and hexanoic acid.Furthermore,phenylalanine underwent metabolism,resulting in the production of phenylacetaldehyde,phenylacetic acid,and phenylacetic acid ethyl ester.With the extension of fermentation time,lactic acid underwent conversion to pyruvic acid,contributing to the generation of other acids,while aldehydes were converted to alcohols and acids.
基金the National Natural Science Foundation of China,China(Grant No.32072770)for providing financial support.
文摘The intense flavor compounds in baijiu give it a unique taste and umami.This study used metagenomics,ma-chine learning,experimental validation,and molecular docking to identify three candidate umami peptides:EFFSNYGTRV,EFFSNYDTRL,and GCWGRGRLCQW,from fermented grains(jiupei).Sensory evaluation showed that these peptides enhance umami with a threshold range of 0.09-0.116 mmol/L,and EFFSNYDTRL exhibited the best umami properties.Molecular docking and molecular dynamics simulations revealed that T1R1/T1R3 and the three candidate peptides can form stable complexes,with hydrogen bonding and hydrophobic in-teractions playing essential roles.The study also identified Glu,Tyr,and Ser as the critical residues to which the three candidate peptides bind in the umami receptor T1R1/T1R3.Our study demonstrates the potential of machine learning approaches to mine umami peptides from metagenomics data that can accelerate the devel-opment and in-depth study of umami peptides.
文摘A new procedure of determining optimal C/N (the rate of carbon source to nitrogen source) of mixed distillers' grains for combined bacteria synergic fermentation is established. At the same time an improved method evaluating bacteria growth, called method of dry cell weighing by filtering is developed. For each combination of C and N, their initial and residual contents before and after fermentation respectively are determined. Then followed the calculation of utilization of C and N sources by the compound bacteria. The optimal C/N is finally located from among the utilization of C and N of several combinations and the weight of produced mass of oven dried thallus. The conditions of fermentation are: inoculum size 10%, temperature 30 0℃, rotational speed 170 r/min, shake culture time 48h. The best results obtained from orthogonal experiments are: maximum mass of oven dried thallus is 14 693g in a liter liquid medium, maximum utilization rate of carbon source is 98 13% and maximum utilization rate of nitrogen is 78 14%. Optimal C/N is 5 1.
基金supported by the Research Foundation for Scientific Scholars of Moutai Institute(mygccrc[2022]012).
文摘The fermentation of sauce-flavor Baijiu requires high-temperature Daqu as the starter,which is classified into three types:white,yellow,and black.Recent studies highlighted the variability of the microbiota and metab-olome profiles of these three types of Daqu,however,what functions they precisely provide in the sauce-flavor Baijiu brewing process remains unclear.In this study,white,yellow,and black Daqu in five different proportions were utilized as starters in field-scale Baijiu fermentation,with the control group lacking Daqu inoculation.Fermented grains inoculated with 100%white Daqu(47.7℃)had the highest temperature during stacking fermentation,while 100%black Daqu and control groups were lower than 45℃.Lactic acid(12.6-22.0 mg/g)was the most abundant organic acid,followed by acetic acid(0.7-5.0 mg/g).qPCR analysis revealed that bac-terial biomass decreased during fermentation,while fungal biomass increased.A comparison with the control revealed that Daqu contributed high-temperature resistant microorganisms to the stacking fermentation process,primarily Kroppenstedtia,Virgibacillus,Byssochlamys,Thermoascus,and Thermomyces.Meanwhile,stacking fermentation promoted the enrichment of Acetobacter,Kazachstania,and Leiothecium.Mantel test and co-occurrence network analysis revealed that utilizing different fermentation starters could vary the biotic and abiotic factors that drive microbial community succession.We investigated the flavor of Baijiu further,and found that fermentation with white Daqu enhanced the accumulation of ethyl acetate,isoamyl alcohol,and isobutanol,whereas black Daqu increased the accumulation of ethyl lactate,lactic acid,and furfural.This study contributes to the rational usage of different types of Daqu in the manufacturing of Baijiu.
基金supported by the National Natural Science Foundation of China[grant number 32370142]the China Postdoctoral Science Foundation[grant numbers 2024T170375 and 2023M741512].
文摘The microbial community and product flavor of fermented foods are subject to seasonal environmental fluctuations due to open production environment.However,research on the impact of external environmental changes caused by seasonal shifts on brewing is limited.Here,we studied changes in physicochemical indicators and flavor compounds of fermented grains during Baijiu fermentation in four seasons,as well as the succession and assembly of microbial communities.The temperature throughout fermentation was highest in summer,followed by spring and autumn,and lowest in winter.Winter had slower rates of moisture growth,total acidity accumulation,and sugar consumption than the other seasons.At the end of fermentation,the highest total organic acid content was identified in summer,and the lowest level of volatile compounds was found in winter.We found significant differences in microbial community structure across different seasons.Meanwhile,compared to fungal community,the succession of bacterial community was more susceptible to brewing environment,with reducing sugar being the main driving factor in the early stage and total acidity,organic acids,and moisture being the main driving factors in the late stage.The microbial co-occurrence networks in autumn and winter were more complex than those in spring and summer.Furthermore,brewing in the spring and summer promoted the accumulation of acids in Baijiu,esters in summer,ethyl esters in autumn,and aldehydes and ketones in winter.This study offers a fresh perspective on the microbial brewing mechanism of Baijiu by exploring the seasonal variations of microbiota and metabolome.
基金supported by the Open Fund Project of Liquor Making Biotechnology and Application of Key Laboratory of Sichuan Province(funding number NJ2022-07,awarded to Zhiqiang Ren).
文摘Lactic acid(LA)is a significant byproduct in Baijiu fermentation,with both isomers of LA and ethyl lactate(EL)being present in strong-aroma Baijiu.D(-)-isomers cannot be metabolized by humans,and their excessive accumulation can be harmful.This study aims to enhance the proportion of the beneficial L(+)-isomer in Baijiu.We analyzed 106 commercially available strong-aroma Baijiu samples,along with fermented grains(Zaopei),yellow water(Huangshui),and Baijiu samples from 10 Baijiu factories,confirming the coexistence of D(-)-LA and L(+)-LA in fermentation products.Notably,a strong correlation was found between L(+)-LA in Zaopei and L(+)-EL in Baijiu.Microbial community analysis revealed that Lactobacillus and Bacillus were the dominant bac-terial groups,with a succession of microbial communities throughout fermentation.We isolated two strains from Zaopei with high selectivity for L(+)-LA production:Bacillus licheniformis(A6)and Bacillus cereus(B12).Incor-porating these strains into both liquid-and solid-state fermentation systems markedly increased the proportion of L(+)-EL relative to total ethyl lactate in Baijiu.This study successfully isolated and applied L(+)-LA-producing strains to fermentation models,offering a practical strategy for increasing L(+)-LA content in Baijiu.
