Study On The Diversity And Function Of Lactobacillus Buchneri In Brewing Baijiu System

The fermentation of traditional solid liquor is closely related to the dominant microorganisms in the liquor,and the flavor substances in the liquor are largely determined by the microorganisms it brews.Lactic acid bacteria play an important role in the brewing process of liquor,and its types and dynamic changes have an important influence on the quality and yield of liquor.It has been reported in recent years that Lactobacillus has the potential to metabolize n-propanol.Lactobacillus buchneri is a heterofermentative Lactobacillus bacteria whose genome contains three key enzymes that catalyze the production of n-propanol:propanediol dehydratase,1,3-propanediol dehydrogenase and1-propanol dehydrogenase.At present,L.brucei has more research and application on fermented feed,but there are few reports on the diversity and function of L.buchneri in liquor fermentation at home and abroad.L.buchneri is involved in the fermentation of thick sauce and fragrant liquor.Few studies have reported on the correlation and fermentation performance between buchneri and local indigenous yeasts.Based on the above problems,this topic has carried out the following aspects of research.Using the plate separation method,30 strains of Lactobacillus were isolated from different rounds of Baiyunbian winery.The 16S r DNA sequence analysis of the bacteria was carried out.The diversity of the Lactobacillus isolated in different rounds was compared and the different sources of L.buchneri.Tolerance differences between buchneri strains.The results showed that there were some differences in the types of Lactobacillus bacteria from different rounds of wine distillers.The 30 strains isolated were divided into 5genera and 3 genera by evolutionary tree analysis.The separation method has a certain relationship with the third and fourth rounds of entering and leaving the Chijiu environment.Comparing these 19 strains of L.buchneri isolated from different rounds of alcoholic acid resistance,the results show that:most L.buchneri medium cannot grow at p H 4.0;when the medium p H is below 4.5,growth will be significantly inhibited;The optimal p H value of L.buchneri is about 4.5.The acid resistance of L.buchneri strains from different rounds of wine has different differences:strains ZS-B3 and ZS-B9 can grow weakly at p H 4.0;strain ZS-B10 has the largest OD_{600 nm} value at p H 4.5,Reached 2.23.In terms of ethanol tolerance,there are significant differences between the L.buchneri strains isolated and screened in different rounds:strains ZS-B1,ZS-B2,ZS-B7,ZS-B10,ZS-B12,ZS-B13,ZS-B14 and ZS-B17 are more sensitive to ethanol,and the growth of 2%ethanol will inhibit its growth;while strains ZS-B6,ZS-B8,ZS-B9,ZS-B16,ZS-B18,ZS-B19,ZS-B20 and When the ethanol concentration of ZS-B21 in the medium is 6%,its OD_{600 nm}value can still reach more than 0.7;the strains ZS-B18 and ZS-B16 have the best ethanol tolerance,and the maximum ethanol concentration can reach 10%.In terms of temperature tolerance:L.buchneri grows vigorously at 37°C;strain growth is inhibited when the temperature is increased to 41°C;when the temperature is increased to 50°C,all strains do not grow.In addition,this study also screened a strain of Lactobacillus buchneri ZS-B16 with excellent tolerance from the liquor,and studied the role of this strain in the laboratory-scale solid-state fermentation of liquor.In this study,different combinations of L.buchneri,Lactobacillus plantarum,Saccharomyces cerevisiae,and Issatchenkia orientalis were used for liquid liquor fermentation experiments,and the fermentation products were analyzed by gas chromatography.The results showed that the single L.buchneri and L.plantarum strains did not produce n-propanol during pure liquid fermentation.The content of n-propanol produced by the L.buchneri and S.cerevisiae combination fermentation was significantly higher than that of the L.plantarum and S.cerevisiae combination.The former's n-propanol production was almost 1.36 times that of the latter.There is also a significant difference in n-propanol production between different yeast combinations of L.buchneri-S.Cerevisiae and L.buchneri-I.Orientalis.The former produces n-propanol 2.41 times the amount of the latter.This study compared the effects of Lactobacillus buchneri and the combination of Lactobacillus plantarum and Saccharomyces cerevisiae on the fermentation product of solid liquor.The results showed that the content of n-propanol produced by the combination of L.buchneri ZS-B16+SCY62+RP1 was 2.46 times that of the combination of L.plantarum ZR1+SCY62+RP1 and 4.89 times that of the combination of SCY62+RP1without Lactobacillus.4.89 times.The total acid,total ester and higher alcohol content of the fermented wine sample containing the combination of Lactobacillus brucelli were significantly higher than the latter two combinations.It shows that the presence of lactic acid bacteria can significantly increase the n-propanol content in the fermentation of liquor;the ability of L.buchneri and S.cerevisiae to solid state fermentation to produce n-propanol is significantly higher than the combination between L.plantarum and S.cerevisiae.There are also significant differences in the n-propanol content produced by fermentation of different Lactobacillus brucelli strains and Saccharomyces cerevisiae compositions.This study shows that Lactobacillus brevis may be associated with high levels of n-propanol and total acid and total ester production during the fermentation of liquor.