| Strong-Flavor liquor is distilled liquor obtained by distilling the ferment in the cellar built from pit mud,and the pit mud is mainly to provide a stable and suitable environment for the growth and reproduction of microorganisms and metabolic processes.These microorganisms in the pit mud play an irreplaceable role in the quality of baijiu,so the pit mud is considered to be the most influential factor in the quality of wine.Lactic acid bacteria,one of the important bacterial groups in the pit mud,is one of the indispensable microorganisms in the brewing process of Chinese liquor.However,if the content of lactic acid bacteria is excessive,the quality of the wine will be reduced.However,the role and changes in content of lactic acid bacteria cause changes in the quality of the pit mud and the interaction between them and other microorganisms are still unknown.The confusing effect of lactic acid bacteria in the pit mud has a great impact on the liquor brewing process,so the in-depth study of the role of lactic acid bacteria and the microbial community in different types of strong-scent liquor mud is of great significance for improving the quality of Strong-Flavor liquor and the maintenance of the pit mud in the liquor industry.According to the diversity index table,phylum level classification,genus level classification,principal co-ordinates analysis and genus heat map analysis of the microbial community in the four pit mud samples,the relative content of Firmicutes phylum is higher in different pit mud samples,its relative content tends to decrease with increasing pit mud age;the relative content of Lactobacillus genus is higher in samples of pit mud with low cellar age,and its relative content decreases with increasing cellar age,while the content in the degraded pit mud reaches 90%;through the principal co-ordinates analysis and cluster analysis of the heat map,samples of same pit ages can be well gathered together,indicating a certain correlation between the microbial community in the pit mud and the age of the pit mud.With the increase of cellar age,the diversity of the microbial community in the pit mud gradually increased,and the microbial community gradually showed a stable trend.Through the analysis of the difference and change trend of the content of lactic acid bacteria in four kinds of pit mud,the number of species of lactic acid bacteria(LAB)in pit mud of different Strong-Flavor liquor has a certain relationship with the geographical location,this difference may be caused by the environment factors;among the four pit mud samples of different Strong-Flavor liquor,the content of Lactobacillus is the highest,and its order of magnitude is much larger than that of other lactic acid bacteria.The relative content of some lactic acid bacteria decreases with the increase of cellar age and Some increase;in the analysis of the types and contents of the Lactobacillus OTU(Operational Taxonomic Unit,operable taxonomic unit)in the pit mud,the OTU486 in the Gujinggong pit mud only exists in the pit mud of the NC group,identified and classified as s?unclassified?g?Lactobacillus respectively;in Jiannanchun pit mud samples,the relative content trend of OTU1244 and OTU135 increased with the increase of pit age,These Lactobacillus OTUs were identified and classified as s?unclassified?k?norank?d?Bacteria and s?Lactobacillus?acidipiscis respectively;and in Tanggouliangxianghe,OTU812 and OTU862 in pit mud samples were not detected in pit mud of group N,but the content in group H was very high,showing a trend of increasing with the quality of pit mud,both of which are classified as s?Lactobacillus?acetotolerans;OTU428,OTU434 and OTU492 in the samples of Luzhou Laojiao only existed in the 40-year-old pit mud group.These Lactobacillus OTU were identified and classified as s?unclassified?g?Lactobacillus,s?Lactobacillus?farciminis and s?unclassified?g?Lactobacillus.These special Lactobacillus OTUs can be identified in the same type of strong-flavor liquor pit mud.Using the existing information in the PICRUSt(Phylogenetic Investigation of Communities by Reconstruction of Unobserved States)and Kyoto Encyclopedia of Genes and Genomes(KEGG)databases,the functions in the mud of four different types of strong-flavor liquor,the differences in gene abundance were analyzed.Among the four different types of strong-flavor liquor pit mud,the abundance of KEGG Orthology and Pathway Level 3 abundance were relatively uniform in the old pit mud,while those has poor repeatability in the short pit age group samples;in the analysis of Clusters of Orthologous Groups(COG),there are a large number of Clusters of Orthologous Groups with unknown functions,and B / A / Z / W of which respectively represent the Chromatin structure and dynamics,RNA processing and modification,Cytoskeleton and Extracellular structures,their abundance in four different strong-flavor liquor pit mud is quite different.Through the analysis of key enzyme genes in the process of hexanoic acid synthesis,methanogenesis and lactic acid production,it was found that the key enzyme genes related to lactic acid synthesis are higher in the new cellar group,while that the key enzyme genes of hexanoic acid synthesis and methanogenesis were higher abundance in the high-quality pit mud are more beneficial to this phenomenon,which is conducive to the process of "increasing hexanoic acid and reducing lactic acid " in the brewing industry of strong-flavor liquor.In the analysis of the bacterium interaction network of pit mud,the interactions in samples with short pit age are more likely to gather together,and most of the bacteria are positively correlated,and the strength of their interaction(the correlation coefficient ? absolute Value)are also different from each other,and as the age of the pit mud increases,the negative correlation between the genera also increases,forming a "helping each other" trend,the positive and negative correlations between the microbial genera are alternating with each other. |
PDF Full Text Request