Correlation between microbial diversity and flavor metabolism in Huangshui: A by-product of solid-state fermentation Baijiu

Huangshui (HS), a by-product of solid-state fermentation Baijiu, is being given more attention on comprehensive utilization because of its abundant microbial and nutritional resources. To effectively utilize HS for improving the economic benefits, correlations between microbial community and flavor compounds in different HS samples were uncovered in the present study. Lactobacillus, Methanobacterium, Methanobrevibacter, Methanoculleus, and Methanosarcina were dominant genera in all the samples. Additionally, Caproiciproducens and Clostridium were positively related with Methanosaeta, while Lactobacillus exhibited a negative relationship with occurrence of Methanobacterium, Methanoplasma, and Methanolobus. Linear discriminant analysis effect size (LEfSe) showed that 33 flavor compounds mainly including caproic acid, butyric acid, acetic acid, and ethyl caproate, were significantly different between the samples, and these compounds were positively correlated with Ruminococcaceae, Bacteroides, and methanogenic archaea by redundancy analysis (RDA). Furthermore, abundant genes encoding enzymes participated in glycolysis pathway and carboxylic acid chain elongation process which involved in formation of caproic acid and butyric acid were observed by Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt2). These results provided scientific basis of microbiota and their flavor metabolism in HS, and laid theoretical foundation for rational and effective utilization of microbial functions in HS.