Zooming in on Butyrate-Producing Clostridial Consortia in the Fermented Grains of Gene Sequence-Guided Microbial Isolation.

Butyrate, one of the key aroma compounds in Luzhou-flavor , is synthesized through two alternative pathways: butyrate kinase () and butyryl-CoA: acetate CoA-transferase (). A lack of knowledge of butyrate-producing microorganisms hinders our ability to understand the flavor formation mechanism of . Here, temporal dynamics of microbial metabolic profiling in fermented grains (FG) was explored PICRUSt based on 16S rRNA gene sequences. We found Bacilli and Bacteroidia were the major potential butyrate producers in pathway at the beginning of fermentation, while later Clostridia dominated the two pathways. Clone library analysis also revealed that Clostridia (~73% OTUs) was predominant in pathway throughout fermentation, followed by Bacilli and Bacteroidia, and pathway was merely possessed by Clostridia. Afterward, Clostridia-specific 16S rRNA gene sequencing demonstrated might be the major butyrate-producing genus in two pathways, which was subsequently evaluated using culture approach. Seventeen species were isolated from FG based on 16S rRNA gene sequence-guided medium prediction method. Profiles of short-chain fatty acids and and genes in these species demonstrated phylogenetic and functional diversities of butyrate-producing in FG. These findings add to illustrate the diversity of potential butyrate producers during brewing and provide a workflow for targeting functional microbes in complex microbial community.