Wheat-origin Bacillus community drives the formation of characteristic metabolic profile in high-temperature Daqu

Abstract

The wheat-origin microbiota plays a crucial role in the microbiome assembly of high-temperature Daqu (HTD), particularly during the early incubation stage. In this study, we compared the succession of microbiota and accumulation of metabolites in two groups: one with inactivated wheat-origin microbiotas and the other with non-inactivated microbiotas, under simulated incubation conditions. The results showed that the wheat-origin Bacillus improved the microbial diversity and metabolite profiles by regulating sugar and amino acid metabolisms. Furthermore, four Bacillus strains with excellent fermentation capabilities were specifically isolated and screened from wheat. Bioaugmentation test on HTD further validated that these wheat-origin Bacillus strains enhanced the accumulation of functional enzymes during the early incubation stage. Amylase activity in HTD significantly increased after inoculation with Priestia megaterium, while protease activity saw a significant boost after Bacillus aerophilus inoculation. Additionally, the introduction of wheat-origin Bacillus strains into the HTD microbiome exogenously caused structural changes in the microbial community, heightened the metabolic activity of the microbiota, and led to elevated levels of amino acids and sugars. The collective findings underscore the pivotal role of the wheat-origin Bacillus community in shaping the distinctive metabolic profile of high-temperature Daqu.