Identification of the saccharifying microbiota based on the absolute quantitative analysis in the batch solid-state fermentation system.

Abstract

The fermentation process of Chinese baijiu, a distinctive example of batch solid-state fermentation (BSSF), involves the recurrent use of the same raw material to optimize starch utilization. However, it is unclear which microorganisms are able to metabolize low concentration starch effectively. In this study, we successfully identified the key saccharifying microbiota that degraded low-concentration starch in the BSSF system by absolute quantification techniques. The results indicated a 61.93 % enhancement in the efficient utilization of starch, absolute quantification combined with correlation analysis revealed that Geotrichum, Aspergillus, Bacillus, Candida, and Kroppenstedtia were the saccharifying microbiota, with relative abundances exceeding 10 % during fermentation. In the KEGG metabolic pathway, these five saccharifying microbiota had a complete metabolic pathway for degrading starch to d-glucose-1p and d-glucose, including eight related enzymes: maltose phosphorylase, α-amylase, glucoamylase, oligo-1,6-glucosidase, α-glucosidase, pullulanase, α-glucosidase, and maltogenic α-amylase. These studies showed that the saccharifying microbiota can co-degrade starch by multiple saccharifying enzymes, thus improving the utilization of starch substrates.