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

Area of Science:

• Microbiology
• Biotechnology
• Food Science

Background:

• Chinese baijiu production utilizes batch solid-state fermentation (BSSF), repeatedly using raw materials to maximize starch conversion.
• The specific microorganisms responsible for effectively metabolizing low-concentration starch in this process remain largely unidentified.

Purpose of the Study:

• To identify the key saccharifying microbiota involved in low-concentration starch degradation within the BSSF system of Chinese baijiu.
• To elucidate the metabolic pathways and enzymatic mechanisms employed by these microorganisms for enhanced starch utilization.

Main Methods:

• Utilized absolute quantification techniques to identify and enumerate microorganisms.
• Performed correlation analysis between microbial abundance and starch degradation.
• Analyzed metabolic pathways using the Kyoto Encyclopedia of Genes and Genomes (KEGG) database.

Main Results:

• Identified Geotrichum, Aspergillus, Bacillus, Candida, and Kroppenstedtia as the primary saccharifying microbiota, each with relative abundances over 10%.
• Demonstrated a 61.93% enhancement in efficient starch utilization.
• Revealed a complete metabolic pathway for starch degradation to d-glucose-1-phosphate and d-glucose, involving eight key enzymes.

Conclusions:

• The identified saccharifying microbiota, through synergistic action and multiple enzymes, effectively degrade starch substrates.
• This co-degradation mechanism significantly improves starch utilization efficiency in Chinese baijiu BSSF.
• The findings provide crucial insights for optimizing fermentation processes and enhancing yields.