Abstract:[Background] Pit mud quality has a decisive effect on the quality of Chinese strong-aromatype liquor. Acidogenic microbiota from pit mud significantly influence pit mud quality together with quality of the liquor. However, the evaluation criteria of pit mud quality are not very clear and accurate so far. [Objective] We aimed at establishing a quick and accurate method to evaluate pit mud quality in this study. Meanwhile, we analyzed functional microorganisms possibly participating in caproate production. [Methods] A cultivation method was developed to culture acidogenic microbiota. The concentration and ratio of subsequent metabolites were used to evaluate the caproate-producing capability of pit mud bacteria, as well as the corresponding pit mud quality. High-throughput sequencing technique was used to analyze the microbiota composition in the cultivation system. [Results] Compared to lactate and acetate, using glucose as the carbon source could effectively enrich caproate-producing microbiota in pit mud, resulting in higher caproate production. Small volume culturing and statistical sampling were determined. The concentration of caproate and the ratio of caproate to butyrate at the stationary phase of microbiota fermentation, could be served as accurate and stable indicators to evaluate pit mud quality. 16S rRNA gene sequencing showed that Uncultured bacterium Caproiciproducens were effectively enriched in the cultivation system. [Conclusion] Model system based on pit mud cultivation could be used to quickly evaluate pit mud quality in factories, and provides an approach to analyze caproate formation mechanism with pit mud microbiota.
