[Background] Pit mud quality has a decisive effect on the quality of Chinese strong-aroma type 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.%[背景]窖泥质量决定了浓香型白酒品质的高低,窖泥中的产酸功能菌群显著影响着窖泥的质量及对应的浓香型白酒品质,但目前对窖泥质量的评价尚缺乏明确和完善的标准.[目的]建立一种快速、准确评价窖泥质量的方法,解析窖泥中参与己酸合成的重要微生物.[方法]通过窖泥产酸菌群培养和产酸代谢特征研究,构建厌氧产酸菌群发酵体系,根据窖泥中厌氧菌的己酸合成能力来评价相应窖泥的质量;利用高通量测序技术分析可培养发酵体系中产己酸功能微生物的群落组成.[结果]葡萄糖碳源相比乳酸碳源可以更有效地富集窖泥中的产己酸菌群;采用毫升级别发酵体系、对窖底泥进行多点取样,产酸菌群发酵代谢产物稳定期的己酸产量、己酸/丁酸值可较准确地评价不同窖泥的质量.16S rRNA基因测序结果表明,利用产酸菌群培养方法可以有效地富集未培养产己酸细菌(Uncultured bacterium Caproiciproducens).[结论]基于产酸菌群培养的窖泥微生物发酵体系可用于实际生产中快速、准确地评价窖泥质量,并为窖泥微生物己酸合成代谢机制的研究提供参考.
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