泸型酒酒醅中梭菌群落的发酵演替规律和功能预测

Role of Clostridia community in fermented grains during Luzhou-flavor liquor production

摘要:

【目的】研究泸型酒酒醅中梭菌(Clostridia)群落的演替规律，探讨梭菌群落在酒醅发酵过程中的潜在功能。【方法】利用实时荧光定量PCR技术结合高通量测序技术研究不同发酵时间泸型酒酒醅中梭菌丰度变化；通过梭菌16S rRNA基因序列高通量测序数据分析揭示梭菌群落演替规律，并运用LEfSe分析找出标志性OTU；通过PICRUSt分析对梭菌功能组成进行预测。【结果】泸型酒发酵过程酒醅中梭菌的生物量在发酵14 d上升至最高 (3.46×107 copies/g)，梭菌占总细菌的相对丰度在发酵20 d达到最高(6.67%)；对梭菌群落结构的聚类分析结果表明，发酵7 d的酒醅梭菌群落结构显著区别于其他发酵时间，主要体现为存在17个标志性OTU，其中大部分分类学地位尚不明确；PICRUSt分析显示梭菌主要参与氨糖与核糖代谢、磷酸戊糖途径，其次是果糖和甘露糖代谢、TCA循环、糖酵解途径、丙酸及丁酸代谢。【结论】泸型酒酒醅中梭菌的生物量和占细菌的相对丰度在发酵开始后的2?3周内逐渐达到最高，而梭菌群落的结构则在发酵1周内便发生了显著改变，并在发酵2?3周内趋于稳定。在发酵2?3周时有较多与丙酸、丁酸等风味物质代谢相关的基因在酒醅梭菌中被预测到。

关键词:泸型酒，酒醅，梭菌，群落演替，功能组成

Abstract:

[Objective] The succession of community structure and potential functional composition of Clostridia in fermented grains of Luzhou-flavor liquor during the fermentation process were studied. [Methods] Real-time quantitative PCR combined with high-throughput sequencing was used to study the dynamics of Clostridia community in fermented grains. 16S rRNA genehigh-throughput sequencing using specific primers was conducted to reveal the succession of Clostridia community. Biomarkers were located on OTU-level through LEfSe analysis. Predictive functional composition of Clostridia community was studied using PICRUSt. [Results] The biomass and relative abundance of Clostridia community reached their maxima at 14 d (3.46×107 copies/g) and 20 d (6.67%), respectively. Clustering analysis showed that the structure of Clostridiacommunity in 7-dsample was significantly different from that in other samples. 17 OTUs were located as biomarkers, and the BLAST results of these OTUs indicated that most of them represented unclassified bacteria. PICRUSt analysis showed that Clostridia community mainly participated in amino sugar and nucleotide sugar metabolism and pentose phosphate pathway followed by fructose and mannose metabolism, citrate cycle, glycolysis, propanoate and butanoate metabolism. [Conclusion] The biomass and the relative abundance of Clostridia community in fermented grains of Luzhou-flavor liquor reached their maxima after being fermented for two to three weeks. The structure of Clostridia community shifted significantly during the first week of fermentation and then gradually recovered in the following two weeks. A number of predictive functional genes related to the metabolism of flavor compounds such as propanoate and butanoate were detected in Clostridia community during 14?21 d of fermentation.

Key words:Luzhou-flavor liquor, Fermented grains, Clostridia community, Succession, Functional composition