芝麻香型白酒发酵过程中乳酸菌多样性及其演替规律

Diversity and succession of lactic acid bacteria during sesame-flavor liquor fermentation

摘要:

【背景】乳酸菌是白酒发酵过程中一类非常重要的微生物，其种类及动态变化对于白酒品质具有重要影响。然而，目前对于芝麻香型白酒发酵过程中乳酸菌群落结构及其演替规律的认识并不全面。【目的】揭示芝麻香型白酒发酵过程中乳酸菌的多样性及菌群的演替规律，为更好地探索白酒酿造机理和控制白酒品质提供生物学依据。【方法】利用高通量测序技术对芝麻香型白酒发酵过程中乳酸菌菌群演替进行跟踪分析，同时采用实时荧光定量PCR对发酵过程中乳酸菌的生物量进行定量分析。【结果】高通量测序结果显示，芝麻香型白酒发酵过程涉及5个属的乳酸菌：魏斯氏菌属(Weissella)、片球菌属(Pediococcus)、乳杆菌属(Lactobacillus)、明串珠菌属(Leuconostoc)和乳球菌属(Lactococcus)，共计43种乳酸菌。其中，在发酵过程中平均相对丰度大于0.5%的乳酸菌有10种，分别是类肠膜魏斯氏菌(Weissella paramesenteroides)、食窦魏斯氏菌(Weissella cibaria)、融合魏斯氏菌(Weissella confusa)、戊糖片球菌(Pediococcus pentosaceus)、假肠膜明串珠菌(Leuconostoc pseudomesenteroides)、发酵乳杆菌(Lactobacillus fermentum)、植物乳杆菌(Lactobacillus plantarum)、副干酪乳杆菌(Lactobacillus paracasei)、耐酸乳杆菌(Lactobacillus acetotolerans)和Lactobacillus sp.。在堆积发酵过程中，Weissella属占细菌总量的50%以上，其次是Pediococcus属和Lactobacillus属，而Leuconostoc属和Lactococcus属相对较少。在窖池发酵过程中Lactobacillus属的乳酸菌逐渐成为优势细菌，尤其是Lactobacillus sp.在窖池发酵中后期相对丰度达到80%以上。实时荧光定量PCR结果显示，在堆积发酵和窖池发酵前期乳酸菌总量变化不大；从窖池发酵5 d开始，乳酸菌总量迅速上升，30 d时达到最大值。【结论】对白酒发酵过程中乳酸菌种类及动态变化的研究有助于探究白酒酿造过程中乳酸菌功能，进而解析白酒酿造机理，最终达到控制白酒品质的目的。

Abstract:

[Background] Lactic acid bacteria are important in liquor fermentation, and the diversity and succession of lactic acid bacteria have important influence on liquor quality. However, the structure and succession of lactic acid bacteria communities are not clear during sesame-flavor liquor fermentation. [Objective] We studied the diversity and succession of lactic acid bacteria communities during sesame-flavor liquor fermentation for better process control and product quality. [Methods] High-throughput sequencing was used to analyze lactic acid bacteria communities during sesame-flavor liquor fermentation. Biomass of lactic acid bacteria was quantified by real-time qPCR. [Results] Lactic acid bacteria in sesame-flavor liquor fermentation included Weissella, Pediococcus, Lactobacillus, Leuconostoc, and Lactococcus, classified to 43 species. Ten species of lactic acid bacteria were observed higher than 0.5%, including Weissella paramesenteroides, Weissella cibaria, Weissella confuse, Pediococcus pentosaceus, Leuconostoc pseudomesenteroides, Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus paracasei, Lactobacillus acetotolerans and Lactobacillus sp.. In heap-fermentation stage, Weissella was more than half of the total bacteria, followed by Pediococcus and Lactobacillus. Leuconostoc and Lactococcus were present in low numbers. In pit-fermentation stage, Lactobacillus became the predominant bacteria, and the relative abundance of Lactobacillus sp. was up to 80% in the mid and later stage of pit-fermentation. During heap-fermentation and the early stage of pit-fermentation, the biomass of lactic acid bacteria changed little. After 5 days of pit-fermentation, the biomass of lactic acid bacteria increased fast, and reached the maximum at 30 days. [Conclusion] The knowledge of diversity and succession of lactic acid bacteria during sesame-flavor liquor fermentation will help understand the roles of lactic acid bacteria in liquor production with better process control and product quality.