锡林郭勒地区鲜马奶中细菌多样性分析

Bacterial diversity of fresh mare’s milk in Xilingol

摘要:

【背景】传统的酸马奶是由鲜马奶自然发酵而成，鲜马奶中的微生物在很大程度上决定了酸马奶的品质。然而，鲜马奶中的微生物组成却鲜有报道。【目的】解析鲜马奶中细菌多样性，比较分析鲜马奶和酸马奶中微生物的差异，探究马奶发酵过程中微生物的变化。【方法】采用PacBio SMRT测序技术，对6份采集自内蒙古锡林浩特牧区的鲜马奶中细菌16S rRNA基因序列全长进行测序，在种水平解析鲜马奶样品的细菌组成，并与前期同一地区的酸马奶菌群组成作对比。【结果】鲜马奶中包含大量的乳酸菌，主要为乳酸乳球菌(12.43%)、格氏乳球菌(3.53%)、肠膜明串珠菌(1.77%)等。此外还有部分板崎肠杆菌等条件致病菌的存在。马奶发酵前后菌群变化较大，鲜马奶中微生物多样性显著高于酸马奶，其中乳酸乳球菌和瑞士乳杆菌为鲜马奶和酸马奶的共有细菌。鲜马奶中的肠膜明串珠菌与乳酸乳球菌、格氏乳球菌呈正相关关系，与嗜水气单胞菌等有害菌为负相关关系，表明在马奶发酵过程中乳酸菌可能会抑制有害菌的生长。【结论】在马奶的发酵过程中，乳酸菌的大量生长抑制了马奶中有害菌生长，降低了马奶中微生物的多样性，提升了酸马奶的品质。为酸马奶的工业化生产提供了参考。

Abstract:

[Background] The traditional koumiss is naturally fermented by fresh mare’s milk, and the quality of koumiss is greatly affected by the bacteria in fresh mare’s milk. However, the microbiota composition in fresh mare’s milk was rarely investigated. [Objective] In order to explore the microbial variation from fresh mare’s milk to koumiss, microbial diversity of fresh mare’s milk was investigated, to provide a reference for the industrialized production of koumiss. [Methods] Six fresh mare’s milk samples were collected from herdsmen families of Xilinhot in Inner Mongolia, China. The bacterial full-length 16S rRNA gene sequences in all samples were sequenced by PacBio SMRT sequencing technology to analyze the bacterial composition and diversity. Meanwhile, the structure and diversity of bacteria in fresh mare’s milk and koumiss were compared. [Results] The results showed a large number of lactic acid bacteria was detected in the fresh mare’s milk such as Lactococcus lactis (12.43%), Lactococcus garvieae (3.53%) and Leuconostoc mesenteroides (1.77%). In addition, some opportunistic pathogens were also detected such as Cronobacter sakazakii. Compared with koumiss, the bacterial diversity in fresh mare’s milk were significantly higher, and Lactococcus lactis and Lactobacillus helveticus were found both in fresh mare’s milk and koumiss. In fresh mare’s milk, Leuconostoc mesenteroides correlated with Lactococcus lactis and Lactococcus garvieae positive, negative related with Aeromonas hydrophila, which implied lactic acid bacteria may suppress pathogen bacteria during the fermentation. [Conclusion] During the fermentation of koumiss, the growth of lactic acid bacteria could inhibit pathogen bacteria, decrease the bacterial diversity and improve the quality of koumiss.