食品科学 ›› 2021, Vol. 42 ›› Issue (22): 105-112.doi: 10.7506/spkx1002-6630-20200718-245

• 生物工程 • 上一篇    

老年人肠道乳酸菌的分离与鉴定及其来源发酵乳杆菌的遗传进化分析

张振东,王玉荣,向凡舒,侯强川,李宝坤,郭壮   

  1. (1.湖北文理学院 湖北省食品配料工程技术研究中心,湖北 襄阳 441053;2.石河子大学食品学院,新疆 石河子 832000)
  • 发布日期:2021-11-23
  • 基金资助:
    国家自然科学基金青年科学基金项目(31501455);新疆建设兵团农业领域重点科技攻关项目(2018AB015); 新疆建设兵团高新技术领域重点科技攻关项目(2018AB010)

Isolation and Identification of Lactic Acid Bacteria from the Elderly Gut and Genetic Evolution of Isolated Lactobacillus fermentum

ZHANG Zhendong, WANG Yurong, XIANG Fanshu, HOU Qiangchuan, LI Baokun, GUO Zhuang   

  1. (1. Hubei Provincial Engineering and Technology Research Center for Food Ingredients, Hubei University of Arts and Science, Xiangyang 441053, China; 2. College of Food Science, Shihezi University, Shihezi 832000, China)
  • Published:2021-11-23

摘要: 首先对湖北襄阳和恩施地区的健康老年人肠道乳酸菌进行分离与鉴定,然后从中选择发酵乳杆菌(Lactobacillus fermentum)进行多位点序列分型(multilocus sequence typing,MLST)分析。结果显示,基于可培养方法,湖北襄阳与恩施地区老年人肠道乳酸菌可以鉴定为以乳杆菌属(Lactobacillus)为主的5 个菌属,15 个种。总的来说,发酵乳杆菌和唾液乳杆菌(L. salivarius)占老年人肠道源乳酸菌分离株总量的55%左右,表明人体肠道可以作为发酵乳杆菌的重要分离来源。基于8 个持家基因的MLST分析表明,25 株来源于肠道的发酵乳杆菌可以划分为25 个序列型,具有极高的遗传多样性;基于选择压力分析与phi-test,选用的8 个持家基因均受到纯化选择作用,且其中仅基因rpoB显著经历了基因重组事件;另外,基于Prim’s和goeBURST的进化分析表明,一半左右的肠道源发酵乳杆菌倾向于形成单独的分支,表明它们具有一定的宿主特异性,可能的原因是为适应肠道环境,这些发酵乳杆菌经历了有异于发酵食品生境的进化历程。

关键词: 老年人肠道;乳酸菌;多位点序列分型;发酵乳杆菌;持家基因

Abstract: In this study, we isolated and identified lactic acid bacterial (LAB) strains from the gut of healthy elderly people in Xiangyang and Enshi, Hubei and then selected Lactobacillus fermentum strains for analysis by multilocus sequence typing (MLST). Results showed that by cultivable methods, 15 species of LAB were obtained belonging to five genera with Lactobacillus being the single dominant genus. In general, L. fermentum and L. salivarius account for about 55% of the total intestinal LAB strains, indicating that the human intestine can be an important source of L. fermentum. MLST analysis based on eight housekeeping genes showed that 25 L. fermentum strains originating from the elderly gut could be divided into 25 sequence types (ST), indicating high genetic diversity. Selection pressure analysis and phi-test showed that the eight housekeeping genes were purified and selected, and among these only the gene rpoB experienced recombination events. In addition, the evolutionary analysis based on Prim’s algorithm and global optimal BURST (goeBURST) algorithm showed that nearly half of the intestinal L. fermentum strains had the tendency to form one single branch, indicating that they had host specificity. This may be due to adaption to the intestinal environment. These strains were likely to undergo an evolutionary process different from that in fermented food habitat in order to adapt to the intestinal environment.

Key words: elderly gut; lactic acid bacteria; multilocus sequence typing; Lactobacillus fermentum; house-keeping genes

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