不同培养条件对罗非鱼肠道乳酸菌分离的影响

Effects of the culture conditions on the separation of intestinal lactic acid bacteria in tilapia

为了解罗非鱼肠道乳酸菌群多样性和优势菌种,促进乳酸菌在罗非鱼养殖中的应用,采用MRS、M17、TPY、Elliker四种培养基,分别在有氧、厌氧以及30℃、37℃和45℃温度条件下分离罗非鱼肠道乳酸菌,分析不同培养基、培养温度、有氧和厌氧条件对罗非鱼肠道乳酸菌分离的影响;并对分离到的菌株进行分子鉴定和16S r RNA序列分析,构建系统发育树,比较不同分离条件下分离肠道乳酸菌的遗传多样性.结果表明,不同培养基对罗非鱼肠道乳酸菌的分离效果有一定的差异,其中MRS培养基的分离效果最好,且遗传多样性最高;37℃较30℃对乳酸菌的分离更加有利,45℃未分离到乳酸菌;有氧条件下共分离出8种33株乳酸菌,主要为杆菌;厌氧条件下得到10种24株乳酸菌,主要为球菌.共分离到植物乳杆菌(Lactobacillus plantarum)29株,可能是罗非鱼肠道优势乳酸菌种.本研究可为开发水产养殖肠道乳酸菌提供依据,并推广到其他种类的鱼肠道乳酸菌的分离和鉴定.

This reseach aimed to analyze and understand the diversity of intestinal lactic acid bacteria flora of tilapia,To determine the advantage strain,and to provide certain theoretical basis for the application of lactic acid bacteria in the tilapia fish breeding industry.We used 4 kinds of culture medium including MRS,M17,TPY and Elliker to separate the intestinal lactic acid bacteria of tilapia at the temperatures of 30 ℃,37 ℃ and 45 ℃ under aerobic and anaerobic conditions,respectively.The isolated strains were identified by molecule technology and 16 S rRNA sequence analysis.Phylogenetic tree were established to compare the genetic diversity of lactic acid bacteria isolated from intestinal tract with different media.Results showed different results from separation with different culture media of lactic acid bacteria from tilapia intestines.The MRS culture medium was the best and had the highest genetic diversity.37 ℃ was more advantageous than 30 ℃ for the separation of lactic acid bacteria,while no lactic acid bacteria was isolated at 45 ℃.Under aerobic condition,33 lactic acid bacteria isolates belonging to 8 species were separated;and 24 lactic acid bacteria isolates belonging to 10 species were separated in anaerobic condition.The experiment separated29 strains of Lactobacillus plantarum,which were probably the advantage intestine lactic acid bacterium in tilapia.The results indicated that the combination of different culture medium,culture temperature and aerobic/anaerobic condition is benefit for the separation of intestinal lactic acid bacteria in tilapia.Such result provides basis for the exploitation of intestinal aquaculture lactic acid bacteria and can be generalized to the separation of lactic acid bacteria in other fishes.