冷水鱼肠道乳酸菌的遗传差异分析

为分析新疆额尔齐斯河流域及黑龙江流域冷水鱼肠道中乳酸菌遗传差异,为乳酸菌资源的开发奠定基础。本实验利用MRS、Elliker、M17培养基对冷水鱼肠道中低温乳酸菌进行分离鉴定,并测定其最适生长温度。根据16S rRNA基因序列初步确定低温乳酸菌的系统发育关系,并利用rep-PCR指纹图谱技术进一步区分高度同源性菌株。从冷水鱼的肠道中分离得到134株低温乳酸菌,其最适生长温度在15²4℃之间。16S rRNA测序结果表明,这些菌株分别隶属于Lactobacillus、Lactococcus、Enterococcus、Streptococcus、Leuconostoc、Weissella、Carnobacterium 7个属,19个种,其中Lactobacillus为优势菌。Rep-PCR指纹图谱分析表明同一属的乳酸菌在种水平及同一种的不同菌株之间存在不同程度的遗传差异。 

Genetic heterogeneity of lactic acid bacteria isolated from cold-water fish intestine

The purpose of this study was to analyze the genetic and species heterogeneity of lactic acid bacteria ( LAB) from the intestinal tract of cold-water fishes in the Eerqisi river of Xinjiang and Heilong River, which lay the foundation for exploitation resources of lactic acid bacteria.Psychrophilic LAB isolated from cold-water fishes intestinal tract by using MRS, Elliker, M17 culture medium, and measured its optimal growth temperature. According to 16 S rRNA gene sequences preliminarily to determine the phylogenetic relationship of psychrophilic LAB, those highly homologous strains was based on rep-PCR fingerprint to further distinguish.It was obtained that 134 psychrophilic LAB from the gastrointestinal tract of cold-water fishes, and the optimum growth temperature was 15²4 ℃.The sequencing results indicated that the selected psychrophilic LAB were divided into seven genus: Lactobacillus, Lactococcus, Enterococcus, Streptococcus, Leuconostoc, Weissella, Carnobacterium 7 genus, 19 species, respectively, and the dominant bacteria was Lactobacillus. Rep-PCR fingerprint showed that there was a different degree of genetic difference, not only in the same genus of lactic acid bacteria of different species level, but also among various strains of a specie.