内蒙古地区传统制作奶豆腐和乌日莫中乳酸菌多样性及分布特征

Diversity and distribution characteristics of lactic acid bacteria isolated from traditional milk curd and Urimo in Inner Mongolia

【背景】传统制作奶豆腐和酸性奶油(乌日莫)是内蒙古农牧地区最喜爱的食品,蕴含着十分丰富的乳酸菌资源,亟待开发利用。【目的】通过解析内蒙古农牧地区传统自制奶豆腐和乌日莫样品中乳酸菌多样性及分布特征,为优良菌株选育与利用提供资源和理论基础。【方法】采用稀释涂布法分离纯化乳酸菌,测定菌株16S rRNA基因序列鉴定种属关系,阐明乳酸菌系统发育、遗传分化及菌群结构。【结果】传统自制样品中共分离得到乳酸菌81株,主要归属于乳酸片球菌(Pediococcus acidilactici)、戊糖片球菌(Pediococcus pentosaceus)、短乳杆菌(Lactobacillus brevis)、瑞士乳杆菌(Lactobacillus helveticus)、副干酪乳杆菌(Lactobacillus paracasei)、食二酸乳杆菌(Lactobacillus diolivorans)、奥塔基乳杆菌(Lactobacillus otakiensis)、植物乳杆菌(Lactobacillus plantarum)、开菲尔乳杆菌(Lactobacillus kefir)、乳酸乳球菌(Lactococcus lactis)、粪肠球菌(Enterococcus faecalis)、屎肠球菌(Enterococcus faecium)和坚忍肠球菌(Enterococcus durans)这13个种,其中屎肠球菌和乳酸乳球菌分别为奶豆腐和乌日莫的优势种。乳酸菌的菌群结构单一,核苷酸多态性(π)较低,遗传距离(Dxy)较远,基因交流指数(Nm)较低。【结论】奶豆腐和乌日莫中乳酸菌生物多样性较高,菌种之间的亲缘关系与地理分布呈非相关性,在进化历史上发生基因重组和基因交流的频率较低,表现出较强的遗传稳定性。

[Background]Traditional milk curd and sour cream butter(Urimo)are the most popular food in Inner Mongolia,which contains abundant lactic acid bacteria resources to be developed and utilized urgently.[Objective]The diversity and distribution characteristics of lactic acid bacteria in traditional homemade milk curd and Urimo samples were analyzed to provide resources and theoretical basis for breeding and utilization of superior strains.[Methods]Lactic acid bacteria were isolated and purified by spread plate method.The phylogenetic relationship,genetic differentiation and community structure of these strains were illustrated based on the sequences of gene 16S rRNA and the species was identified.[Results]A total of 81 strains of lactic acid bacteria were isolated from the traditional homemade samples,mainly belonging to 13 species such as Pediococcus acidilactici,Pediococcus pentosaceus,Lactobacillus brevis,Lactobacillus helveticu,Lactobacillus paracasei,Lactobacillus diolivorans,Lactobacillus otakiensis,Lactobacillus plantarum,Lactobacillus kefir,Lactococcus lactis,Enterococcus faecalis,Enterococcus faecium and Enterococcus durans.Among them,Enterococcus faecium and Lactococcus lactis were the dominant species of milk curd and Urimo,respectively.The single microbial community structure,low nucleotide polymorphism(π),long genetic distance(Dxy),and low gene flow index(Nm)among these lactic acid bacteria were confirmed here.[Conclusion]The biodiversity of lactic acid bacteria in milk curd and Urimo was high,and no correlation was found between species and geographical distribution.There was a strong genetic stability because of the low frequency of gene recombination and exchange in the evolutionary history of lactic acid bacteria.