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

Abstract:

[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.