Multilocus Sequence Typing Of Leuconostoc Mesenteroides From Traditional Dairy Products In Different Regions

This study investigate136Leuconostoc mesenteroides isolated from traditional dairy products in different regions (14strains from Mongolia,30strains from Aba in Sichuan,27strains from Gannan in Gansu,28strains from Chifeng City in Inner Mongolia,22strians from Xilin Gol League in Inner Mongolia,15strains from Hulunbeir League in Inner Mongolia), using multilocus sequence typing method to analyze the nucleotide sequences of nine housekeeping genes (dnaA, pyrG, pepN, rpoB, murE, uvrC, murC, groEL, pheS), then studying the polymorphism and genetic evolution of Leuconostoc mesenteroides. The nucleotide sequence obtained for the housekeeping genes were sequenced in both directions. Allele maps drawn after splicing and checking the nucleotide sequence, determining the sequence of different types and excluding gene mutation and gene reorganization exchange. The G+C content and dN/ds of the nine housekeeping genes analyzed to meet the MLST analysis for the sequence, and the selected housekeeping genes are more conservative. Through analyzing the STs to make the types of136Leuconostoc mesenteroides strains, the following conclusions:(1) Total68STs of136Leuconostoc mesenteroides strains, ST-14which contains a maximum of13Leuconostoc mesenteroides. These STs which constitutes52STs of8type group after eBURST analyzing, and the remaining16STs is a unique type. Each type from the8type group was called CC complex, namely CC55, CC61, CC29, CC16, CC45, CC35, CC28, CC9, respectively. STs was included in CC55up to16. And ST-55is the center of the CC55. Therefore ST-55is considered to be more primitive sequence type.(2) By analyzing the minimum spanning tree showed the genetic evolutionary relationships between136Leuconostoc mesenteroides strains. The results showed positive correlation between the genetic evolutionary relationships and the different regions. Meanwhile, the majority of isolates in different regions is evolved from Gannan in Gansu.(3) The results showed that genetic distances were close between Gannan and Sichuan Aba, from traditional dairy products. The genome of Leuconostoc mesenteroides was changed on the process of making dairy products. But some genes were conserved, and have its own feature.