Abstract:The aim of this study was to investigate the feasibility of multilocus sequence typing for Streptococcus thermophilus. Multilocus sequence typing technology was used to genotype eight in-house S. thermophilus strains and an additional six S. thermophilus strains for which whole-genome sequences have been published. The homology of these strains was also analyzed. Phenotypic characteristics including acid production rate and protein hydrolysis were determined for the eight in-house S. thermophilus strains. The results showed that these eight strains belonged to four genotypes, whereas the other six strains belonged to five genotypes. The phylogenetic relationships among all strains varied. Among them, ND03, MN-ZLW-002, and 0#, isolated from China, had relatively high homology; 09086, 09087, and 09088, isolated from Xinjiang yogurt, had relatively high homology; 09067, 09078, and 09079, isolated from Inner Mongolia yogurt, and JIM8232, isolated from French yogurt, had relatively high homology; and s4, isolated from a French fermentation agent, and CNRZ1066, isolated from French yogurt, had relatively high homology. The acid production rates and protein hydrolysis of the eight in-house strains were strain specific, and the phenotypic properties were largely in accord with the genotypes. In summary, multilocus sequence typing is effective for the genotyping of S. thermophilus strains.
