MLST analysis of genetic diversity of Bacillus coagulans strains to evaluate effects on constipation model

Bacillus coagulans can help ameliorate or prevent gastrointestinal diseases, but the genetic relationships among B. coagulans isolates are not well studied. Multilocus sequence typing analysis was conducted on 57 isolates of B. coagulans from 22 provinces or autonomous regions in China. B. coagulans isolates were highly diverse and a total of 33(sequence typings) STs were found. These isolates had a weak clonal population structure and strong indications of intraspecies recombination. The evolution direction of B. coagulans was not correlated with geography or isolation source. Fifteen strains were selected for further analysis based on proximity relationships from the phylogenetic tree. Five isolates(B. coagulans-1, B. coagulans-10, B. coagulans-39, B. coagulans-70 and B. coagulans-71) with good spore-forming ability relative to the rest of the isolates were evaluated for constipation relief. B. coagulans-39 significantly relieved constipation symptoms in mice by regulating intestinal flora, increasing the production of short-chain fatty acids and restoring the level of gastrointestinal regulatory peptides. Comparative genomic analysis showed the beneficial effects of B. coagulans-39 might be associated with specific functional genes that are involved in the utilization of various carbohydrates as primary substrates and short-chain fatty acid production.

Genomic compositions and phylogenetic analysis of Shigella boydii subgroup

Comparative Genomic Hybridization (CGH) microarray analysis was used tocompare the genomic compositions of all eighteen Shigella boydii serotype representative strains.The results indicated the genomic ''backbone'' of this subgroup contained 2552 ORFs homologous tononpatho-genic E. coli K12. Compared with the genome of K12199 ORFs were found to be absent in allS. boydii serotype representatives, including mainly outer membrane protein genes and O-antigenbiosynthesis genes. Yet the specific ORFs of S. boydii subgroup contained basically bacteriophagegenes and the function unknown (FUN) genes. Some iron metabolism, transport and type Ⅱ secretionsystem related genes were found in most representative strains. According to the CGH phylogeneticanalysis, the eighteen S. boydii serotype representatives were divided into four groups, in whichserotype C13 strain was remarkably distinguished from the other serotype strains. This groupingresult corresponded to the distribution of some metabolism related genes. Furthermore, the analysisof genome backbone genes, specific genes, and the phylogenetic trees allowed us to discover theevolution laws of S. boydii and to find out important clues to pathogenesis research, vaccinationand the therapeutic medicine development.