Molecular taxonomic evidence for two distinct genotypes of Mycobacterium yongonense via genome-based phylogenetic analysis

Abstract

Recently, we introduced a distinct Mycobacterium intracellulare INT-5 genotype, distantly related to other genotypes of M. intracellulare (INT-1 to -4). The aim of this study is to determine the exact taxonomic status of the M. intracellulare INT-5 genotype via genome-based phylogenetic analysis. To this end, genome sequences of the two INT-5 strains, MOTT-H4Y and MOTT-36Y were compared with M. intracellulare ATCC 13950T and Mycobacterium yongonense DSM 45126T. Our phylogenetic analysis based on complete genome sequences, multi-locus sequence typing (MLST) of 35 target genes, and single nucleotide polymorphism (SNP) analysis indicated that the two INT-5 strains were more closely related to M. yongonense DSM 45126T than the M. intracellulare strains. These results suggest their taxonomic transfer from M. intracellulare into M. yongonense. Finally, we selected 5 target genes (argH, dnaA, deaD, hsp65, and recF) and used SNPs for the identification of M. yongonese strains from other M. avium complex (MAC) strains. The application of the SNP analysis to 14 MAC clinical isolates enabled the selective identification of 4 M. yongonense clinical isolates from the other MACs. In conclusion, our genome-based phylogenetic analysis showed that the taxonomic status of two INT-5 strains, MOTT-H4Y and MOTT-36Y should be revised into M. yongonense. Our results also suggest that M. yongonense could be divided into 2 distinct genotypes (the Type I genotype with the M. parascrofulaceum rpoB gene and the Type II genotype with the M. intracellulare rpoB gene) depending on the presence of the lateral gene transfer of rpoB from M. parascrofulaceum.