Mycolicibacterium chengduense sp. nov. and Mycolicibacterium sichuanense sp. nov., carrying multiple virulence-associated genes, recovered from human sputa

Two mycobacterial strains, 120266 T and 050158 T , were isolated from clinical sputum samples of distinct patients at a hospital in Chengdu, China, in 2020 and 2023, respectively. The two strains were subjected to whole-genome sequencing. A phylogenomic tree based on 1,862 concatenated core proteins showed that the two strains were clustered within the genus Mycolicibacterium . The average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH) values were calculated between each of the two strains and the type strains of all currently known Mycolicibacterium species. The two strains represented two novel species, as their highest ANI and dDDH values with the type strains of all currently known Mycolicibacterium species fell below the species demarcation thresholds (95% for ANI and 70% for dDDH). Subsequent physiological and biochemical analyses revealed that the biochemical traits and overall fatty acid profiles of strains 120266 T and 050158 T were largely consistent with those of known Mycolicibacterium species. Nevertheless, the two novel species can be differentiated from other Mycolicibacterium species by certain biochemical characteristics. In conclusion, strains 120266 T and 050158 T represent two novel species of the genus Mycolicibacterium , for which we propose Mycolicibacterium chengduense sp. nov. and Mycolicibacterium sichuanense sp. nov. as the species names. The type strains of M. chengduense sp. nov. and M. sichuanense sp. nov. are 120266 T (=GDMCC 1.4435 T =JCM 37531 T ) and 050158 T (=GDMCC 1.4511 T =JCM 37529 T ), respectively.