Mycobacterium sediminis sp. nov. and Mycobacterium arabiense sp. nov., two rapidly growing members of the genus Mycobacterium

Abstract

Two novel isolates of rapidly growing, Gram-stain-positive, non-chromogenic species of the genus Mycobacterium , strain YIM M13028T from a sediment sample collected from the South China Sea (19° 30.261′ N 111° 0.247′ E) at a depth of 42 m and strain YIM 121001T from a coastal zone sand sample collected in Dubai, United Arab Emirates, were obtained in our laboratory. Their taxonomic positions were determined by a polyphasic approach. Good growth of the two strains was observed at 28 °C and pH 7.0 with 0–2 % NaCl on tryptic soy agar medium. Both strains formed round orange–red colonies, strain YIM M13028T had a rough surface, while YIM 121001T was smooth. Cellular fatty acids, whole-cell protein profiles and TLC analysis of their mycolic acids show significant differences from reference stains. Phenotypic characteristics and multilocus sequence analysis (MLSA) of 16S rRNA gene, hsp65, rpoB and 16S–23S internal transcribed spacer (ITS) sequences indicated that both strains YIM M13028T and YIM 121001T belong to the genus Mycobacterium . DNA–DNA hybridization values revealed a low relatedness (<70 %) of the two isolates with the type strains Mycobacterium neoaurum DSM 44074T and Mycobacterium hodleri DSM 44183T. The low DNA–DNA hybridization values (40.4±3.5 %) between strains YIM M13028T and YIM 121001T and phenotypic distinctiveness indicated that the two strains were representatives of different novel species of the genus Mycobacterium . The names proposed for these novel species are Mycobacterium sediminis sp. nov. and Mycobacterium arabiense sp. nov., and the type strains are YIM M13028T ( = DSM 45643T = KCTC 19999T) and YIM 121001T ( = DSM 45768T = JCM 18538T), respectively.