Mycobacterium marseillense sp. nov., Mycobacterium timonense sp. nov. and Mycobacterium bouchedurhonense sp. nov., members of the Mycobacterium avium complex

Abstract

An rpoB sequence-based evaluation of 100 Mycobacterium avium complex (MAC) clinical isolates led to the identification of five respiratory tract isolates that were potential representatives of three novel MAC species. Distinctive phenotypic features of isolates 62863 and 5356591(T) included a pseudomycelium morphology and both esterase and acid phosphatase activities. These two isolates exhibited sequence similarities of 99.8 % for the 16S rRNA gene, 86.3 and 86.1 % for 16S-23S rRNA gene internal transcribed spacer (ITS-1) sequence, 96.7 and 97.8 % for rpoB and 97.6 and 97.4 % for hsp65, respectively, with the type strain of Mycobacterium chimaera, the most closely related species. Isolates 3256799 and 5351974(T) lacked alpha-mannosidase and beta-glucosidase activities. They exhibited sequence similarities of 99.6 % for the 16S rRNA gene, 90.1 and 90.4 % for ITS-1, 97.8 % for rpoB and 98.0 and 98.1 % for hsp65, respectively, with the type strain of M. chimaera, the most closely related species. Isolate 4355387(T) lacked urease and alpha-glucosidase activities, but it exhibited valine arylamidase, cystine arylamidase and acid phosphatase activities. It had sequence similarities of 99.3 % for the 16S rRNA gene, 51.8 % for ITS-1, 97.1 % for rpoB and 97.8 % for hsp65 with the type strain of Mycobacterium colombiense, the most closely related species. A phylogenetic tree based on concatenated 16S rRNA gene, ITS-1, rpoB and hsp65 sequences showed the uniqueness of these five isolates as representatives of three novel species, with bootstrap values >/=95 % in all nodes. On the basis of these phenotypic and genetic characteristics, these five isolates are proposed as representatives of three novel MAC species: Mycobacterium marseillense sp. nov., with strain 5356591(T) (=CCUG 56325(T) =CIP 109828(T) =CSUR P30(T)) as the type strain; Mycobacterium timonense sp. nov., with strain 5351974(T) (=CCUG 56329(T) =CIP 109830(T) =CSUR P32(T)) as the type strain; and Mycobacterium bouchedurhonense sp. nov., with strain 4355387(T) (=CCUG 56331(T) =CIP 109827(T) =CSUR P34(T)) as the type strain.