A new rapidly growing mycobacterial species, Mycobacterium morale sp. nov., isolated from the indoor walls of a children's day care centre

Scotochromogenic mycobacterial isolates from water-damaged parts of indoor building materials of a children's day care centre represented a phenetical ly and genetically distinct group of strains. A 16S rDNA dendrogram (1243 b p) showed that the closest species to the new strain MA112/96(T) was Mycoba cterium abscessus, Phylogenetic and phenetic analyses (100 characteristics) grouped the new isolates with M, abscessus, Mycobacterium vaccae, Mycobact erium aurum and Mycobacterium austroafricanum, Ribotyping with Pvull restri ction distinguished the 5 isolates from the other 12 most closely related s pecies by the major bands at 6.5-7 kb and 13-15 kb, The cell morphology of the new isolates was typical of mycobacteria, electron microscopy revealed a triple-layered cell wall with an irregular electron-dense outer layer. Th ey grew at 10-37 degrees C, with no growth at 45 degrees C in 5 d, The gene encoding the secreted 32 kDa protein, specific to mycobacteria, was detect ed by PCR, The main whole-cell fatty acids were characterized by high tuber culostearic acid 10Me-C-18:0 (17% at 28 degrees C), which increased with in creasing growth temperature (22% at 37 degrees C), The other main fatty aci ds were C-18:1 cis9 and C-16:0 (21-20% each), followed by, C-17:1, cis9 (14 %), C-16:1 cis10 (8%) and also a high amount of C-20 alcohol (9%), alpha-My colic acids, keto-mycolates and wax esters were present (C-60-C-90), MK-S(H -2) (90 %) and MK-8(H-2) were the main menaquinones. The cellular phospholi pids were phosphatidylethanolamine, phosphatidylinositol, phosphatidyl inos itolmannosides and diphosphatidylglycerol. Polyamine content was low. G+C c ontent was 72.9 mol%. The new isolates are proposed as a new species, Mycob acterium murals sp. nov. The type strain is MA112/96(T) (= DSM 44340(T)).