A strain representing a rapidly growing, Gram-stain-positive, aerobic, rod-shaped, non-motile, non-sporulating and non-pigmented species of the genus Mycobacterium, designated strain S-I-6T, was isolated from groundwater at Daejeon in Korea. The strain grew at temperatures between 10 and 37 °C (optimal growth at 25 °C), between pH 4.0 and 9.0 (optimal growth at pH 7.0) and at salinities of 0-5 % (w/v) NaCl, growing optimally with 2 % (w/v) NaCl. Phylogenetic analyses based on multilocus sequence analysis of the 16S rRNAgene, hsp65, rpoB and the 16S-23S internal transcribed spacer indicated that strain S-I-6T belonged to the rapidly growing mycobacteria, being most closely related to Mycobacterium sphagni. On the basis of polyphasic taxonomic analysis, the bacterial strain was distinguished from its phylogenetic neighbours by chemotaxonomic properties and other biochemical characteristics. DNA-DNA relatedness among strain S-I-6T and the closest phylogenetic neighbour strongly support the proposal that this strain represents a novel species within the genus Mycobacterium, for which the name Mycobacterium aquiterrae sp. nov. is proposed. The type strain is S-I-6T (=KACC 17600T=NBRC 109805T=NCAIM B 02535T).
Keywords: Mycobacterium aquiterrae sp. nov.; ground water; taxonomy.