Mycobacterium cookii sp. nov.

Strains of a new type of slowly growing scotochromogenic mycobacterium were isolated repeatedly from sphagnum vegetation and surface water of moors in New Zealand. These strains grew at 31 and 22 degrees C but not at 37 degrees C and possessed catalase, acid phosphatase, and arylsulfatase activities. They did not split amides, and most of them were susceptible to antituberculotic drugs. Furthermore, they did not tolerate 0.1% NaOH2 and 0.2% picric acid and did not grow on compounds used as single carbon sources and single nitrogen and carbon sources. The internal similarity of the strains as determined by numerical taxonomy methods was 96.6% +/- 3.09%. The whole-mycolate pattern is unique in that it has not been found previously in 23 species of slowly growing mycobacteria. Evaluation of long-reverse-transcriptase-generated stretches of the primary structure of the 16S rRNA confirmed that these organisms belong to the genus Mycobacterium. The phylogenetic position of these bacteria is unique; they are situated between slowly growing pathogenic and rapidly growing saprophytic species. The strains are not pathogenic for mice, guinea pigs, and rabbits, but they provoke a nonspecific hypersensitivity reaction to bovine tuberculin. Hence, they are considered members of a new species of nonpathogenic, slowly growing mycobacteria, for which the name Mycobacterium cookii is proposed. Strain NZ2 is the type strain; a culture of this strain has been deposited in the American Type Culture Collection as strain ATCC 49103.