1985 Volume 60 Issue 4 Pages 265-275
Numerical classification of strains received as Mycobacterium nonchromogenicum, Mycobacterium terrae and Mycobacterium triviale (Table 1) was carried out, using 81 characters (Table 4) and matching coefficients. The dendrogram prepared by single linkage-clustering showed two “centroid clusters” (Fig. 1 and 2); one consisting of M. nonchromogenicum strains, including type strain NCTC 10424, and another of M. terrae and M. triviale strains, including type strains ATCC 15755 and ATCC 23292. The range of these clusters were determined by the method previously described (Tsukamura, M.: J. Gen. Microbiol., 95: 207-212, 1976) (Table 2), and strains placed outside the centroid clusters were tested whether they enter either or both of these ranges. By this method, 9 strains were identified as M. nonchromogenicum and 8 strains as M. terrae-M. triviale (Table 3). Thus, in total, 33 strains were classified to M. nonchromogenicum and 43 strains to M. terrae- M. triviale. These results well agreed with the results obtained by a M value matrix (Fig. 3). In conclusion, the majority of the strains tested were classified as either M. nonchromogenicum or M. terrae-M. triviale. The strains received as M. terrae or M. triviale formed one cluster and regarded as one taxonomic unit.
The characters of the M. nonchromogenicum and M. terrae-M. triviale thus classified are shown in Table 4. Among these characters, four characters shown in Table 5 were considered as highly useful for differentiating between M. nonchromogenicum and M. terrae-M. triviale. All M. nonchromogenicum strains showed positive reaction in three or more of these four characters, while all M. terrae-M. triviale strains, except for only one strain, showed negative reaction in three or more of these four (Table 6). M. nonchromogenicum strains are clearly differentiated from M. terrae-M. triviale strains by a combination of these four characters.
