Numerical Analysis of the Relationship Between Mycobacterium, Rhodochrous Group, and Nocardia by Use of Hypothetical Median Organisms

Matsumoto

et al. 1979

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A numerical analysis of 369 strains received as members of the genus Mycobacterium, Rhodococcus (formerly Gordona) , Nocardia, or Corynebacterium was carried out using 88 characters. Of the strains tested, 345 mycobacteria, rhodococci, and nocardiae formed four distinct clusters at a similarity level of 85%. The first cluster was composed of slowly growing mycobacteria; the second cluster, of strains of Mycobacterium flavescens and M. thermoresistibile; the third cluster, of strains of rapidly growing mycobacteria; and the fourth cluster, of strains of Rhodococcus and Nocardia. Strains of three species of rapidly growing mycobacteria, M. agri, M. smegmatis, and M. vaccae, were located outside of these clusters. The fourth cluster could be divided into three subclusters, one consisting of rhodococci plus some strains of Nocardia asteroides, a second consisting of the remaining strains of Nocardia, and a third consisting of strains of Rhodococcus aurantiacus (Gordona aurantiaca) and Jensenia canicruria.Mycobacterium, Rhodococcus (formerly Gordona), and Nocardia are closely related taxa belonging to the order Actinomycetales (21).In 1966, Tsukamura (13) reported that mycobacteria can be divided into two subgroups, which roughly correspond to slowly growing and rapidly growing mycobacteria, by numerical classification. These two subgroups differed from each other not only in growth rate, but also in several biological characters. Subsequently, Tsukamura and Mizuno (14, 24) proposed the subgeneric names Mycobacterium and Mycomycobacterium for these subgroups. Later, after having compared mycobacteria and nocardiae, Tsukamura (17) recommended that the subgenera Myco bacterium (slowly growing mycobacteria) and Mycomycobacterium (rapidly growing mycobacteria) be elevated to genus status, i.e., taxa equivalent in status to the genus Nocardia.In 1971, Tsukamura (18) proposed a new genus, Gordona, for slightly acid-fast organisms considered to be intermediate between Mycobacterium and Nocardia and placed it in the family Actinomycetaceae, to which the genus Nocardia belongs. It was later shown by Tsukamura that the genus Gordona contained strain ATCC 13808 of Rhodococcus rhodochrous (19), and it was stated that the generic name Gordona should be changed to Rhodococcus (20), as this is the first name used for an organism belonging to the genus proposed. Independently, Goodfellow (2) observed that "Mycobacterium" rhodochrous differs from nocardiae, and Goodfellow et al. (4) reported that it also differs from rapidly growing mycobacteria.The finding that "M. " rhodochrous differs from both Mycobacterium and Nocardia was conf m e d by an international cooperative study (5). Goodfellow and Alderson (3) also proposed the name Rhodococcus for the "M. " rhodochrous complex, in which they included the genus Gordona. These authors also included several new species in the genus Rhodococcus.The taxonomic relationships of the mycobacteria, rhodococci, and nocardiae were studied by Tsukamura (21), who included hypothetical median organi...

Section: Discussionsupporting

confidence: 55%

“…These clusters were composed of: (A) slowly growing mycobacteria; (B) intermediate mycobacteria; (C) rapidly growing mycobacteria; and (D) rhodococci and nocardiae. Previously, Tsukamura (17,21) (thiopene-2-carboxylic acid hydrazide), nitrate reduction, and the 2-week aryhlfatase test. These two subgroups form the TB complex.…”

Section: Discussionmentioning

confidence: 99%

Comprehensive Numerical Classification of 369 Strains of Mycobacterium, Rhodococcus, and Nocardia

Matsumoto

et al. 1979

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“…To date, only a few numerical taxonomy studies of rapidly growing, scotochromogenic mycobacteria have been reported (8,22,27,30). In these studies, M. neoaurum was not clearly separated from M. parafortuitum (€9, and "M. tokaiense" was not clearly distinguished from "M. chubuense" (27).…”

Section: Discussionmentioning

confidence: 99%

Numerical Analysis of Rapidly Growing, Scotochromogenic Mycobacteria, Including Mycobacterium obuense sp. nov., nom. rev., Mycobacterium rhodesiae sp. nov., nom. rev., Mycobacterium aichiense sp. nov., nom. rev., Mycobacterium chubuense sp. nov., nom. rev., and Mycobacterium tokaiense sp. nov., nom. rev.

Matsumoto

1981

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We performed numerical analyses of 155 strains of rapidly growing, scotochromogenic mycobacteria by two different methods; in one method we used 104 characters, and in the other we used 84 characters. The following taxa appeared as distinct clusters: Myco bacterium thermoresistibile, Myco bacterium flavescens, Mycobacterium duvalii, Mycobacterium phlei, "Mycobacterium o buense," Myco bacterium parafortuitum, Mycobacterium vaccae, Mycobacterium sphagni, "Mycobacterium aichiense," "Mycobacterium rhodesiae," Mycobacterium neoaurum, "Mycobacterium chubuense," "Myco bacterium tokaiense," and Mycobacterzum komossense (names in quotation marks are not on the ApprovedLists of Bacterial Names). M. flavescens strains were divided into two subgroups, one consisting of strains isolated in Japan and the other consisting of strains isolated in Rhodesia and strains received from the American Type Culture Collection, including the type strain of M. flavescens (ATCC 14474). We found that there are many species of rapidly growing, scotochromogenic mycobacteria, and we believe that new species should be recognized and named on the basis of at least three strains. The following species appeared to be distinct from all presently named species: "Mycobacterium gallinarum," "Mycobacterium armentun," "Mycobacterium pelpallidurn," and "Mycobacterium taurus." However, each of these species was proposed on the basis of only one or two strains. Because of the small number of strains studied, formal proposals for these species should not be made until more strains of each taxon are studied. Furthermore, we consider "Myco bacterium magistrae" and "Myco bacterium auratum" to be synonyms of M. flavescens, "Mycobacterium pallidum" to be a synonym of M. parafortuitum, "Mycobacterium liquefactum" to be a synonym of M. vaccae, and "Mycobacterium sufflavum" to be a synonym of M. neoaurum. "M. obuense," "M. rhodesiae," "M. aichiense," "M. chubuense," and "M. tokaiense" are not on the Approved Lists of Bacterial Names, but based on the results of this study, we consider these organisms distinct species. Therefore, these names are revived for the same organisms with which they were originally associated. The type strains of these species are strain 47001 (=ATCC 27023 =NCTC 10778), strain 02002 (=ATCC 27024 -NCTC 10779), strain 49005 (=ATCC 27280 =NCTC 10820), strain 48013 (=ATCC 27278 =NCTC 10819), and strain 47503 (=ATCC 27282 =NCTC 10821), respectively. Mycobacterium flavescens

“…The set of characters shown in Table 2 was used for analysis of the relationship among Mycobacteriurn, Gordona, and Nocardia (23). Only 57 of these characters were effective for differentiation between Nocardia strains (omitting strain 71, which is now identified as Mycobacterium intracellulare).…”

Section: Materlals and Methodsmentioning

confidence: 99%

Extended Numerical Taxonomy Study of Nocardia

1977

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Numerical classification of 80 strains received as Nocardia using six different sets of characters was carried out. A set of 57 "differentiating" characters gave six distinct clusters: Nocardia farcinica, N . asteroides A, N . asteroides B, N . caviae, N. brasiliensis, and Gordona lentifragmenta (formerly, N . rubra) . Hence, the strains received as N. asteroides were divided into three subgroups, N . farcinica, N . asteroides A, and N . asteroides B. The cluster of G. lentifragmenta was placed apart from the others, and a previous classification of this taxon as a species of Gordona was supported by the present study. The problem of a minimum number of differentiating characters necessary for numerical classification, which was considered theoretically as above 40 or 50, was studied experimentally in this study. The results supported the theoretical considerations. Inclusion of linked characters reduced the number of clusters.Previous studies on the taxonomy of Nocardia were made by Gordon and Mihm (6-9) by use of physiological and biochemical characters. Many species were merged into a few species. Gordon and Mihm (6, 8) included the strain ATCC 3318, labeled as Nocardia farcinica, in the species Nocardia asteroides. The first numerical classification of Nocardia was carried out by Cerbon (3). He suggested that the species N . asteroides be divided into several subgroups. Subsequently, Tsukamura (22) carried out a numerical classification of Nocardia using a large number of characters and reported that the strains received as N . asteroides were divided into two distinct taxa. In this study, the strain ATCC 3318 of N . farcinica was included in one cluster. Hence, this cluster was named N . farcinica and another cluster was designated N. asteroides. These two taxa could be differentiated by several characters. The former grew at 45"C, showed acetamidase and benzamidase activities, formed acid from rhamnose, and utilized 1,3-butylene glycol as sole carbon source and acetamide and monoethanolamine as simultaneous nitrogen and carbon sources; the latter taxon did not. This finding was supported by Berd ( l ) , Holm (lo), and Franklin and McClung (4) by use of the same phenetic analysis, and by Bradley (2) and Franklin and McClung (4) by use of a deoxyribonucleic acid hybridization technique. Magnusson and Mariat (14) suggested that, by using a delayed type skin reaction, M. farcinica be separated from N. asteroides.At a later date, Goodfellow (5) and Kurup and Schmitt (11) reported that the species N . asteroides is divided into five and four subgroups, respectively. Goodfellow used none of the same strains as used by Tsukamura (22), and Kurup and Schmitt stated that one of their subgroups was identical to Tsukamura's N . farcinica.The present study was carried out for two reasons: (i) to reinvestigate the heterogeneity of N. asteroides by use of a new set of characters which included several characters not used previously, and (ii) to observe the relationship between the clustering and the characters used in the...