Stefan Klatte

Dietzia, a new genus including Dietzia maris comb. nov., formerly Rhodococcus maris.

Sequencing of the 16S ribosomal DNAs (rDNA) of two strains of Rhodococcus maris was performed to determine the relationship of this species to other mycolic acid-containing actinomycetes. For this purpose we also determined the 16S rDNA sequences for the type species of the genus Rhodococcus, Rhodococcus rhodochrous, and for Mycobacterium chlorophenolicum (formerly Rhodococcus chlorophenolicus), Rhodococcus erythropolis, Gordona bronchialis, and Gordona terrae, for which only partial sequence data have been available previously. The sequences of the two strains of R. maris were identical. The results of a distance matrix analysis indicated that R. maris is not a member of the genus Rhodococcus but is located between members of the genus Corynebacterium and members of the Rhodococcus-Nocardia-Mycobacterium-Gordona-Tsukamurella cluster. The finding that R. maris is phylogenetically isolated is supported by the presence of N-acetyl residues in the glycan moiety of the peptidoglycan and the lack of phosphatidylinositol and phosphatidylinositol mannosides, characteristics which distinguish this taxon from related taxa. On the basis of our results and previous findings, we propose that R. maris should be reclassified in a new genus, Dietzia. The type species is Dietzia maris comb. nov.

Phylogenetic analysis of the genera Rhodococcus and Nocardia and evidence for the evolutionary origin of the genus Nocardia from within the radiation of Rhodococcus species

SUMMARY: 16S rDNA analysis was performed on 32 strains of 26 species of the genera Rhodococcus and Nocardia in order to investigate the phylogenetic structure of these genera within the radiation of other mycolic-acid-containing genera such as Corynebacterium, Dietzia, Gordona, Mycobacterium and Tsukamurella. The genus Rhodococcus shows a complex structure, consisting of six phylogenetically equidistant lineages. The genus Nocardia does not appear to be a sister taxon of Rhodococcus but branches off from within the radiation of Rhodococcus; thus its species can be considered to be derived from a Rhodococcus ancestor. The main known phenotypic feature that separates Nocardia species from those of Rhodococcus appears to be the presence of a cyclic component in menaquinone of the MK-8(H4) type.

Transfer of Rhodococcus aichiensis Tsukamura 1982 and Nocardia amarae Lechevalier and Lechevalier 1974 to the Genus Gordona as Gordona aichiensis comb. nov. and Gordona amarae comb. nov.

We investigated the taxonomic status of Rhodococcus aichiensis DSM 43978T (T = type strain) and Nocardia amarae DSM 43392T by using both chemotaxonomic and genetic methods. The occurrence of MK-9(H2) as the predominant menaquinone, the presence of relatively long-chain mycolic acids (48 to 62 carbon atoms), and the phylogenetic position as determined by a 16S ribosomal DNA sequence analysis provide strong evidence that both R. aichiensis and N. amarae should be transferred to the genus Gordona as Gordona aichiensis and Gordona amarae, respectively.

Rhodococcus opacus sp.nov., An Unusual Nutritionally Versatile Rhodococcus-species

Summary A new Rhodococcus-specics was recognized during a comprehensive study on several unclassified nocardioform bacteria. Representative strains of the new taxon exhibited an unusual wide range of metabolic properties including effective degradation of substituted aromatic compounds with ecological importance. Furthermore, the designated type strain was reportedly capable of chemolithotrophic growth. The new species can be clearly differentiated from other described members of the genus Rhodococcus by lipid and physiological characteristics. Furthermore, the 16S rDNA sequence of the designated type strain has been determined. The name Rhodococcus opacus is proposed for the new species.

Transfer of Polychlorophenol-Degrading Rhodococcus chlorophenolicus (Apajalahti et al. 1986) to the Genus Mycobacterium as Mycobacterium chlorophenolicum comb. nov.

Three independently isolated polychlorophenol-degrading strains of bacteria were characterized on the basis of chemotaxonomic and nutritional characteristics. Previously, these strains were assigned to the species Rhodococcus chlorophenolicus, which was described on the basis of the properties of one of the strains, strain PCP-I(T) (T = type strain) (J. H. A. Apajalahti, P. Kärpänoja, and M. S. Salkinoja-Salonen, Int. J. Syst. Bacteriol 36:246-251, 1986). However, the results of analyses of mycolic acids suggested that these organisms should be transferred to the genus Mycobacterium as Mycobacterium chlorophenolicum. These bacteria have meso-diaminopimelic acid, arabinose, and galactose as cell wall constituents, mycolic acids containing 75 to 80 carbon atoms, and a predominant menaquinone with nine isoprenoid units and one hydrogenated double bond. The fatty acids include mainly straight-chain saturated and monounsaturated fatty acids with 10 to 18 carbon atoms and a large proportion of 10-methyloctadecanoic acid (tuberculostearic acid). The G+C contents of the DNAs of the three strains range from 67 to 69 mol%.

Gordona hydrophobica sp. nov., Isolated from Biofilters for Waste Gas Treatment

The taxonomic position of Gordona sp. strain DSM 44015T, isolated from the packing material of a biofilter used for biological odor abatement of animal rendering emissions, has been clarified by a polyphasic study comprising chemotaxonomic, sequencing, and phenotypic results. The strain possesses a wall chemotype IV, MK-9 (H2), as the predominant menaquinone; relatively long-chain mycolic acids (54 to 62 carbon atoms); and straight-chain, saturated, and monounsaturated fatty acids with considerable amounts of tuberculostearic acid. The polar lipids include phosphatidylethanolamine, and the G+C content of the DNA is 69 mol%. Similarity values for genes encoding 16S rRNA indicate that Gordona sp. strain DSM 44015T represents a new species within the genus Gordona for which the name Gordona hydrophobica is proposed.

Gordona hirsuta sp. nov.

Bacterial strain K718aT (T = type strain), which was isolated from the packing material of a biofilter used for deodorization of animal-rendering plant emissions, was subjected to a polyphasic taxonomic study in which physiological, chemotaxonomic, and genomic methods were used. On the basis of the chemotaxonomic and physiological properties found and the results of 16S ribosomal DNA sequence comparisons, it was evident that strain K718aT belongs to a new species in the genus Gordona. We propose that strain K718a should be the type strain of the new species Gordona hirsuta.

Rhodococcus luteus is a later subjective synonym of Rhodococcus fascians

The results of DNA-DNA hybridization studies and 16S ribosomal DNA sequence comparisons and chemotaxonomic data clearly indicated that Rhodococcus luteus Nesterenko et al. 1982 (O. A. Nesterenko, T. M. Nogina, S. A. Kasumova, E. I. Kvasnikow, and S. G. Batrakov, Int. J. Syst. Bacteriol. 32:1-14, 1982) and Rhodococcus fascians (Tilford) Goodfellow 1984 (M. Goodfellow, Syst. Appl. Microbiol. 5:225-229, 1984) represent a single species. On the basis of priority R. luteus must be considered a later subjective synonym of R. fascians.

Polyphasic classification of Proteobacteria isolated from biofilters

Summary 70 Gram-negative, nonfermenting bacterial isolates from biofilters for off-gas treatment of animal-rendering plant emissions were analyzed for respiratory quinones, polyamine patterns, fatty acid profiles, physiological reaction profiles, and by reverse transcriptase partial sequencing of 16S rRNA. Based on these data, the isolates were grouped into six clusters, which were shown to belong to the alpha- and beta-subclass of the Proteobacteria . Inclusion of fifteen reference strains allowed the assignment of one cluster to the species Brevundimonas diminuta and the assignment of a second cluster to the species Alcaligenes faecalis . The 49 strains of the Brevundimonas diminuta cluster and the clusters F, H, and I were shown to belong to the alpha-subclass of the Proteobacteria. Paracoccus denitrificans evolved as the next neighbour of cluster F. The remaining 21 bacteria containing the beta-subclass specific polyamine 2-hydroxyputrescine grouped either into the Alcaligenes faecalis cluster or formed a distinct group (cluster J) representing a new taxon within the Alcaligenaceae.

Transfer of Arthrobacter picolinophilus tate and ensign 1974 to Rhodococcus erythropolis

The type strain of Arthrobacter picolinophilus, strain DSM 20665 (= ATCC 27854), was found to be so closely related to strains of Rhodococcus erythropolis that we propose that this misclassified taxon should be removed from the genus Arthrobacter and reclassified as a strain of R. erythropolis. Our conclusion is based on the results of a comparative analysis of the chemotaxonomic properties of the organism, including the amino acid composition of the peptidoglycan, the mycolic acid composition, and the fatty acid composition, the very similar physiological properties and 16S ribosomal DNA sequences, and the results of DNA-DNA reassociation experiments performed by the renaturation rate method.