Kazunori Hatano

Union of the genera Microbacterium Orla-Jensen and Aureobacterium Collins et al. in a redefined genus Microbacterium.

The 16S rRNA gene sequences of 19 strains, 11 strains representing validated Aureobacterium or Microbacterium species and eight strains of non-valid species or isolates, were determined. These sequences were aligned with the sequences of other validated Aureobacterium and Microbacterium species and related actinobacteria. A comparative sequence analysis of 43 strains revealed that the species of the genera Aureobacterium and Microbacterium form a monophyletic association in which species of both genera are intermixed. The high similarity in phylogenetic properties found in the species within both genera and the close relationship in physiological and chemotaxonomic features other than the diamino acid in the cell wall, provided strong evidence that the genera Aureobacterium and Microbacterium should be unified. An emended genus Microbacterium is proposed for the two combined genera. The following validated Aureobacterium species were combined to the genus Microbacterium: Aureobacterium arabinogalactanolyticum to Microbacterium arabinogalactanolyticum, Aureobacterium barkeri to Microbacterium barkeri, Aureobacterium esteraromaticum to Microbacterium esteraromaticum, Aureobacterium flavescens to Microbacterium flavescens, Aureobacterium keratanolyticum to Microbacterium liquefaciens, Aureobacterium luteolum to Microbacterium luteolum, Aureobacterium saperdae to Microbacterium saperdae, Aureobacterium schleiferi to Microbacterium schleiferi, Aureobacterium terrae to Microbacterium terrae, Aureobacterium terregens to Microbacterium terregens, Aureobacterium testaceum to Microbacterium testaceum, and Aureobacterium trichothecenolyticum to Microbacterium trichothecenolyticum.

Gordonia rhizosphera sp. nov. isolated from the mangrove rhizosphere

The taxonomic position of bacterial strain 141T, isolated from the mangrove rhizosphere, has been clarified by phenotypic, chemotaxonomic and phylogenetic studies. The strain possesses wall chemotype IV, MK-9(H2) as the predominant menaquinone, relatively long-chain mycolic acids (56-64) carbon atoms) and straight-chain saturated and monounsaturated fatty acids with a small amount of tuberculostearic acid. The G+C content of the DNA is 66.8 mol%. Similarity values for genes encoding 16S rRNA indicated that strain 141T represents a new species within the genus Gordonia for which the name Gordonia rhizosphera sp. nov. is proposed. The type strain of G. rhizosphere is 141T (IFO 16068T).

A new genus of the order Actinomycetales, Spirilliplanes gen. nov., with description of Spirilliplanes yamanashiensis sp. nov.

Actinomycete strain YU127-1T (T = type strain), which produces zoospores, was isolated from a soil sample. The aerial mycelium of this organism at maturity forms short chains of spores. The hyphae form coils, and sporangia are not observed. Strain YU127-1T contains glutamic acid, glucosamine, glycine, alanine, and meso-diaminopimelic acid in its cell wall (wall chemotype II), 3-O-methylmannose, mannose, xylose, and glucose as whole-cell sugars, meanaquinone 10(H4), and glycolyl cell wall polysaccharides and has a guanine-plus-cytosine content of 69.0 mol%. Mycolic acids are absent. Phosphatidylinositol and phosphatidylethanolamine are diagnostic phospholipids. The chemotaxonomic data, except for the lack of arabinose in the whole-cell sugars, indicate that this strain belongs to the family Micromonosporaceae. The morphological and physiological characteristics and chemotaxonomic and phylogenetic data for this strain differ from those of the previously described actinomycetes. We therefore propose a new genus, spirilliplanes, for this organism; the type species of the genus is Spirilliplanes yamanashiensis sp. nov., and the type strain of S. yamanashiensis is strain YU127-1 (= IFO 15828).

Acrocarpospora gen. nov., a new genus of the order Actinomycetales

The taxonomic position of two actinomycete strains isolated from soil was studied. The isolates contained glutamic acid, alanine and meso-diaminopimelic acid as cell-wall amino acids and menaquinone MK-9(H4) and madurose in the whole-cell hydrolysate. Phylogenetic analysis revealed that the isolates belonged to the family Streptosporangiaceae, but not to any known genus, and formed a monophyletic cluster with Streptosporangium corrugatum. On the basis of morphological characteristics, phylogenetic analysis and DNA-DNA hybridization, the name Acrocarpospora gen. nov. is proposed for a new genus containing the isolates and Streptosporangium corrugatum, and Acrocarpospora pleiomorpha sp. nov. R-31T (= IFO 16267T), Acrocarpospora macrocephala sp. nov. R-55T (=IFO 16266T) and Acrocarpospora corrugata comb. nov. IFO 13972T are described.

Agromyces luteolus sp. nov., Agromyces rhizospherae sp. nov. and Agromyces bracchium sp. nov., from the mangrove rhizosphere.

The taxonomic positions of four strains isolated from the mangrove rhizosphere were studied by a polyphasic approach using phenotypic, chemotaxonomic and genetic methods. The four isolates contain 2,4-diaminobutyric acid in their peptidoglycan, and rhamnose as the major cell wall sugar. The predominant menaquinones are MK-12 and MK-11. The predominant cellular fatty acids are iso-C16:0, anteiso-C15:0 and/or anteiso-C17:0. The G+C content of the DNA ranges from 70.0 to 73.3 mol%. The four strains formed a coherent cluster with Agromyces species in a phylogenetic inference based on 16S rDNA sequences. Interestingly, the four isolates grew well in the presence of 5% NaCl. The differences in some phenotypic and chemotaxonomic characteristics, 16S rDNA sequence similarity data and DNA-DNA relatedness data indicate that the four isolates represent three new species in the genus Agromyces, for which are proposed the names Agromyces luteolus for strain 8T (IFO 16235T = VKM Ac-2085T), Agromyces bracchium for strain 65T (IFO 16238T = VKM Ac-2088T) and Agromyces rhizospherae for strains 14T (IFO 16236T = VKM Ac-2086T) and 58(5) (IFO 16237 = VKM Ac-2087).

A new genus of the order Actinomycetales, Virgosporangium gen. nov., with descriptions of Virgosporangium ochraceum sp. nov. and Virgosporangium aurantiacum sp. nov.

Four motile spored strains were isolated from soil samples collected in Japan. The cultures formed long, narrow sporangia on short sporangiophores directly on the substrate mycelium. The sporangia develop singly or in clusters above the surface of the substrate. Each sporangium contains a single row of six or more motile spores. Glutamic acid, glucosamine, glycine, alanine and 3-OH-diaminopimelic acid are present in the cell wall; the whole-cell sugars are 3-O-methylmannose, rhamnose, mannose, arabinose, galactose, xylose and glucose; and the predominant menaquinones are 10(H4), 10(H6) and 10(H8). The diagnostic phospholipid is phosphatidylethanolamine. The acyl type of the muramic acid is glycolyl. The G+C content is 71 mol%. Mycolic acids are absent. The chemotaxonomic data indicate that these strains belong to the family Micromonosporaceae. Analysis of 165 rDNA sequences suggested that these organisms fall into a distinct clade within the family Micromonosporaceae for which a new genus, Virgosporangium gen. nov., is proposed containing the species Virgosporangium ochraceum sp. nov. (strains YU655-43T, YU793-41 and YU794-41) and Virgosporangium aurantiacum sp. nov. (strain YU438-5T).

Purification and properties of thermostable N-acylamino acid racemase from Amycolatopsis sp. TS-1-60

Thermostable N-acylamino acid recemase from Amycolatopsis sp. TS-1-60, a rare actinomycete strain selected for its ability to grow on agar plates incubated at 40° C, was purified to homogeneity and characterized. The relative molecular mass (Mr) of the native enzyme and the subunit was estimated to be 300 000 and 40 000 on gel filtration chromatography and sodium dodecyl sulfate-polyacrylamide gel electrophoresis respectively. The isoelectric point (pI) of the enzyme was 4.2. The optimum temperature and pH were 50° C and 7.5 respectively. The enzyme was stable at 55° C for 30 min. The enzyme catalyzed the racemization of optically active N-acylamino acids such as N-acetyl-l-or d-methionine, N-acetyl-l-valine, N-acetyl-l-tyrosine and N-chloroacetyl-l-valine. In addition, the enzyme also catalyzed the recemization of the dipeptide l-alanyl-l-methionine. By contrast, the optically active amino acids, N-alkyl-amino acids and methyl and athyl ester derivatives of N-acetyl-d- and l-methionine were not racemized. The apparent Km values for N-acetyl-l-methionine and N-acetyl-d-methionine were calculated to be 18.5 mM and 11.3 mM respectively. The enzyme activity was markedly enhanced by the addition of divalent metal ions such as Co2+, Mn2+ and Fe2+ and was inhibited by addition of EDTA and P-chloromercuribenzoic acid. The similarity between the NH2-terminal amino acid sequence of the enzyme and that of Streptomyces atratus Y-53 [Tokuyama et al. (1994) Appl Microbiol Biotechnol 40:835–840] was above 80%.

Sporichthya brevicatena sp. nov.

A strain was isolated from soil that formed short chains of aerial mycelium dividing into motile spores on an agar medium, but not substrate mycelium. The organism had menaquinone 9(H8), LL-diaminopimelic acid in the cell wall amino acids and a DNA G + C content of 71 mol%. On the basis of the morphological and chemotaxonomic characteristics and phylogenetic analysis, this strain was classified into the genus Sporichthya. DNA-DNA hybridization revealed that the strain differed from the known species, Sporichthya polymorpha. Therefore, a new species, Sporichthya brevicatena sp. nov., is proposed. The type strain is S. brevicatena YU720-21T (= IFO 16195T).

A new genus of the order Actinomycetales, Cryptosporangium gen. nov., with descriptions of Cryptosporangium arvum sp. nov. and Cryptosporangium japonicum sp. nov.

Four strains that form sporangia with motile sporangiospores and mycelia were isolated from soil samples. Their many sporangia were covered by mycelia. They had glutamic acid, glycine, alanine and meso-diaminopimelic acid as cell wall amino acids (wall chemotype II), acofriose (3-O-mythylrhamnose) as a characteristic whole-cell sugar, and menaquinone 9(H6). The taxonomic characteristics of these strains differ from those of the previously described motile actinomycetes. On the basis of the morphological, physiological, chemotaxonomic and phylogenetic analyses, a new genus is proposed, Cryptosporangium, and two new species, Cryptosporangium arvum sp. nov (type strain IFO 15965T) for strain YU 629-21T and Cryptosporangium japonicum sp. nov (type strain IFO 15966T) for strains YU 636-3T, YU 655-31 and YU 656-31.

A selective isolation method for Actinomadura viridis in soil

Abstract The rare actinomycete Actinomadura viridis was efficiently isolated from a variety of field soils by a new plate culture method in which a water suspension of dry-heated (110°C, 1h) soil was treated with 1.0% phenol and cultured on Humic acid-vitamin agar supplemented with kanamycin, josamycin, lysozyme and nalidixic acid. The method significantly eliminated unicellular bacteria and undesirable actinomycetes contaminants from the isolation plates, thereby achieving the highly selective isolation of A. viridis .