Reclassification of Myxococcus flavescens Yamanaka et al. 1990VP as a later synonym of Myxococcus virescens Thaxter 1892AL.

The taxonomic relatedness between the species Myxococcus flavescens and Myxococcus virescens was investigated. Literature data had already indicated the synonymy between the two species but this observation had not been formalized. Additional evidence that the two taxa represent a single species was provided by comparison of metabolic properties, cellular fatty acid profiles and from a DNA-DNA reassociation value of >80 %. Data from this study led to the proposal that M. flavescens should be reclassified as a later synonym of M. virescens.

Taxonomic characterization of members of the genus Corallococcus: molecular divergence versus phenotypic coherency.

Corallococcus coralloides DSM 2259(T), Corallococcus exiguus DSM 14696(T), Corallococcus macrosporus DSM 14697(T) and more than 35 strains identified as members of Corallococcus on the basis of morphology were subjected to partial sequences analysis of three housekeeping genes (lepA, fusA and rpoB), complementing a recent phylogenetic analysis based on genes coding for 16S rRNA and gyrB. Phylogenetic analysis of each gene, generated by maximum likelihood and two different additive treeing algorithms, resulted in the separate position of C. macrosporus DSM 14697(T) and a few Corallococcus strains that were more closely related to Myxococcus xanthus than to the other members of Corallococcus. The latter strains formed three clearly separate clusters by 16S rRNA gene phylogeny. This relationship, however, was only partially recovered by the other gene trees. Group 1, embracing the type strains of C. coralloides and C. exiguus, only emerged as a coherent cluster in the 16S rRNA gene tree. In all other gene trees this cluster embraced organisms of cluster 3, which either formed coherent subclusters (gyrB, lepA) or which appeared polyphyletic (fusA, rpoB). Group 2 organisms consistently constituted a monophyletic cluster, though their branching within the gene trees differed. A concatenated tree, based on the analysis of about 5400 nucleotides of all five partial genes was most similar to the 16S rRNA gene tree. In order to determine whether the individual clusters that emerged by 16S rRNA gene analysis (>99.1% intracluster similarities) show phenetic properties that would allow their description as new species, a few strains of each group were subjected to the analysis of whole cell fatty acid and physiological properties. Riboprint patterns were generated for some members of group 1. While the DNA-DNA reassociation values and riboprint patterns confirmed the genomic heterogeneity of members of cluster 1, none of the other properties investigated were sufficiently discriminative to allow the formal description of strain clusters as new species.

Providencia vermicola sp. nov., isolated from infective juveniles of the entomopathogenic nematode Steinernema thermophilum.

In the course of isolating bacteria from infective juveniles of the entomopathogenic nematode Steinernema thermophilum Ganguly & Singh, 2000, three isolates were obtained (OP1T, OP29 and VS3). On the basis of 16S rRNA gene sequence analysis and riboprint patterns, these three strains were identical to each other but distinct from the type strains of the five recognized species of the genus Providencia. Based on biochemical and genomic analysis and supported by the low (<35 %) DNA-DNA relatedness between strain OP1T and the type strain of its phylogenetically closest relative, Providencia rettgeri (99.5 % 16S rRNA gene sequence similarity), strain OP1T was considered to be sufficiently distinct from recognized Providencia species to warrant the description of a novel species. The name Providencia vermicola sp. nov. is proposed, with OP1T (= DSM 17385T = CIP 108829T) as the type strain.

Molecular detection and isolation of facultatively methylotrophic bacteria, including Methylobacterium podarium sp. nov., from the human foot microflora.

This is the first study to demonstrate that diverse methylotrophic bacteria occur in the human foot microflora. Polymerase chain reaction (PCR) amplification of DNA from the soles and toe clefts of feet of five subjects indicated Methylobacterium strains to be present in all cases. Polymerase chain reaction amplification also showed the gene for the alpha-subunit of methanol dehydrogenase (mxaF) to be present in all samples. Two types of mxaF were recovered, one closest to that of Methylobacterium extorquens and the other most similar to that of Hyphomicrobium methylovorum. Numerous methylotrophic strains able to grow on methylamine were isolated with ease from the feet of nine volunteers. These were found by 16S rRNA analysis to be most closely related to Methylobacterium species, Brevibacterium casei, Pseudomonas strain NZ099 and P. migulae. Three strains from two subjects were of a novel species, Methylobacterium podarium sp. nov. This facultatively methylotrophic, obligately aerobic, pink-pigmented, non-motile rod grew with a wide range of multicarbon and one-carbon compounds including citrate, xylose, mono-, di-, and trimethylamine, dimethylsulphide, methanethiol, dimethylsulphoxide, dimethylsulphone and methanol.

Amycolatopsis decaplanina sp. nov., a novel member of the genus with unusual morphology.

Strain DSM 44594T, which produces the glycopeptide antibiotic decaplanin, is a member of the genus Amycolatopsis based on 16S rRNA gene sequence analysis and chemotaxonomic properties. It is the first member of this genus that is reported to form pseudosporangia, which resemble those of members of the genus Kibdelosporangium. Phylogenetically, the novel taxon is related to Amycolatopsis orientalis, Amycolatopsis lurida, Amycolatopsis azurea, Amycolatopsis japonica and Amycolatopsis keratiniphila. Morphological, cultural and physiological properties, the production of a unique glycolipid and DNA-DNA similarity of <55% with phylogenetically related strains reveal that strain DSM 44594T represents a novel species of the genus, for which the name Amycolatopsis decaplanina sp. nov. (type strain, FH 1845T=DSM 44594T=NRRL B-24209T) is proposed.

Exiguobacterium undae sp. nov. and Exiguobacterium antarcticum sp. nov.

Four orange-pigmented strains from pond water (L1-L4) have been subjected to polyphasic taxonomic analyses. On the basis of ribotype analysis and Fourier-transform infrared spectroscopy, these strains form a genomically highly related group. 16S rDNA sequence analysis revealed 98.8% similarity between the 16S rDNA sequences of strains L2T and H2T, isolated previously from a microbial mat from Lake Fryxell, Antarctica. DNA-DNA reassociation values indicated the presence of two genomic clusters. While the DNA of strains L2T and L3 showed 100% DNA relatedness, strains L2T and H2T shared only 51% DNA relatedness. These two clusters differed in some phenotypic properties, e.g. utilization of melibiose, D-mannitol, adenosine 5'-monophosphate and uridine 5'-monophosphate, and in their fatty acid compositions. Based on the composition of isoprenoid quinones, peptidoglycan, polar lipids and fatty acids, these organisms are members of the genus Exiguobacterium. This is supported by 16S rDNA analyses, which revealed 97-98% similarity to Exiguobacterium acetylicum DSM 20416T and 93.2-93.8% similarity to Exiguobacterium aurantiacum DSM 6208T. E. acetylicum DSM 20416T, the closest phylogenetic neighbour, shows only 39% DNA similarity to strain L2T and 40% DNA similarity to strain H2T. Based on genomic distinctiveness and the clear differences in chemotaxonomy and physiology, two novel species are proposed, Exiguobacterium undae sp. nov. and Exiguobacterium antarcticum sp. nov.