Desulfosporosinus lacus sp. nov., a sulfate-reducing bacterium isolated from pristine freshwater lake sediments

A novel sulfate-reducing bacterium was isolated from pristine sediments of Lake Stechlin, Germany. This strain, STP12 , was found to contain predominantly c-type cytochromes and to reduce sulfate, sulfite and thiosulfate using lactate as an electron donor. Although STP12 could not utilize elemental sulfur as an electron acceptor, it could support growth by dissimilatory Fe(III) reduction. In a comparison of 16S rRNA gene sequences, STP12 was 96.7 % similar to Desulfosporosinus auripigmenti DSM 13351 , 96.5 % similar to Desulfosporosinus meridiei DSM 13257 and 96.4 % similar to Desulfosporosinus orientis DSM 765 . DNA-DNA hybridization experiments revealed that strain STP12 shows only 32 % reassociation with the type strain of the type species of the genus, D. orientis DSM 765 . These data, considered in conjunction with strain-specific differences in heavy metal tolerance, cell-wall chemotaxonomy and riboprint patterns, support recognition of strain STP12 (=DSM 15449 =JCM 12239 ) as the type strain of a distinct and novel species within the genus Desulfosporosinus, Desulfosporosinus lacus sp. nov. © 2006 IUMS. T T T T T T T T T T

Desulfovibrio idahonensis sp. nov., sulfatereducing bacteria isolated from a metal(loid)-contaminated freshwater sediment

Two novel sulfate-reducing bacteria, strains CY1 and CY2, were isolated from heavy-metal-contaminated sediments of Lake Coeur d\u27Alene, Idaho, USA. Strains CY1 and CY2 were found to contain c-type cytochromes and to reduce sulfate, sulfite, thiosulfate, elemental sulfur, DMSO, anthraquinone disulfonate and fumarate using lactate as an electron donor. In a comparison of 16S rRNA gene sequences, CY1 and CY2 were found to be 100% identical, but only 97 and 92.4% similar, respectively, to the type strains of Desulfovibrio mexicanus and Desulfovibrio aminophilus. Unlike these species, however, CY1 was neither able to disproportionate thiosulfate nor able to use yeast extract or amino acids as electron donors. These data, considered in conjunction with differences among strain CY1 and the two related type strains in chemotaxonomy, riboprint patterns, temperature and pH optima, support recognition of a distinct and novel species within the genus Desulfovibrio, Desulfovibrio idahonensis sp. nov., with the type strain CY1 (=DSM 15450 =JCM 14124 ). © 2009 IUMS. T T T T T T T

Mycobacterium doricum sp. nov.

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Saccharothrix sp. PAL54, a new chloramphenicol-producing strain isolated from a Saharan soil

An actinomycete strain designated PAL54, producing an antibacterial substance, was isolated from a Saharan soil in Ghardaïa, Algeria. Morphological and chemical studies indicated that this strain belonged to the genus Saccharothrix. Analysis of the 16S rDNA sequence showed a similarity level ranging between 96.9 and 99.2% within Saccharothrix species, with S. longispora DSM 43749T, the most closely related. DNA–DNA hybridization confirmed that strain PAL54 belonged to Saccharothrix longispora. It showed very strong activity against pathogenic Gram-positive and Gram-negative bacteria responsible for nosocomial infections and resistant to multiple antibiotics. Strain PAL54 secreted the antibiotic optimally during mid-stationary and decline phases of growth. One antibacterial compound was isolated from the culture broth and purified by HPLC. The active compound was elucidated by uv-visible and NMR spectroscopy and by mass spectrometry. The results showed that this compound was a D(-)-threo chloramphenicol. This is the first report of chloramphenicol production by a Saccharothrix species

Biosynthesis of iso-fatty acids in myxobacteria

The fatty acid (FA) profiles of the myxobacteria Stigmatella aurantiaca and Myxococcus xanthus were investigated by acidic methanolysis of total cell extracts and GC or GC-MS analysis. The main components were 13-methyltetradecanoic acid (iso-15:0) and (Z)-hexadec-11-enoic acid ( 16: 1, omega-5 cis). The biosynthesis of iso-FAs was investigated in several feeding experiments. Feeding of isovaleric acid (IVA) to a mutant impaired in the degradation of leucine to isovaleryl-CoA (IV-CoA) (bkd mutant) of M. xanthus only increased the amount of iso-odd FAs, whereas feeding of isobutyric acid ( IBA) gave increased amounts only of iso-even FAs. In contrast, a bkd mutant of S. aurantiaca gave increased amounts of iso-odd and iso-even fatty acids in both experiments. We assumed that in S. aurantiaca alpha-oxidation takes place. [D-7]-15-Methylhexadecanoic acid ( 8) was synthesised and fed to S. aurantiaca as well as [D-10] leucine and [D-8] valine to elucidate this pathway in more detail. The iso- fatty acid 8 was degraded by alpha- and beta-oxidation steps. [D-10] Leucine was strongly incorporated into iso-odd and iso-even fatty acids, whereas the incorporation rates for [D-8] valine into both types of fatty acids were low. Thus alpha-oxidation plays an important role in the biosynthesis of iso-fatty acids in S. aurantiaca. The incorporation rates observed after feeding of [D-10] leucine and [D-8] valine are the highest for iso-17: 0 compared to the other acids. This indicates the central role of iso-17 : 0 in the biosynthesis of iso-FAs. The shorter homologues seem to be formed mainly by alpha-oxidation and beta-oxidation of this acid. After feeding of 8 traces of unsaturated counterparts of this labelled FA occurred in the extracts indicating that desaturases are active in the biosynthesis of unsaturated fatty acids in S. aurantiaca

Evidence for the phylogenetic heterogeneity of the genus Streptosporangium

Comparative 16S rDNA/RNA analyses of five of the fifteen described species of the actinomycete genus Streptosporangium indicate the phylogenetic heterogeneity of the genus. The type species Streptosporangium roseum, Streptosporangium nondiastaticum and Streptosporangium pseudovulgare form a highly related cluster, while Streptosporangium corrugatum is more distantly related. Within the radiation of actinomycete genera these four organisms branch as a sistergroup to the genus Streptomyces. Streptosporangium viridogriseum subsp. viridogriseum was phylogenetically placed within the radiation of the family Pseudonocardiaceae were it branched adjacent to Saccharothrix australiensis. The results confirm previous findings on the heterogeneity of the genus wich were based on scanning electon microscopy (Nonomura, 1989) and the electrophoretic mobility of a ribosomal protein (Ochi and Miyadoh, 1992