Structure elucidation and gene cluster annotation of the O-antigen of Halomonas titanicae TAT1 containing three residues of 2,3-diacetamido-2,3-dideoxy-D-glucuronic acid.

A halotolerant hydrocarbon-oxidizing bacterium Halomonas titanicae strain TAT1 was isolated from a petroleum reservoir. The O-polysaccharide (O-antigen) was isolated from the lipopolysaccharide of H. titanicae TAT1 and studied by component analyses and 1D and 2D NMR spectroscopy. The following structure of the repeating linear pentasaccharide O-unit, containing only aminosugars, was established: →4)-ß-d-GlcpNAc3NAcA-(1 â†’ 4)-ß-d-GlcpNAc3NAcA-(1 â†’ 6)-α-d-GlcpNAc-(1 â†’ 4)-ß-d-GlcpNAc3NAcA-(1 â†’ 6)-α-d-GlcpNAc-(→, where d-GlcNAc3NAcA indicates 2,3-diacetamido-2,3-dideoxy-d-glucuronic acid. The O-antigen gene cluster was identified in the genome of H. titanicae TAT1 and compared with available database sequences. The genes revealed in the O-antigen gene cluster and the assigned functions of putative proteins were consistent with the established polysaccharide structure.

Ecology and biogeography of the 'marine Geitlerinema' cluster and a description of Sodalinema orleanskyi sp. nov., Sodalinema gerasimenkoae sp. nov., Sodalinema stali sp. nov. and Baaleninema simplex gen. et sp. nov. (Oscillatoriales, Cyanobacteria).

Filamentous cyanobacteria belonging to the 'marine Geitlerinema' cluster are spread worldwide in saline environments and considered to play an important ecological role. However, the taxonomy of this group remains unclear. Here, we analyzed the phylogeny, ecology and biogeography of the 'marine Geitlerinema' cluster representatives and revealed two subclusters: (1) an 'oceanic' subcluster containing PCC7105 clade and black band disease (BBD) clade with free-living and pathogenic strains distributed in Atlantic, Indian and Pacific Ocean-related localities, and (2) a Sodalinema subcluster containing free-living strains from marine, hypersaline, saline-alkaline and soda lake habitats from the Eurasian and African continents. Polyphasic analysis using genetic and phenotypic criteria demonstrated that these two groups represent separate genera. Representatives of Sodalinema subcluster were phylogenetically attributed to the genus Sodalinema. Our data expand the ecological and geographical distribution of this genus. We emended the description of the genus Sodalinema and proposed three new species differing in phylogenetic, geographic and ecological criteria: Sodalinema orleanskyi sp. nov., Sodalinema gerasimenkoae sp. nov. and Sodalinema stali sp. nov. Additionally, a new genus and species Baaleninema simplex gen. et sp. nov. was discribed within the PCC7105 clade. By this, we put in order the current confusion of the 'marine Geitlerinema' group and highlight its ecological diversity.

Diversity of Metabolically Active Bacteria in Water-Flooded High-Temperature Heavy Oil Reservoir.

The goal of this work was to study the overall genomic diversity of microorganisms of the Dagang high-temperature oilfield (PRC) and to characterize the metabolically active fraction of these populations. At this water-flooded oilfield, the microbial community of formation water from the near-bottom zone of an injection well where the most active microbial processes of oil degradation occur was investigated using molecular, cultural, radiotracer, and physicochemical techniques. The samples of microbial DNA and RNA from back-flushed water were used to obtain the clone libraries for the 16S rRNA gene and cDNA of 16S rRNA, respectively. The DNA-derived clone libraries were found to contain bacterial and archaeal 16S rRNA genes and the alkB genes encoding alkane monooxygenases similar to those encoded by alkB-geo1 and alkB-geo6 of geobacilli. The 16S rRNA genes of methanogens (Methanomethylovorans, Methanoculleus, Methanolinea, Methanothrix, and Methanocalculus) were predominant in the DNA-derived library of Archaea cloned sequences; among the bacterial sequences, the 16S rRNA genes of members of the genus Geobacillus were the most numerous. The RNA-derived library contained only bacterial cDNA of the 16S rRNA sequences belonging to metabolically active aerobic organotrophic bacteria (Tepidimonas, Pseudomonas, Acinetobacter), as well as of denitrifying (Azoarcus, Tepidiphilus, Calditerrivibrio), fermenting (Bellilinea), iron-reducing (Geobacter), and sulfate- and sulfur-reducing bacteria (Desulfomicrobium, Desulfuromonas). The presence of the microorganisms of the main functional groups revealed by molecular techniques was confirmed by the results of cultural, radioisotope, and geochemical research. Functioning of the mesophilic and thermophilic branches was shown for the microbial food chain of the near-bottom zone of the injection well, which included the microorganisms of the carbon, sulfur, iron, and nitrogen cycles.

Proposal of Spirillum winogradskyi sp. nov., a novel microaerophilic species, an emended description of the genus Spirillum and Request for an Opinion regarding the status of the species Spirillum volutans Ehrenberg 1832.

A novel obligately organotrophic, facultatively microaerophilic spirillum, designated strain D-427(T), was isolated from sulfidic sludge of a municipal wastewater-treatment plant. Cells were Gram-negative, large and highly motile due to bipolar tufts of flagella covered with mucous sheaths. Coccoid cells were sometimes formed. Strain D-427(T) grew optimally at pH 7.5-7.8 and 28 degrees C in the presence of 2 % O(2) in the gas phase. The organism showed oxidase and very low catalase activity. The isolate grew chemo-organotrophically with a limited number of organic acids as substrates. The DNA G+C content was 38.0 mol% (T(m)). Phylogenetic analysis of the 16S rRNA gene sequence placed strain D-427(T) in the genus Spirillum within the class Betaproteobacteria. The 16S rRNA gene sequence similarity between strain D-427(T) and Spirillum volutans ATCC 19554(T), the type strain of the single species of the genus, was 98.6 %. The low level of DNA-DNA hybridization and different phenotypic properties indicate that strain D-427(T) is clearly distinguishable from Spirillum volutans. No strain of S. volutans is available from any established culture collection or from the authors who described this species. Therefore, on the basis of phenotypic and genotypic data and the fact that the type and single species of the genus Spirillum cannot be included in any scientific study, since the type strain has been lost, we propose to assign strain D-427(T) as a novel species of the genus Spirillum, Spirillum winogradskyi sp. nov. (type strain D-427(T) =DSM 12756(T) =VKM B-2518(T)), and we request that the Judicial Commission place the name Spirillum volutans on the list of rejected names if a suitable type strain is not found or a neotype is not proposed within 2 years following the publication of this paper. An emended description of the genus Spirillum is also provided.

Novel facultative anaerobic acidotolerant Telmatospirillum siberiense gen. nov. sp. nov. isolated from mesotrophic fen.

Three facultative anaerobic acidotolerant Gram-negative motile spirilla strains designated 26-4b1, 26-2 and K-1 were isolated from mesotrophic Siberian fen as a component of methanogenic consortia. The isolates were found to grow chemoorganotrophically on several organic acids and glucose under anoxic and low oxygen pressure in the dark, tolerant up to 5kPa of oxygen. At low oxygen supply, faint autotrophic growth on the H(2):CO(2) mixture was also observed. All three isolates were able to fix N(2). Major cellular fatty acids were 18:1 omega7c, 17:0 cyclopropane and 16:0. Phylogenetic analyses of the 16S rRNA gene sequences revealed that they formed a deep branch within the family Rhodospirillaceae of the Alphaproteobacteria with the highest similarity of 90.9-92.5% with members of genera Phaeospirillum and Magnetospirillum. Phylogenetic study of nifH (nitrogenase) and cbbL (RuBisCO) amino acid sequence identities confirmed that the new isolates represent a novel group. Based on the phylogenetic analyses and distinct phenotypic characteristics, we are of the opinion that strains 26-4b1, 26-2 and K-1 represent a new species of a novel genus for which the name Telmatospirillum siberiense gen. nov. sp. nov. is proposed.

Isolation and characterization of oligotrophic acido-tolerant methanogenic consortia from a Sphagnum peat bog.

Two dense and highly enriched (up to 10(9) cells ml(-1), <10% of bacterial satellites) acido-tolerant (pH 4.0-6.5) methanogenic consortia, '26' and 'K', were isolated from the peat beneath a Sphagnum-Eriophorum-Carex community in West Siberia. Both consortia produced methane from CO2:H2 on chemically defined, diluted N-free media containing Ti(III)citrate as reducing agent. The phylogenetic analysis of 16S ribosomal DNA revealed three archaeal and nine bacterial sequence types. Consortium '26' contained single archaea Methanobacterium sp., represented by rods of 1.5-10x0.5-1.0 microm. In consortium 'K', there were two archaeal phylotypes, the respective methanogens were further differentiated morphologically with the fluorescence in situ hybridization technique: one less abundant (<2%) population of the long-curved rods (50-100x0.3-0.4 microm) fell into the order of Methanomicrobiales, while the dominant organism ( approximately 98%), represented by straight rods with abrupt rectangular ends (3-9x0.5 microm), was affiliated with earlier uncultured 'Rice cluster I'. The main bacterial satellite used citrate as a single carbon and energy source; it was similar in both consortia, and after isolation in pure culture, it was identified as a new member of the alpha-subclass of Proteobacteria. The other bacterial satellites were distributed among four taxonomic groups: the delta-subclass of Proteobacteria, the Flavobacterium-Bacteroides-Cytophaga line of descent, the Acidobacterium-Fibrobacter line of descent and the Green non-sulfur bacteria line of descent. At least 11 out of 12 components of acido-tolerant consortia are new to science at the species, genus and order levels; their existence until now was evident only from environmental gene retrievals. The Sphagnum wetlands, attracting attention only recently because of their global environmental role, are shown to be an especially valuable source of novel prokaryotic organisms.

Molecular identification of alkaliphilic and halotolerant strain Bacillus sp. FTU as Bacillus pseudofirmus FTU.

The systematic position of the alkaliphilic and halotolerant strain Bacillus sp. FTU was refined in view of the comprehensive taxonomic revision of the group of alkaliphilic and alkalitolerant Bacillus strains. Sequence analysis of almost the entire 16S rRNA gene of Bacillus sp. FTU revealed 99.8% homology with two Bacillus pseudofirmus strains. Subsequent DNA-DNA hybridization analysis confirmed the close relationship of Bacillus sp. FTU with the type strain of B. pseudofirmus (the level of homology reached 86%). Results of physiological and biochemical characterizations relevant for the group clearly underlined the positioning of strain FTU within this species. It is therefore concluded that Bacillus sp. FTU represents a strain of the alkaliphilic species B. pseudofirmus and is to be renamed as B. pseudofirmus FTU. The phylogeny of different Bacillus species is discussed using N-terminal sequence homologies of some caa (3)-type oxidase subunits.