No abstract

, was isolated from a bacterial mat in a Japanese hot spring. Morphologically, the isolate was an unbranched multicellular filament with a cell diameter of 08-10 µm. The bacterium was red to reddish-brown in colour and formed a distinct red bacterial mat in the natural environment. It was able to grow photoheterotrophically under anaerobic light conditions and also chemoheterotrophically under aerobic dark conditions. Optimal growth occurred at 50 SC and pH 75-80. The cells contained bacteriochlorophyll (Bchl) a and γ-carotene derivatives as photosynthetic pigments, but lacked Bchl c and chlorosomes. Cellular fatty acids in the isolate were mainly C16 :0, C14 :0 and C15 :0. The major quinone was menaquinone-11. The DNA GMC content was 620 mol % (by HPLC). Phylogenetic analysis based on 16S rDNA sequencing suggested that the isolate belonged to the anoxygenic filamentous phototrophic bacteria represented by Chloroflexus aurantiacus, but was clearly distant from all members in this group (the sequence similarities between the isolate and its relatives were less than 838 %). Based on genotypic and phenotypic data, the name Roseiflexus castenholzii gen. nov., sp. nov. is proposed for this isolate ; the type strain is HLO8 T (l DSM 13941 T l JCM 11240 T ).

One thermophilic (strain IMO-1T) and two mesophilic (strains KIBI-1T and YMTK-2T) non-spore-forming, non-motile, Gram-negative, multicellular filamentous micro-organisms, which were previously isolated as members of the tentatively named class ‘Anaerolineae’ of the phylum Chloroflexi, were characterized. All isolates were strictly anaerobic micro-organisms. The length of the three filamentous isolates was greater than 100 μm and the width was 0.3–0.4 μm for strain IMO-1T, 0.4–0.5 μm for strain KIBI-1T and thinner than 0.2 μm for strain YMTK-2T. Strain IMO-1T could grow at pH 6.0–7.5 (optimum growth at pH 7.0). The optimal temperature for growth of strain IMO-1T was around 50 °C (growth occurred between 42 and 55 °C). Growth of the mesophilic strains KIBI-1T and YMTK-2T occurred at pH 6.0–7.2 with optimal growth at pH 7.0. Both of the mesophilic strains were able to grow in a temperature range of 25–50 °C with optimal growth at around 37 °C. Yeast extract was required for growth of all three strains. All the strains could grow with a number of carbohydrates in the presence of yeast extract. The G+C contents of the DNA of strains IMO-1T, KIBI-1T and YMTK-2T were respectively 53.3, 59.5 and 48.2 mol%. Major fatty acids for thermophilic strain IMO-1T were anteiso-C17 : 0, iso-C15 : 0, C16 : 0 and anteiso-C15 : 0, whereas those for mesophilic strains KIBI-1T and YMTK-2T were branched C14 : 0, iso-C15 : 0, C16 : 0 and branched C17 : 0, and branched C17 : 0, C16 : 0, C14 : 0 and C17 : 0, respectively. Detailed phylogenetic analyses based on their 16S rRNA gene sequences indicated that the isolates belong to the class-level taxon ‘Anaerolineae’ of the bacterial phylum Chloroflexi, which for a long time had been considered as a typical uncultured clone cluster. Their morphological, physiological, chemotaxonomic and genetic traits strongly support the conclusion that these strains should be described as three novel independent taxa in the phylum Chloroflexi. Here, Anaerolinea thermolimosa sp. nov. (type strain IMO-1T=JCM 12577T=DSM 16554T), Levilinea saccharolytica gen. nov., sp. nov. (type strain KIBI-1T=JCM 12578T=DSM 16555T) and Leptolinea tardivitalis gen. nov., sp. nov. (type strain YMTK-2T=JCM 12579T=DSM 16556T) are proposed. In addition, we formally propose to subdivide the tentative class-level taxon ‘Anaerolineae’ into Anaerolineae classis nov. and Caldilineae classis nov. We also propose the subordinate taxa Anaerolineales ord. nov., Caldilineales ord. nov., Anaerolineaceae fam. nov. and Caldilineaceae fam. nov.

A novel anaerobic, thermophilic, syntrophic acetate-oxidizing bacterium, strain PB T , was isolated from a thermophilic (55 SC) anaerobic methanogenic reactor which had been treating kraft-pulp waste water. The bacterium oxidized acetate in co-culture with a thermophilic hydrogenotrophic methanogen. Strain PB T , a Gram-positive, spore-forming, rod-shaped bacterium grew optimally at 58 SC and pH 68. The bacterium grew acetogenically on several alcohols, methoxylated aromatics, pyruvate, glycine, cysteine, formate and hydrogen/CO 2 . Strain PB T also oxidized acetate with reduction of sulfate or thiosulfate as the electron acceptor. The bacterium contained MK-7 as the major quinone. The GMC content of the DNA was 535 mol %. Comparative 16S rDNA analysis indicated that strain PB T belongs to the Bacillus-Clostridium subphylum. However, it was distant from any known genera or microorganism. The closest known relative was Thermoterrabacterium ferrireducens with 874 % similarity. The name Thermacetogenium phaeum gen. nov., sp. nov. is proposed. The type strain is strain PB T (l DSM 12270 T ).

Comparative analysis of bacterial diversity in freshwater sediment collected from a shallow eutrophic lake was performed by using 16S rRNA gene clone library and improved cultivation-based techniques. Our study demonstrated that the use of gellan gum as a gelling reagent instead of agar was more effective at increasing culturability, cultivating a diverse array of novel microbes, and reducing the gaps of the results between molecular and cultivation-based analyses.