The central questions of bacterial ecology and evolution require a method to consistently demarcate, from the vast and diverse set of bacterial cells within a natural community, the groups playing ecologically distinct roles (ecotypes). Because of a lack of theorybased guidelines, current methods in bacterial systematics fail to divide the bacterial domain of life into meaningful units of ecology and evolution. We introduce a sequence-based approach (''ecotype simulation'') to model the evolutionary dynamics of bacterial populations and to identify ecotypes within a natural community, focusing here on two Bacillus clades surveyed from the ''Evolution Canyons'' of Israel. This approach has identified multiple ecotypes within traditional species, with each predicted to be an ecologically distinct lineage; many such ecotypes were confirmed to be ecologically distinct, with specialization to different canyon slopes with different solar exposures. Ecotype simulation provides a longneeded natural foundation for microbial ecology and systematics.

Currently, there is no consensus concerning the geographic distribution and extent of endemism in Antarctic cyanobacteria. In this paper we describe the phenotypic and genotypic diversity of cyanobacteria in a field microbial mat sample from Lake Fryxell and in an artificial cold-adapted sample cultured in a benthic gradient chamber (BGC) by using an inoculum from the same mat. Light microscopy and molecular tools, including 16S rRNA gene clone libraries, denaturing gradient gel electrophoresis, and sequencing, were used. For the first time in the study of cyanobacterial diversity of environmental samples, internal transcribed spacer (ITS) sequences were retrieved and analyzed to complement the information obtained from the 16S rRNA gene. Microscopy allowed eight morphotypes to be identified, only one of which is likely to be an Antarctic endemic morphotype. Molecular analysis, however, revealed an entirely different pattern. A much higher number of phylotypes (15 phylotypes) was found, but no sequences from Nodularia and Hydrocoryne, as observed by microscopy, were retrieved. The 16S rRNA gene sequences determined in this study were distributed in 11 phylogenetic lineages, 3 of which were exclusively Antarctic and 2 of which were novel. Collectively, these Antarctic sequences together with all the other polar sequences were distributed in 22 lineages, 9 of which were exclusively Antarctic, including the 2 novel lineages observed in this study. The cultured BGC mat had lower diversity than the field mat. However, the two samples shared three morphotypes and three phylotypes. Moreover, the BGC mat allowed enrichment of one additional phylotype. ITS sequence analysis revealed a complex signal that was difficult to interpret. Finally, this study provided evidence of molecular diversity of cyanobacteria in Antarctica that is much greater than the diversity currently known based on traditional microscopic analysis. Furthermore, Antarctic endemic species were more abundant than was estimated on the basis of morphological features. Decisive arguments concerning the global geographic distribution of cyanobacteria should therefore incorporate data obtained with the molecular tools described here.

The prokaryotic diversity of aerobic and anaerobic bacterial isolates and of bacterial and archaeal 16S rDNA clones was determined for a microbial mat sample from the moated region of Lake Fryxell, McMurdo Dry Valleys, Antarctica. Among the anaerobic bacteria, members of Clostridium estertheticum and some other psychrotolerant strains dominated whereas methanogens and other Archaea were lacking. Isolates highly related to Flavobacterium hibernum, Janthiniobacterium lividum, and Arthrobacter flavus were among the aerobic bacteria most frequently isolated. Assessment of more than 350 partial 16S rDNA clone sequences of libraries generated by Bacteria- and Archaea-specific PCR primers revealed a rich spectrum of bacterial diversity but only two different archaeal clone sequences. Among the Bacteria, representative sequences belonged to the class Proteobacteria, order Verrucomicrobiales, class Actinobacteria, Clostridium/Bacillus subphylum of Gram-positives, and the Cytophaga-Flavobacterium-Bacteroides phylum. The clones formed about 70 higher taxonomy groups (<98% sequence similarity) and 133 potential species, i.e., groups of clones sharing greater than 98% similarity. Only rarely were clone sequences found to be highly related to Lake Fryxell isolates and to strains of described species. Subsequent analysis of ten sequencing batches of 36 individual clones indicated that the diversity might be still higher than had been assessed.

Odoribacter splanchnicus (Werner et al. 1975) Hardham et al. 2008 is the type species of the genus Odoribacter, which belongs to the family Porphyromonadaceae in the order ‘Bacteroidales’. The species is of interest because members of the Odoribacter form an isolated cluster within the Porphyromonadaceae. This is the first completed genome sequence of a member of the genus Odoribacter and the fourth sequence from the family Porphyromonadaceae. The 4,392,288 bp long genome with its 3,672 protein-coding and 74 RNA genes and is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

Spirochaeta coccoides Dröge et al. 2006 is a member of the genus Spirochaeta Ehrenberg 1835, one of the oldest named genera within the Bacteria. S. coccoides is an obligately anaerobic, Gram-negative, non-motile, spherical bacterium that was isolated from the hindgut contents of the termite Neotermes castaneus. The species is of interest because it may play an important role in the digestion of breakdown products from cellulose and hemicellulose in the termite gut. Here we provide a taxonomic re-evaluation for strain SPN1T, and based on physiological and genomic characteristics, we propose its reclassification as a novel species in the genus Sphaerochaeta, a recently published sister group of the Spirochaeta. The 2,227,296 bp long genome of strain SPN1T with its 1,866 protein-coding and 58 RNA genes is a part of the Genomic Encyclopedia of Bacteria and Archaea project.

g Desulfosporosinus species are sulfate-reducing bacteria belonging to the Firmicutes. Their genomes will give insights into the genetic repertoire and evolution of sulfate reducers typically thriving in terrestrial environments and able to degrade toluene (Desulfosporosinus youngiae), to reduce Fe(III) (Desulfosporosinus meridiei, Desulfosporosinus orientis), and to grow under acidic conditions (Desulfosporosinus acidiphilus).T he sequenced Desulfosporosinus type strains (2,3,14,20) represent four out of eight described species belonging to the genus Desulfosporosinus and cover its phylogenetic and physiological breadth. Besides their ability to reduce sulfate for energy conservation, some Desulfosporosinus species can also grow by using nitrate, Fe(III), or As(V) as terminal electron acceptors or by fermentative processes. They can utilize a wide spectrum of energy sources, ranging from aromatic compounds to short-chained fatty acids. A characteristic feature of many Desulfosporosinus species, distinguishing them from their closest sulfate-reducing relatives of the genus Desulfotomaculum, is their ability to grow chemolithoautotrophically on hydrogen (3,14,15,19,(21)(22)(23). Members of the genus Desulfosporosinus are found in low-sulfate freshwater and soil environments but also in sulfate-rich heavymetal-contaminated environments, such as acid mine/rock drainage sites. In addition, Desulfosporosinus species are often observed in low-pH habitats (1, 3, 5-7, 12, 13, 17, 18), with the sequenced Desulfosporosinus acidiphilus strain being the first validly described sulfate-reducing acidophile (3).Genomic DNA was isolated using the Jetflex genomic DNA purification kit (GENOMED, Löhne, Germany) and subjected to sequencing using a combination of 454 Titanium (16) and Illumina (4) technologies. Sequences were assembled with Newbler (version 2.3-PreRelease-6/30/2009) and Velvet (version 1.0.13) (24) for 454 and Illumina data, respectively. Consensus sequences were obtained using computationally shredded Illumina and 454 reads together with 454 paired-end data using parallel Phrap (version SPS-4.24; High Performance Software, LLC). Identification of sequencing errors and improvement of consensus quality were done with Polisher (A. Lapidus, unpublished data) using Illumina data. GapResolution (C. Han, unpublished data), Dupfinisher (11), or sequencing cloned bridging PCR fragments with subcloning were used to correct misassemblies. Gaps between contigs were closed by editing in Consed (8-10), by PCR, and by Bubble PCR (J.-F. Cheng, unpublished data) primer walks. Automated genome annotation was performed at the Oak Ridge National Laboratory and is available at http://genome.ornl.gov/.The circular chromosomes of Desulfosporosinus orientis, Desulfosporosinus youngiae, Desulfosporosinus meridiei, and D. acidiphilus have sizes of 5,863,081 bp, 5,660,978 bp, 4,873,567 bp, and 4,926,837 bp, respectively. The genome of D. acidiphilus additionally harbors two plasmids of 60,447 bp and 3,897 bp. The genomes, in the order listed...

Bacterial strain BF36T, isolated from the biofilm of a tufa deposit in a hard water rivulet, was characterized by a polyphasic taxonomic approach. Cells of these organisms were Gram-negative, motile, nonpigmented, rod-shaped, non-endospore-forming, and facultatively anaerobic. Cells, organized in loose consortia, were coated by a massive slime layer. Phylogenetic analyses using 16S rRNA gene sequences showed that strain BF36T was a member of the family Enterobacteriaceae, class Gammaproteobacteria, displaying a moderate degree of relationship (96.5% sequence similarity) to Sodalis glossinidius and "Sodalis pallipedes," intracellular symbionts of the tsetse fly Glossinis morsitans morsitans. Dendrograms of relationship generated by different algorithms consistently grouped isolate BF36T with Sodalis glossinidius, Pragia fontium, Budvicia aquatica, Serratia rubideae, and Brenneria spp (94.7-95.8% similarity) which also share many common metabolic properties. Differences between strain BF36T and Sodalis glossinidius DSM 13495T are seen in motility and in the pattern of substrates utilized. Membership to the family was also confirmed by a fatty acid profile consisting of major amounts of C16:0)and C16:1omega7, by the presence of isoprenoids of the ubiquinone Q8 and menaquinone MK8 types and a DNA G + C content of 54.2 mol%. The decision to classify strain BF36T into a new genus Biostraticola gen. nov. is based on its distant phylogenetic position as compared to any other representative of the family and the significant phenotypic differences to its nearest phylogenetic neighbor, Sodalis glossinidius. BF36T represents the type species, for which the name Biostraticola tofi sp. nov. is proposed. The type strain is BF36T (DSM 19580T; CIP109699T).

Two freshwater isolates (WB4.1-19 T and WB4.4-101), sharing 99.9 % 16S rRNA gene sequence similarity, were highly related to Aeromonas sobria (99.7 % similarity; 6 bp differences). A phylogenetic tree derived from a multi-locus phylogenetic analysis (MLPA) of the concatenated sequences of five housekeeping genes (gyrB, rpoD, recA, dnaJ and gyrA; 3684 bp) revealed that both strains clustered as an independent phylogenetic line next to members of Aeromonas molluscorum and Aeromonas bivalvium. The DNA-DNA reassociation value between the two new isolates was 89.3 %. Strain WB4.1-19 T had a DNA-DNA relatedness value of ,70 % with the type strains of the other species tested. Phenotypic characterization differentiated the two novel strains from all other type strains of species of the genus Aeromonas. It is concluded that the two new strains represent a novel species of the genus Aeromonas, for which the name Aeromonas rivuli sp. nov. is proposed, with the type strain WB4