The genus Allochromatium (Chromatiales Chromatiaceae) revisited: a study on its intragenic structure based on multilocus sequence analysis (MLSA) and DNA-DNA hybridization (DDH).

In this study, the taxonomic status of anoxygenic photosynthetic bacteria belonging to the genus Allochromatium is revisited. The inter- and intraspecies relationship of seven Allochromatium strains, including a set of well described type strains, were examined by DNA-DNA hybridization (DDH) and multilocus sequence analysis (MLSA) using segments of seven protein-coding genes. The re-sequencing of the 16S rRNA, the internal transcriber spacer (ITS), multi-gene analysis and DDH comparison indicated that both type strains Allochromatium vinosum DSM 180(T) and Allochromatium minutissimum DSM 1376(T) are closely related to each other forming an independent cluster together with the strains A.

Spirosoma spitsbergense sp. nov. and Spirosoma luteum sp. nov., isolated from a high Arctic permafrost soil, and emended description of the genus Spirosoma.

Two pigmented, Gram-negative, non-motile, pleomorphic rod-shaped bacteria (strains SPM-9(T) and SPM-10(T)) were isolated from a permafrost soil collected from the Adventdalen valley, Spitsbergen, northern Norway. A third isolate (strain M5-H2) was recovered from the same soil sample after the sample had been exposed to simulated Martian environmental conditions. The three strains were characterized taxonomically by using a polyphasic approach.

Demequina lutea sp. nov., isolated from a high Arctic permafrost soil.

Two Gram-stain-positive, pigmented, non-motile, non-spore-forming, pleomorphic, rod-shaped bacteria (strains SV45(T) and SV47), isolated from a permafrost soil collected from the Adventdalen valley, Spitsbergen, northern Norway, have been characterized taxonomically using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the two permafrost isolates formed a distinct phyletic line within the suborder Micrococcineae of the order Actinomycetales. DNA-DNA hybridization analyses indicate that strains SV45(T) and SV47 are closely related (60-69 % relatedness) and belong to the same species, although they show slightly different colony pigmentation.

Viability, diversity and composition of the bacterial community in a high Arctic permafrost soil from Spitsbergen, Northern Norway.

The viable and non-viable fractions of the bacterial community in a 2347-year-old permafrost soil from Spitsbergen were subjected to a comprehensive investigation using culture-independent and culture-dependent methods. LIVE/DEAD BacLight staining revealed that 26% of the total number of bacterial cells were viable. Quantitatively, aerobic microcolonies, aerobic colony-forming units and culturable anaerobic bacteria comprised a minor fraction of the total number of viable bacteria, which underlines the necessity for alternative cultivation approaches in bacterial cryobiology.

Phototrophic purple sulfur bacteria as heat engines in the South Andros Black Hole.

Photosynthetic organisms normally endeavor to optimize the efficiency of their light-harvesting apparatus. However, here we describe two bacterial isolates belonging to the genera Allochromatium and Thiocapsa that demonstrate a novel adaptation by optimizing their external growth conditions at the expense of photosynthetic efficiency. In the South Andros Black Hole, Bahamas, a dense l-m thick layer of these anoxygenic purple sulfur bacteria is present at a depth of 17.

Characterization of purple sulfur bacteria from the South Andros Black Hole cave system: highlights taxonomic problems for ecological studies among the genera Allochromatium and Thiocapsa.

A dense 1 m thick layer of phototrophic purple sulfur bacteria is present at the pycnocline (17.8 m depth) in the meromictic South Andros Black Hole cave system (Bahamas). Two purple sulfur bacteria present in samples collected from this layer have been identified as belonging to the family Chromatiaceae.

Isolation and characterization of spirilloid purple phototrophic bacteria forming red layers in microbial mats of Mediterranean salterns: description of Halorhodospira neutriphila sp. nov. and emendation of the genus Halorhodospira.

Microbial mats developing in the hypersaline lagoons of a commercial saltern in the Salin-de-Giraud (Rhône delta) were found to contain a red layer fully dominated by spirilloid phototrophic purple bacteria underlying a cyanobacterial layer. From this layer four strains of spirilloid purple bacteria were isolated, all of which were extremely halophilic. All strains were isolated by using the same medium under halophilic photolithoheterotrophic conditions.