[Anaerobic bacteria involved in the degradation of aromatic sulfonates to methane]

An anaerobic microbial consortium that degrades benzene- and p-toluenesulfonate to form methane and fatty acids has been produced. Pure cultures of three strains of anaerobic spore-forming bacteria Clostridium spp., as well as the sulfate-reducing bacteria Desulfovibrio sp., were isolated and characterized. Phylogenetic analysis of 16S rRNA gene sequences of strains showed that pure cultures of clostridia strains 14, 24, and 21 are close to Clostridium lituseburense DSM 797T, C. sartagoforme DSM 1292T, and C. pascui DSM 10365T, and the sulfate-reducing strain SR1 is genotypically closer to Desulfovibrio aminophilus ALA-3T. Preliminary characterization of isolated bacteria makes it possible to assume that these are new species of the genera Clostridium and Desulfovibrio, the distinctive feature of which is the ability to incorporate aromatic sulfonates in their metabolisms.

Microbial populations in Antarctic permafrost: biodiversity, state, age, and implication for astrobiology

Antarctic permafrost soils have not received as much geocryological and biological study as has been devoted to the ice sheet, though the permafrost is more stable and older and inhabited by more microbes. This makes these soils potentially more informative and a more significant microbial repository than ice sheets. Due to the stability of the subsurface physicochemical regime, Antarctic permafrost is not an extreme environment but a balanced natural one. Up to 10(4) viable cells/g, whose age presumably corresponds to the longevity of the permanently frozen state of the sediments, have been isolated from Antarctic permafrost. Along with the microbes, metabolic by-products are preserved. This presumed natural cryopreservation makes it possible to observe what may be the oldest microbial communities on Earth. Here, we describe the Antarctic permafrost habitat and biodiversity and provide a model for martian ecosystems.