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This study is the first demonstration that a diverse facultatively methylotrophic microbiota exists in some Antarctic locations. PCR amplification of genes diagnostic for methylotrophs was carried out with bacterial DNA isolated from 14 soil and sediment samples from ten locations on Signy Island, South Orkney Islands, Antarctica. Genes encoding the mxaF of methanol dehydrogenase, the fdxA for Afipia ferredoxin, the msmA of methanesulfonate monooxygenase, and the 16S rRNA gene of Methylobacterium were detected in all samples tested. The mxaF gene sequences corresponded to those of Hyphomicrobium, Methylobacterium, and Methylomonas. Over 30 pure cultures of methylotrophs were isolated on methanesulfonate, dimethylsulfone, or dimethylsulfide from ten Signy Island lakes. Some were identified from 16S rRNA gene sequences (and morphology) as Hyphomicrobium species, strains of Afipia felis, and a methylotrophic Flavobacterium strain. Antarctic environments thus contain diverse methylotrophic bacteria, growing on various C1-substrates, including C1-sulfur compounds.

For preliminary screening of human impact on Antarctic coasts, the compositions of microbial communities were analyzed in seawater at two sites located in the Terra Nova Bay of Antarctica (Ross Sea) by a combination of 16S rRNA gene sequencing and culture techniques. The bacterial community in the sample from the Rod Bay site, located at the proximity to the Italian Station, was characterized by a high abundance of 16S rRNA gene sequences belonging to the microflora typically found in soil and freshwater environments. In contrast, the seawater sample from the Adelie Cove station, a pristine reference site, contained 16S rRNA gene sequences typically found in marine areas affected by algal blooms and sea ice decay. The addition of crude oil to the Rod Bay seawater sample rapidly induced a shift in the composition of the bacterial community with appearance of novel taxonomic groups and a dramatic increase in the relative abundance of gamma-Proteobacteria sequences, whereas no significant changes were detected in the bacterial community of the Adelie Cove sample under the same conditions. Bacteria-exhibiting features with potential interest for industrial and environmental applications were isolated from the Rod Bay oil-enriched sample. In particular, hydrocarbon-degrading, cold-adapted bacteria were selectively enriched, isolated and screened for their ability to synthesize polyunsaturated fatty acids. Twenty two bacterial strains were isolated from the oil enrichment culture and identified. Eighteen isolates were found to be members of gamma-Proteobacteria, while the remainder were representatives of alpha-Proteobacteria, CFB and high G + C divisions.

In the McMurdo Dry Valleys of Antarctica, microorganisms colonize the pore spaces of exposed rocks and are thereby protected from the desiccating environmental conditions on the surface. These cryptoendolithic communities have received attention in microscopy and culture-based studies but have not been examined by molecular approaches. We surveyed the microbial biodiversity of selected cryptoendolithic communities by analyzing clone libraries of rRNA genes amplified from environmental DNA. Over 1,100 individual clones from two types of cryptoendolithic communities, cyanobacterium dominated and lichen dominated, were analyzed. Clones fell into 51 relatedness groups (phylotypes) with > or =98% rRNA sequence identity (46 bacterial and 5 eucaryal). No representatives of Archaea were detected. No phylotypes were shared between the two classes of endolithic communities studied. Clone libraries based on both types of communities were dominated by a relatively small number of phylotypes that, because of their relative abundance, presumably represent the main primary producers in these communities. In the lichen-dominated community, three rRNA sequences, from a fungus, a green alga, and a chloroplast, of the types known to be associated with lichens, accounted for over 70% of the clones. This high abundance confirms the dominance of lichens in this community. In contrast, analysis of the supposedly cyanobacterium-dominated community indicated, in addition to cyanobacteria, at least two unsuspected organisms that, because of their abundance, may play important roles in the community. These included a member of the alpha subdivision of the Proteobacteria that potentially is capable of aerobic anoxygenic photosynthesis and a distant relative of Deinococcus that defines, along with other Deinococcus-related sequences from Antarctica, a new clade within the Thermus-Deinococcus bacterial phylogenetic division.