Cyanobacteria in Hypolithic Horizons of Soils in the Larsemann Hills Oasis, East Antarctica

The research is devoted to the analysis of biodiversity of Antarctic cyanobacteria in hypolithic organic-accumulative horizons of soils in the Larsemann Hills oasis. Studies of fouling glasses by the methods of light and confocal microscopy, as well as by fluorescent in situ hybridization, indicate that filamentous forms predominate among cyanobacteria in the upper layers of Antarctic hypolithic microbial communities. Strains of the genera Nostoc, Halotia, Leptolyngbya, Plectolyngbya, and Phormidesmis, as well as some new and previously undescribed cyanobacteria, were isolated from corresponding soil samples to clarify their taxonomic status. As a result, a unique collection of Antarctic cyanobacteria isolated from soils was obtained for the first time. The strains were described according to the modern polyphasic taxonomy methods based on an integrated assessment of morphological and molecular-genetic features. Phylogenetic analysis of primary 16S rRNA sequences and peculiarities of secondary structures of internal transcribed spacers enabled us to identify new taxa of potentially endemic cyanobacteria among the strains studied. The high level of similarity between the 16S rRNA gene sequences of soil strains and those previously found in benthic mats of water bodies in the Larsemann Hills confirmed the ability of cyanobacteria to expand beyond different ecological niches and to adapt to contrasting environmental conditions.