Psychrotrophic microorganism communities in soils of Haswell Island, Antarctica, and their biosynthetic potential

Diversity of microorganisms plays an important role in the functioning of ecosystems and their response to large-scale environmental changes. Microbial soil communities from virgin Haswell Island, Antarctica, were studied using the serial dilution-spread plate method at two different temperatures. Microorganisms were identified by sporulation, morphological, chemotaxonomic assessment. Nitrogen-fixing cyanobacteria and microalgae prevailed in the samples. Representatives of Chamaesiphon, Dermocarpa, Fischerella, Oscillatoria, Prochlrococcus, Synechococcus, Chlorophyta were detected. Fungal assemblages comprised Aspergillus nidulans, Cladosporium cladosporioides, Alternaria alternata, Mortierella ramanniana, Penicillium verrucosum, Scopulariopsis fusca, Cladophialophora minutissima, Chaetomium gracile, Phoma herbarum, Phialophora fastigiata, Ulocladium consortiale and Candida sp. Actinomycetes were identified by morphological and chemotaxonomic assessment of cell-wall aminoacids and sugars as Streptomyces, Nocardia and Geodermatophilus. Some of the isolated microorganisms formed extracellular enzymes, others biosynthesized substances with antifungal and antibacterial activities. Single psychrotrophic strains have an ability to grow on n-paraffins and naphthalene, and thin-layer chromatographic analyses showed that they synthesized glycolipids. Assays for sugar moiety revealed that they contained different pentoses such as arabinose, xylose or deoxyhexose as rhamnose.