Community structure and psychrophily in Antarctic microbial ecosystems

Molecular based and traditional microbiological techniques were utilized to determine the structure and degree of cold adaptation of a variety of Antarctic bacterial communities. These studies were performed to obtain a better understanding of Antarctic ecosystems and prokaryotic adaptations to low temperature. A high degree of novel diversity was found associated with sea ice communities, marine-derived lake sediments, and quartz stone subliths. 16S rDNA-based clone library analysis of samples from these sites contained many clones exhibiting novelty at the genus and family-level, and o ccasionally at the divisionlevel. Most (non-thermophilic) bacterial phylogenetic divisions were represented. Sediment from hyposaline Clear Lake (Vestfold Hills) contained highly unusual arch aeal clones possibly representing a novel kingdom. Evidence based on cultivation work indicated quartz stone subliths like sea ice are havens for psychrophilic bacteria. The culturability of bacteria from sea ice communities was also demonstrated to be surprisingly high with molecular data matching cultivation data.