| Summary: | Antarctic meltwater ponds are unique unexplored biotopes characterized by a high complexity of microbiota and affected by ever-changing ecological factors. Cold-adapted bacteria isolated from Antarctic meltwater ponds represent excellent model organisms to study climate change induced stress adaptation. Moreover, these bacteria may possess biotechnologically relevant properties and can be used for production of valuable chemicals. The main aim of this PhD work was to perform comprehensive phenotypic characterization of newly isolated cold-adapted bacteria from unexplored sea-affected meltwater ponds in the Thala Hills Oasis (Enderby Land, East Antarctica). As a first step of the PhD work, physicochemical and biological analysis of water from the studied meltwater ponds as well as isolation and identification of bacteria, their physiological characterization and evaluation of their antibiotic susceptibility was performed in Paper I. It has been shown that the meltwater ponds have water with alkaline pH and can be characterized by a relatively high bacterial activity. In total of twenty-nine bacterial isolates were retrieved from the meltwater samples. By using 16S rRNA gene sequencing, the isolated bacteria were classified as Proteobacteria, Actinobacteria, Firmicutes, and Bacteroidetes, belonging to 12 genera where Pseudomonas was the predominant genus. Many isolates were psychrotrophic, capable of producing pigments and extracellular enzymes, where lipases and proteases were prevalent. Antibiotic susceptibility testing revealed a presence of resistance to at least one antibiotic for most of the isolates and seven isolates showed multi-resistance. Alterations in cellular lipids are considered as one of the adaptation strategies to harsh environmental conditions. Temperature is one of the most important factors inducing tremendous biochemical changes in bacterial cells. Temperature-induced changes of cellular lipids and other biomolecules in the isolated Antarctic meltwater bacteria were studied in Paper II. A ...
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