Holovan V. Diversity of viruses of microorganisms in Argentina islands, Antarctica.

The thesis is devoted to the study of the biodiversity, biological and genetic properties of bacteriophages, common in soil biotopes of the Argentine islands in Antarctica. Bacteriophages are intracellular parasites; their life cycle is completely dependent on the host bacterium, namely on metabolic activity, environmental conditions and defense systems against viral infections. To assess and understand the functioning of the phage-bacterial system, it is important to apply a systematic (integrated) approach and a holistic understanding of the biology of bacterial viruses. There have been almost no studies related to the study of bacteriophages in Antarctica, which is due to the lack of methods, model systems and the remoteness and climatic conditions of the Antarctic region. The work required the optimization of traditional methods for phage isolation and purification, which resulted in the successful production of 32 phage isolates, which were subsequently examined by electron microscopy. According to morphological characteristics, phages belonged to three taxonomic families: phages with long contractile tails of the family Myoviridae, phages with long incompressible tails of the family Siphoviridae and phages with short tails of the family Podoviridae, order Caudovirales. Studies of viral diversity at the location of the Ukrainian Antarctic Research Station "Academician Vernadsky", Galindez Island. Galindez, Antarctica, founded by the Department of Virology of the Taras Shevchenko National University. But there have been no studies dedicated to bacteriophages in soils. The main reason for the lack of information devoted to soil viruses in Antarctica is the difficulty of culturing both viruses and their bacterial hosts. In order to identify and determine the biological properties of phages, the presence of host bacteria, through which the phage can reproduce, is a prerequisite. As viral biodiversity in any ecosystem depends on the composition of bacterial populations, we isolated and identified eight bacterial cultures. Bacterial cultures were subsequently used to accumulate viruses as well as to establish phage-bacterial interactions. This work creates the first comprehensive insight into the distribution of bacteriophages in Antarctic soil biotopes. This thesis contains unique studies of virus biodiversity in Antarctica, with a particular focus on soil phages. Characterisation of phage diversity, studies of biological properties of the functioning of the phage-bacterial system and genetic and molecular characterisation of some phages contribute to our understanding of the Antarctic region.