Viruses that infect bacteria (bacteriophages or phages) are the most abundant biological entities in the biosphere. Phages play a central role in shaping microbial communities and regulating global biogeochemical cycles. Two major biological cycles characterize phages: the lytic and the lysogenic cycles. This study focuses on the lysogenic cycle, in which phages integrate into the bacterial genome. The study of bacterium–phage systems in Antarctic environments is of particular interest due to the extreme environmental conditions under which these interactions occur. Antarctic bacteria isolated from different habitats were investigated to characterize their lysogenic viruses. Bizionia argentinensis, Rhodococcus spp. strain ADH, and Agreiaspp. were characterized both in silico and in vitro for the presence of integrated phages (prophages). These prophages harbor a genetic repertoire that may play a central role in host–environment interactions. In addition, some prophage-derived genes (including endolysins, enzymes that lyse bacterial cell walls) have potential biotechnological applications. In particular, enzymes adapted to function at low temperatures could be exploited for industrial use.
