ABSTRACT

Viruses have played critical roles in the adaptation of life to a variety of new environments and have been recognized as key players in the regulation of the carbon and nitrogen cycles in the oceans. However, our understanding of viruses in extreme environments is largely at the stage of discovery, and only a few studies have clearly demonstrated the importance of viruses in adaptation. The most well-studied examples are from plants, but microbial viruses from extreme environments are revealing an entirely new world of virology, with structures and genomes unlike anything seen elsewhere. A few studies are now indicating that viruses may be involved in providing key metabolic genes for their hosts that have adapted to the use of non-conventional sources of energy. Viruses are also involved in horizontal gene transfer and in regulating host populations.