Genome Sequencing of Mesonia algae K4-1 Reveals Its Adaptation to the Arctic Ocean

Abstract

The special ecological environment of the Arctic has brought about a large number of salt-tolerant and psychrotolerant microorganisms. We isolated two culturable bacterial strains of the genus <i>Mesonia</i>; one from the Arctic ocean, <i>Mesonia algae</i> K4-1, and one from the tropical sea, <i>Mesonia</i> sp. HuA40. Our genome analysis and phenotypic experiments indicated that <i>Mesonia algae</i> K4-1 is a moderately halophilic and psychrophilic bacterium. <i>Mesonia algae</i> K4-1 can tolerate 3-14% NaCl and grow at a wide range of temperatures from 4 to 50°C. <i>Mesonia</i> sp. HuA40 is a mesophilic bacterium that can only grow with 3-9% NaCl. In addition, the salt adaptation strategy of <i>Mesonia algae</i> K4-1 accumulates organic osmolytes in the cell. RNA helicases, glutathione and organic compatible solutes may play important roles in maintaining the metabolism and physiological function of <i>Mesonia algae</i> K4-1 under cold stress. Moreover, the ability of <i>Mesonia algae</i> K4-1 to adapt to an oligotrophic marine environment is likely due to the synthesis of a large number of extracellular polysaccharides and the secretion of various families of extracellular proteases. This study systematically analyzed the relationship between genomic differentiation and environmental factors of the <i>Mesonia</i> genus and revealed the possible adaptation mechanism of <i>Mesonia algae</i> K4-1 in the extreme Arctic marine environment at the genomic level.