Genomic analysis of Marinomonas profundi M1K-6 reveals its adaptation to deep-sea environment of the Mariana Trench.

The Mariana Trench is the deepest site on earth with diverse extreme conditions such as high hydrostatic pressure, low temperature and lack of light. Organisms surviving in this extreme environment and their life strategies have been largely uninvestigated. Here, we report the complete genome of Marinomonas profundi M1K-6, isolated from the Mariana Trench deep seawater. The assembled genome comprised 3,648,059 bp without any plasmid. Gene annotation showed that strain M1K-6 possesses a series of genes encoding cold-shock proteins, DEAD box RNA helicase and enzymes for biosynthesis of unsaturated fatty acids, implying its high cold tolerance. Abundant genes responsible for transports of ion, branched-chain amino acids and organic compatible solutes were detected, which could maintain cellular osmotic balance disturbed by high hydrostatic pressure. In addition, detected genes (related to storage carbon, transport systems and two-component regulatory systems) could help strain M1K-6 to improve its ecological fitness in the deep-sea microaerobic and nutrient-limiting environments. Genomic information on M. profundi M1K-6, provides insights into the adaptation strategies of Marinomonas spp. in the extreme deep-sea environment of the Mariana Trench.