Genomic analysis of Luteimonas abyssi XH031(T): insights into its adaption to the subseafloor environment of South Pacific Gyre and ecological role in biogeochemical cycle.

backgroundLuteimonas abyssi XH031(T), which was previously isolated from subseafloor environment of the South Pacific Gyre (SPG), was an aerobic, gram-negative bacterium, and was identified to be a novel species of the genus Luteimonas in the family of Xanthomonadaceae. The nutrients utilization and metabolic mechanisms of XH031(T) indicate its plasticity. In view of the above characteristics, its genome was sequenced, and an in-depth analysis of the XH031(T) genome was performed to elucidate its adaption to extreme ecological environment.

resultsVarious macromolecules including polysaccharide, protein, lipid and DNA could be degraded at low temperature by XH031(T) under laboratory conditions, and its degradation abilities to starch, gelatin and casein were considerably strong. Genome sequence analysis indicated that XH031(T) possesses extensive enzyme-encoding genes compared with four other Luteimonas strains. In addition, intricate systems (such as two-component regulatory systems, secretion systems, etc.), which are often used by bacteria to modulate the interactions of bacteria with their environments, were predicted in the genome of XH031(T). Genes encoding a choline-glycine betaine transporter and 99 extracellular peptidases featured with halophilicity were predicted in the genome, which might help the bacterium to adapt to the salty marine environment. Moreover, there were many gene clusters in the genome encoding ATP-binding cassette superfamily transporters, major facilitator superfamily transporters and cytochrome P450s that might function in the process of various substrate transportation and metabolisms. Furthermore, drug resistance genes harbored in the genome might signify that XH031(T) has evolved hereditary adaptation to toxic environment. Finally, the annotation of metabolic pathways of the elements (such as carbon, nitrogen, sulfur, phosphor and iron) in the genome elucidated the degradation of organic matter in the deep sediment of the SPG.

conclusionsThe genome analysis showed that XH031(T) had genetic advantages to adapt to subseafloor environment. The material metabolism manifests that the strain may play an important ecological role in the biogeochemical cycle of the SPG, and various cold-adapted extracelluar enzymes produced by the strain may have significant value in application.