The genome analysis of Oleiphilus messinensis ME102 (DSM 13489T) reveals backgrounds of its obligate alkane-devouring marine lifestyle.

Abstract Marine bacterium Oleiphilus messinensis ME102 (DSM 13489 T ) isolated from the sediments of the harbor of Messina (Italy) is a member of the order Oceanospirillales , class Gammaproteobacteria , representing the physiological group of marine obligate hydrocarbonoclastic bacteria (OHCB) alongside the members of the genera Alcanivorax , Oleispira , Thalassolituus , Cycloclasticus and Neptunomonas . These organisms play a crucial role in the natural environmental cleanup in marine systems. Despite having the largest genome (6.379.281 bp) among OHCB, O. messinensis exhibits a very narrow substrate profile. The alkane metabolism is pre-determined by three loci encoding for two P450 family monooxygenases, one of which formed a cassette with ferredoxin and alcohol dehydrogenase encoding genes and alkane monoxygenase (AlkB) gene clustered with two genes for rubredoxins and NAD + -dependent rubredoxin reductase. Its genome contains the largest numbers of genomic islands (15) and mobile genetic elements (140), as compared with more streamlined genomes of its OHCB counterparts. Among hydrocarbon-degrading Oceanospirillales , O. messinensis encodes the largest array of proteins involved in the signal transduction for sensing and responding to the environmental stimuli (345 vs 170 in Oleispira antarctica , the bacterium with the second highest number). This must be an important trait to adapt to the conditions in marine sediments with a high physico-chemical patchiness and heterogeneity as compared to those in the water column.