Alcanivorax borkumensis SK2

The gammaproteobacterium Alcanivorax borkumensis is a cosmopolitan marine bacterium isolated from a seawater sediment sample in the North Sea that uses oil hydrocarbons as its exclusive source of carbon and energy. Although barely detectable in unpolluted environments, A. borkumensis becomes the dominant microbe in oil-polluted waters. This unusual rod-shaped slow-growing marine hydrocarbonoclastic bacterium is able to grow on a highly restricted spectrum of substrates, predominantly alkanes-2. Using n-alkanes as a sole carbon source causes the strains to produce extracellular and membrane-bound surface-active glucose lipids. These biosurfactants (anionic glucolipids) reduce the surface tension of water, acting as a natural emulsifier, and facilitate emulsification of alkanes, enhances their bioavailability and increases the degradation rate of these hydrophobic organic substrates. Phenotypic analysis showed a restricted nutritional profile, high halotolerance, the absence of fermentative metabolism and a low G+C content. A. borkumensis has a streamlined genome with a paucity of mobile genetic elements and energy generation-related genes, but with a plethora of genes accounting for its wide hydrocarbon substrate range and efficient oil-degradation capabilities. The genome further specifies systems for scavenging of nutrients, particularly organic and inorganic nitrogen and oligo-elements, biofilm formation at the oil-water interface, biosurfactant production and niche-specific stress responses. The unique combination of these features provides A. borkumensis with a competitive edge in oil-polluted environments. This genome sequence provides the basis for the future design of strategies to mitigate the ecological damage caused by oil spills. (EBI Integr8)