The marine bacterium Marinobacter hydrocarbonoclasticus SP17 degrades a wide range of lipids and hydrocarbons through the formation of oleolytic biofilms with distinct gene expression profiles.
Résumé
Hydrophobic organic compounds (mainly lipids and hydrocarbons) represent a significant part of the organic matter in the marine waters and their degradation has thus an important impact in the carbon fluxes within the oceans. However, because they are nearly insoluble in the water phase, their degradation by microorganisms occurs at the interface with water therefore requiring specific adaptations like biofilm formation. We show that Marinobacter hydrocarbonoclasticus SP17 develops biofilms, referred as oleolytic biofilms, on a larger variety of hydrophobic substrates than suspected before, including hydrocarbons, fatty alcohols, fatty acids, triglycerides and wax esters. A microarray analysis confirmed that biofilm growth on n-hexadecane or triolein involved distinct genetic responses together with a core of common genes that might concern general mechanisms of biofilm formation. Biofilm growth on triolein modulated the expression of hundreds of genes in comparison to n36
hexadecane. Processes related to primary metabolism and genetic information processing were down-regulated. Most of the genes over-expressed on triolein had unknown function. Surprisingly, their genome localization is restricted to a few regions identified as putative genomic islands or mobile elements. These results are discussed with regard to the adaptive responses triggered by M. hydrocarbonoclasticus SP17 to occupy a specific niche in marine ecosystems.
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