The marine bacterium Marinobacter hydrocarbonoclasticusSP17 degrades a wide range of lipids and hydrocarbons through the formation of oleolytic biofilms with distinct gene expression profiles

Abstract Hydrophobic organic compounds (mainly lipids and hydrocarbons) represent a significant part of the organic matter in marine waters, and their degradation has an important impact in the carbon fluxes within oceans. However, because they are nearly insoluble in the water phase, their degradation by microorganisms occurs at the interface with water and thus requires specific adaptations such as biofilm formation. We show that Marinobacter hydrocarbonoclasticusSP17 develops biofilms, referred to as oleolytic biofilms, on a large variety of hydrophobic substrates, including hydrocarbons, fatty alcohols, fatty acids, triglycerides, and wax esters. Microarray analysis revealed 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 with n-hexadecane. The processes related to primary metabolism and genetic information processing were downregulated. Most of the genes that were overexpressed on triolein had unknown functions. Surprisingly, their genome localization was 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. hydrocarbonoclasticusSP17 to occupy a specific niche in marine ecosystems. This paper describes the genetic study of a microbial biofilm dedicated to the degradation of a large panel of marine hydrophobic organic compounds in order to identify the biological processes involved in the recycling of the insoluble oily carbon in oceans. This paper describes the genetic study of a microbial biofilm dedicated to the degradation of a large panel of marine hydrophobic organic compounds in order to identify the biological processes involved in the recycling of the insoluble oily carbon in oceans.