Extracellular neutral lipids produced by the marine bacteria Marinobacter sp

We analyzed the production of neutral lipids by the marine hydrocarbonoclastic bacteria Marinobacter sp. strain PAD-2 using hexadecane or succinate as the sole carbon source. Results showed that strain PAD-2 was able to grow and reduce the surface tension to 33±1.5 mN m(-1) and 58±1.5 mN m(-1) when n-hexadecane or succinate was used as the sole carbon source, respectively. The lipophilic compounds produced by Marinobacter sp. strain PAD-2 were extracted, and then crude lipophilic compounds, expected to be wax ester-like lipids, were analyzed by thin layer chromatography (TLC) . Furthermore, the lipophilic compound demonstrating surface activity was purified and subjected to gas chromatography/mass spectrometry (GC/MS) analysis. Although these did not give definite structural information due to the weak molecular ion peak (M(+)) , one component Ma-1 showed almost the same mass spectrum as that of component Fa-2, which represented a biosurfactant derived from Dietzia maris reported previously. Cell hydrophobicity was measured by a test of bacterial adhesion to hydrocarbons. A higher hydrophobic cell surface was observed in strain PAD-2. Extracellular wax ester-like compounds seem to be one type of the surface active compounds when bacteria grow on hexadecane or succinate as the sole carbon source.