Glycolipids of Pseudomonas and Rhodococcus oil-degrading bacteria used in bioremediation preparations: Formation and structure

• Five effective oil-degrading microbial strains were glycolipids producers.
• Pseudomonas fluorescens and Pseudomonas putida produced rhamnolipid B and its homologues.
• Trehalose tetraesters were extracellurar surfactants produced by Rhodococcus sp.

We studied formation and structural features of biosurfactants produced by five oil-degrading Pseudomonas and Rhodococcus strains. These bacteria were found to be capable of intense formation of extracellular glycolipid biosurfactants when grown on mineral salts medium with 2% hexadecane. Under these conditions, the surface tension of the cultures decreased from 77 mN/m to 31–34 mN/m. The strain Rhodococcus sp. S26 forming up to 780 mg glycolipids/l of culture medium proved the most efficient biosurfactant producer. Extracellular glycolipids were purified from the crude extracts by column chromatography. Their structural features were determined by thin layer chromatography and electrospray ionization mass spectrometry. Strains Pseudomonas putida BS3701 and Pseudomonas fluorescens 142NF synthesized a number of glycolipids identified as rhamnolipid B and its homologues. Glycolipids produced by Rhodococcus sp. X5 and Rhodococcus sp. S26 were assigned to trehalose tetraesters.