The marine environment: a promising source of microorganisms for the production of biosurfactants

Marine organisms have developed strategies to cope with specialised environmental conditions. One common strategy is the production of biosurfactant molecules to access specific nutrients and to promote biofilm development. In this study, two different marine species from the genera Marinobacter and Halomonas were cultured to investigate biosurfactant production. The strains were able to reduce the surface tension (ST) of the fermentation broth from 58 mN/m to 30 mN/m using rapeseed oil as a carbon source. The biosurfactant produced by Marinobacter species MCTG107b was isolated, purified and structurally characterized as rhamnolipid with 14 different congeners. The Halomonas TGOS-10a was able to produce simultaneously two bioproducts a biosurfactant and a bioplastic polyhydroxyalkanoate (PHA). The biosurfactant produced by the two strains showed antimicrobial activity against the pathogenic microorganisms Pseudomonas aeruginosa and Staphylococcus aureus. Finally, the Galleria mellonella waxworm infection model showed that the strains were non-pathogenic. The results show the prospects of marine-derived biosurfactants as promising bio-ingredients for consumer product development due to their surface-activity, non-toxicity and anti-microbial properties.