Rhamnolipid and surfactin production from olive oil mill waste as sole carbon source

Olive mill waste (OMW) creates a major environmental problem due to the difficulty of further waste processing. In this work we present an approach to give OMW added value by using it for the production of biosurfactants. Two bacterial species, Pseudomonas aeruginosa and Bacillus subtilis, were grown with OMW as the sole carbon source. Glycerol and waste frying oil were used as comparative carbon sources. B. subtilis produced surfactin (a lipopeptide) at a maximum concentration of 3.12 mg/L with 2% w/v of OMW in the medium, dropping to 0.57 mg/L with 10% w/v of OMW. In contrast, P. aeruginosa produced 8.78 mg/L of rhamnolipid with 2% w/v OMW increasing to 191.46 mg/L with 10% w/v OMW. The use of solvent-extracted OMW reduced the biosurfactant production by 70.8% and 88.3% for B. subtilis and P. aeruginosa respectively. These results confirm that OMW is a potential substrate for biosurfactant production.