Production and formulation of a new low-cost biosurfactant to remediate oil-contaminated seawater

The aim of the present study was to produce biosurfactants using three bacterial strains (Pseudomonas cepacia CCT6659, Bacillus methylotrophicus UCP 1616 and Bacillus cereus UCP 1615) cultivated in mineral medium containing different carbon (glucose, sucrose, molasses and waste frying oil) and nitrogen [NH4NO3, (NH4)2SO4, peptone, yeast extract and corn steep liquor] sources. B. cereus stood out as the best biosurfactant producer when inoculated with a 1.5% cell suspension and cultivated at 28 °C and 200 rpm in 2.0% molasses and 1.0% corn steep liquor for 48 h. Under these conditions, medium surface tension was reduced to 26.2 ± 0.2 mN/m, and biosurfactant concentration achieved 2.05 ± 0.32 g/L. The biosurfactant showed a critical micelle concentration of 0.90 ± 0.05 g/L, proved to be highly stable in wide ranges of pH, salt concentration and heating temperature, and exerted low toxicity to larvae of Artemia salina as a marine environmental bioindicator. Structural characterisation of biosurfactant suggested a lipopeptide composition. The biotensioactive agent was shown to effectively remove motor oil adsorbed to marine rock (91.0 ± 0.4%) and to disperse it in seawater (70.0 ± 0.4%). The biosurfactant formulated with 0.2% potassium sorbate demonstrated considerable potential for application in the petroleum industry, where it could be successfully used as a commercial product to mobilize oil in marine environments.