Enhanced Biosurfactant Production Using Developed Fed-Batch Fermentation for Effective Heavy Crude Oil Recovery

This study presents a novel and dynamic strategy to enhance rhamnolipid and sophorolipid production using isolated Pseudomonas aeruginosa and Starmerella bombicola, respectively, from an Egyptian oil field. The optimum productivity of rhamnolipid and sophorolipid was observed when 1% of crude oil was used as a carbon source at pH 6 and 3 and temperatures of 30 and 40 °C, respectively. The developed fed-batch cultivation strategy enhanced rhamnolipid and sophorolipid production by 1.4- and 1.96-fold, respectively. A robust complex consisting of the produced biosurfactants separately binding with t-octylphenoxypolyethoxyethanol was examined for enhancing oil recovery. The interfacial tension was reduced from ∼11.83 to ∼0.13 mN/m, and the wettability was modified from the common water-wet state [θ = ∼75–80°] to an excellent water-wet state [θ = ∼14.03–21.71°]. The core-flooding tests showed that the oil recovery process was enhanced for rhamnolipid and sophorolipid complexes by 66.07 and 55.63%, respectively.