Abstract
Contaminations caused by hydrophobic compounds represent a permanent hazard to the environment and global development. Methods of cleaning and remediation are essential to avoid intoxication and death of living organisms after disasters with these compounds. The application of biosurfactants is one of the methods used to remove to remove oils. These amphipathic molecules reduce surface and interfacial tensions of two immiscible phases to improve mixing. Such compounds are produced spontaneously by various organisms, such as bacteria with the advantage of lower toxic activity, more biodegradability and stability under adverse environmental conditions when compared to chemical surfactants. Thus, this study investigated the potential application of a biosurfactant for enhanced removal capability of motor oil from contaminated water, under laboratory conditions. The biosurfactant was produced by Bacillus cereus UCP 1615 isolated from seawater, grown in mineral medium supplemented with 2% soybean waste frying oil and 0.12% peptone, in a bioreactor of 3 L, on a stirring of 250 rpm, for 48 h, at 28°C. After producing, were evaluated the surface tension, production and critical micelle concentration (CMC) of the biosurfactant, the obtained results were 27.5 mN/m, 4.6 g/L and 500 mg/L, respectively. Tests were conducted to examine the effectiveness of the biosurfactant. Firstly, it was evaluated the oil dispersion capacity in the crude biosurfactant using at the CMC concentration was enough to achieve favorable results (above 85%) in ratio 1:1 (biosurfactant/motor oil). Similar result was obtained with isolated biosurfactant in ratio 1:10. Thereafter, was measured the biodegradation using the biosurfactant and its microbial producing specie in the removal of oil contaminated seawater. The results showed that the presence of the biosurfactant in association with microorganism increased the degradation of the motor oil up to 96% in 27 days of incubation in seawater in relation to the control. Thus, the biosurfactant produced by Bacillus cereus UCP 1615, a promising strain that possibly had the metabolism stimulated to enhance the production of biosurfactant, has application potential for remediation processes in marine environments contaminated with hydrophobic compounds.
