Application of a Biosurfactant from Candida tropicalis UCP 0996 Produced in Low-Cost Substrates for Hydrophobic Contaminants Removal

Abstract

Contamination by petroleum and its by-products causes serious damage, which has awakened great attention to the development and application of innovative technologies for the removal of these contaminants. In this sense, biosurfactants have been successfully applied in recent years as remediation agents in impacted environments. Biosurfactants are amphipathic molecules with hydrophobic and hydrophilic portions that act between fluids of different polarities (oil/water and water/oil), allowing access to hydrophobic substrates and causing a reduction in surface tension, an increase in the area of contact of hydrocarbons enhancing mobility, bioavailability and biodegradation of such compounds in the environment. This work describes the environmental application of a biosurfactant produced from Candida tropicalis UCP 0996 cultivated in a medium formulated with low-cost substrates. Fermentations were conducted in the medium supplemented with 2.5 % waste frying oil, 2.5 % corn steep liquor and 2.5 % molasses at 28 ºC during 120 h under 200 rpm. The medium surface tension was reduced from 55 mN/m to 30.4 mN/m. A Critical Micelle Concentration (CMC) of 0.6 % was obtained from the isolated biosurfactant. Biosurfactant application demonstrated an ability to disperse 70.95 % of motor oil on seawater surface at 5xCMC. Stone washing tests showed 46.02 and 56.18% removal at 2xCMC and 5xCMC of biosurfactant concentration, respectively, and testing for oil biodegradation showed results around 73.8 % for motor oil biodegradation by indigenous marine bacteria and fungi from the Suape Petrochemical Complex seawater, Pernambuco State, Brazil. The results obtained with the biosurfactant produced by Candida tropicalis UCP 0996 under the conditions tested above show the promising properties of this biomolecule for use in bioremediation of hydrophobic compounds in marine environment.