Abstract
Contamination caused by hydrocarbons can produce permanent and irreparable damage to the environment. Biosurfactants' production has been intensively studied in the last years, for these agents are biodegradable and have applications in several industrial sectors. Moreover, they have, as well, managed to be ecologically compatible and to carry out the biodegradation of hydrophobic pollutants without damaging the environment. Bioremediation involves using microorganisms or their microbial metabolites for the degradation of contaminants, avoiding the use of chemicals. Biosurfactants are amphipathic biomolecules produced by microorganisms capable of allowing water-oil interaction and also providing biostimulation in the degradation process. In this work, it was used a medium formulated with distilled water supplemented with 2.5% corn steep liquor, 4.0% molasses, and 2.5% frying oil as substrates used to produce a biosurfactant Candida lipolytica (UCP 0988), at 28 ºC during 144 hours under 200 rpm. The biosurfactant's tensoactive properties were determined, and its isolation, toxicity, and bioremediation application were described. The surface tension values indicated a reduction in water tension from 72 to 28 mN/m and a yield of 21g/L in biosurfactant and Critical Micellar Concentration (CMC) of 0.5%. The biosurfactant produced demonstrated stability concerning emulsification and surface tension in extreme pH values (2 to 12), concentrations of NaCl (2 to 10%), and different temperatures (5 to 120°C), and it did not present toxicity to the vegetables. The crude or isolated biosurfactant showed efficiency in removing 57% - 70% of the motor oil in contaminated soil under static conditions. The results obtained demonstrated biosurfactant produced by C. lipolytica showed promising properties for use in bioremediation of hydrophobic compounds.
