Abstract
Biosurfactants are natural surfactants produced by bacteria, yeasts or fungi from different substrates, including sugars, oils, and alkanes. Biosurfactants are expected to reach more than USD 2 billion by 2020, with industrial applications in microbial enhanced oil recovery (MEOR), removal of contamination by heavy metals, bioremediation, food, cosmetics, pharmaceuticals and biomedicine. The considerable interest in these biobased products is related to their properties, as biodegradability, production from renewable substrates, low toxicity and biocompatibility, diversity for chemical structure and properties, effectiveness even at extreme conditions of temperature, pH and salinity. Despite the advantages, fermentation must be cost-competitive with chemical synthesis, and many of the potential applications that have been considered for biosurfactants depend on whether they can be produced economically. Fermentation medium can represent approximately 30 % of the cost for a microbial fermentation. In this work we used a medium formulated with distilled water supplemented with 5 % (v/v) corn steep liquor, 5 % (v/v) molasses and 5 % (v/v) soybean waste frying oil as substrates to produce a biosurfactant from Candida bombicola, at 28 °C during 120 h under 200 rpm was first produced in 3.0 L bioreactor. The properties of the biosurfactant, toxicity and environmental application were determined. The isolated biosurfactant showed a yield of 61 g/L. The biosurfactant with a critical micelle concentration of 0.5 % and demonstrated low toxicity to the vegetables. The biosurfactant demonstrated stability with regard to emulsification and surface tension reduction in a range of temperatures (4 to 120 °C) and pH values (2 to 12) as well as tolerance to high concentrations of NaCl (2 to 10 %). The cell-free broth was also effective in oil displacement (90 %) in water. The results obtained with the biosurfactant produced show the promising properties of this biomolecule for use in bioremediation of hydrophobic compounds.
