Abstract
Surfactants are chemical compounds that have the property of being preferably located between phases with different degrees of polarity, which may be of synthetic or natural origin, the latter being called biosurfactants. These have several advantages over chemical surfactants, since they can be produced from agroindustrial substrates and have low toxicity, high biodegradability and compatibility with the environment. Thus, this work had studied the production of a biosurfactant by the yeast Saccharomyces cerevisiae URM 6670 using agroindustrial residues. The yeast was grown in six different media, substituting the original sources of carbon and nitrogen from the mineral medium by agricultural wastes (soybean frying oil and corn steep liquor) at 150 rpm for 120 h and temperature 28 °C. After choosing the best production condition by surface and interfacial tension and emulsification index (E24) measurements, the physicochemical composition, CMC and particle size distribution of the biomolecule was determined. The surface and interfacial tensions obtained ranged from respectively 26.45 ± 0.02 to 45.88 ± 0.15 mN/m and 6.87 ± 0.04 to 14.31 ± 0.14 mN/m, with the best results obtained for the biosurfactant produced only in the presence of the residues. For the emulsification index, the results were also more promising from the optimized media, ranging from 3.77 ± 0.10 % to 94.58 ± 2.43 %. Regarding the physicochemical composition, the value obtained for the isolated biosurfactant indicated its glycolipidic nature (19.64 ± 3.66 % of carbohydrates and 80.04 ± 3.86% of lipids). In determining CMC, a value of 0.8 g/L was obtained; and particle size distribution with best result using emulsion solution at 2xCMC concentration. Therefore, the use of agroindustrial residues for the production of biosurfactant by Saccharomyces cerevisiae URM 6670 is promising, allowing the reduction of costs associated with the raw material.
