Resumo

Facing the great and increasing use of surfactants in the industries, new alternatives are emerging aiming to mitigate the impact of these substances in the environment, since they are especially derived from petroleum. Against this background, surface active compounds (SACs) rise as a good option, once they are produced by microorganisms but are also amphiphile molecules able to act on surfaces, reducing surface and interfacial tensions of liquids and contributing to stabilize emulsions through the micelles formation. Because of their biological origin, these agents present some advantages, as low toxicity and higher biodegradability and stability to physicochemical changes, which stimulate their use in bioremediation processes, among other industrial applications. Furthermore, SACs can be produced from biological wastes, so providing a proper disposal to the residues and decreasing the yield costs. Therefore, an extracellular lipopolysaccharide isolated from the yeast Trichosporon mycotoxinivorans CLA2 and whose production was previously optimized using a biodiesel synthesis waste was analyzed for its surfactant properties, its ability to form emulsions under different conditions and its flocculating activity. The biomolecule was able to reduce the surface tension only at high concentrations, enlarging the drop diameter in 43,33% at 100 mg/mL. But the emulsification properties were remarkable, reaching the highest emulsification index of 81,82% at the concentration of 8,6 mg/mL and showing to be a good bioemulsifier. This significant emulsifying activity remained stable in the pH range from 4 to 7, for the treatment at temperature of 100 ºC for up to one hour and for the addition of up to 30% of NaCl e KCl. For different substrates, the bioemulsifier exhibited good activity for hydrocarbons such as hexadecane, kerosene, toluene and xylene, but was unable to emulsify some vegetable oils. Because of being a polymeric agent, its flocculation activity was tested and showed ability to double the kaolin sedimentation speed and to lay down activated carbon at a rate of 0.034 cm/s, which corresponds to half of that obtained with the commercial flocculant polyacrylamide. These properties of the SAC produced by T. mycotoxinivorans CLA2 demonstrate industrial application potential especially if considered its previous production optimization from biodiesel waste.