Abstract

The current work aimed to use agro-industrial wastes as a strategy to obtain biosurfactant from a new Candida tropicalis UCP 1613 isolated from mangrove sediments of Rio Formoso, Pernambuco State, Brazil. The yeast was identified based on 18S rRNA sequencing method and blast homology search. The promising strain showed the ability to use an optimal composition of a cheap medium containing whey (3%), cassava wastewater (7%) and soybean post frying oil (10%) during 96h which reduced significantly the surface tension from 70 to 28.8 mN/m. The yield of the biosurfactant obtained was 4.9 g/L and the minimum value of critical micelle concentration was 1.5%. In addition, this was isolated and characterized as an anionic polymeric molecule, composed of proteins (51%), lipids (37%) and carbohydrates (11%), and confirmed by Fourier transform infrared spectroscopy (FTIR) analysis. Also, biosurfactant was capable in forming stable emulsions at different ranges of temperature, pH and salinity. Alternatively, the biosurfactant displayed no toxicity against the different vegetable evaluated seeds Brassica oleracea, Lactuca sativa L. and Solanum lycopersicum. The antimicrobial activity of this biosurfactant was verified showing the main efficacy against Gram-positive bacteria besides inhibiting the antifungal activity against the yeast tested. The results obtained suggest its potential application to pharmaceutical, as well as environmental area.

Key words: Candida tropicalis, mangrove sediment, oil dispersion, biosurfactant.