Seleção de leveduras produtoras de biossurfactantes isoladas de sedimentos de manguezais da APA Costa dos Corais, Alagoas, Brasil

Abstract

Coastal ecosystems of high diversity such as mangroves are promising to the bioprospecting of molecules of biotechnological interest, such as biosurfactants. Biosurfactants are surfactant molecules, with low toxicity, capable of reducing surface tension, and can tolerate different temperatures, salinity, or pH, with various applications. The objective of this study was to select yeasts from mangrove sediments of the coast of Alagoas (Santo Antônio and Tatuamunha rivers) for the potential to produce biosurfactants. The yeasts were initially submitted to literature search for the identification of species not yet described for biosurfactant production. Then, 40 isolates of unreported species were evaluated for emulsion index IE24%. After initial selection, 6 Candida (Pichia) pseudolambica strains with IE24% ≥ 50% were selected for evaluation of surfactant properties. Afterwards, the effects of different temperatures, salinities, and pH on the biosurfactants as well as the emulsification capacity (IE24%) in different hydrocarbons were evaluated. The production of lipases was also evaluated, and subsequently, the functional groups of biomass samples were characterized via Fourier transform mid-infrared vibrational spectroscopy (FTIR). The C. (Pichia) pseudolambica strains showed ability to reduce water surface tension between 36.69 mN/m to 42.47 mN/m, tolerance to pH conditions (2-4), emulsions ranging between 51% and 63%, and resistance to high temperatures (90 to 150 ºC). The cell cultures showed ability to emulsify different hydrocarbons and lipase activity. Spectroscopic analysis (FTIR) of the biomass samples revealed the existence of several functional groups typical of a complex structure of carbohydrate and lipid nature. Therefore, strains of C. (Pichia) pseudolambica from mangroves of the Northeast region of Brazil showed potential for biosurfactant and lipase production, revealing the possibility of biotechnological use to be better explored.