BIOPROSPECÇÃO DE LEVEDURAS COM POTENCIAL BIOTECNOLÓGICO PARA A PRODUÇÃO DE COMPOSTOS ATIVOS DE SUPERFÍCIE

Abstract

Surface active compounds (CAS) of microbial origin, with biosurfactant and bioemulsifying properties, have become an active group of biomolecules with potential use in a variety of industrial and biotechnological applications. In this sense, the present study aimed to isolate from fermented fruits with potential for the production of CAS of biological origin. The tests were carried out using yeasts in submerged cultivation in a rotating incubator. The influence of temperature, pH and salt concentration factors was proven. The best result was sought by monitoring production through substrate consumption, reduction of surface tension (ring method) and emulsification activity (E24). The CAS was selected and characterized by gas chromatography. The growth and production kinetics of CAS were proven, in addition, the antimicrobial, antibiofilm and cytotoxicity activity of CAS was evaluated. The results obtained found that the CAS products were identified as Candida krusei (n=6) and Candida metapsilosis (n=7). Candida krusei M4CK isolated from the Byrsonima crassifolia fruit, popularly known as murici, was more efficient in the production of CAS. The compound showed a reduction in surface tension from 72 mN/m-1 to 44 mN/m-1 and was characterized as a bioemulsifier (BE4CK). An E24 equal to or greater than 50% was found in all carbon sources such as olive, sunflower and post-frying oils, and hydrocarbons such as kerosene, hexane and hexadecane. BE4CK had 9-octadecenoic acid as the main fatty acid and the monosaccharides were mannose and glucose. E24 was related to the growth phase. The stability of the emulsions was maintained over a wide range of temperatures, pH and salinity. BE4CK (25 mg/mL) did not show antimicrobial activity against Escherichia coli ATCC 25922, Enterococcus faecalis ATCC 35218, Pseudomonas aeruginosa ATCC 27853 and Staphylococcus aureus ATCC 25923. The compound BE4CK showed, at all concentrations (25 mg/mL to 1.56 mg/mL), significant inhibitory activity on biofilm formation by S. aureus ATCC 25923, E. coli ATCC 25922 and P. aeruginosa ATCC 27853. In addition Furthermore, treatment with BE4CK demonstrated significant eradication for pre-formed biofilms by S. aureus ATCC 25923. The BE4CK compound showed no toxicity in VERO cells and Tenebrio molitor larvae. The OMBECK emulsion, resulting from the combination of BE4CK bioemulsifier and Melaleuca essential oil, inhibited the growth of E. coli ATCC 25922, E. faecalis ATCC 35218 and S. aureus ATCC 25923. This combination was also able to reduce and eradicate the formation of biofilm on polystyrene and polyurethane surfaces of medical devices. Given the results, it appears that the BE4CK bioemulsifier can represent a new source of antimicrobial and antibiofilm agents for biotechnological development.