Produção de biossurfactante de baixo custo a partir de resíduos agroindustriais

Abstract

Biosurfactants are actives compounds reducers of the surface tension, metabolites extracted from microorganisms, as well as are stable compounds at different environment conditions. The main characteristics of these compounds are related to biodegradability and to absence of toxicity. In the last few years, a range of studies have been developed in order to include agroindustrial residues in the culture medium for the biosurfactants production. The objective of this study was to evaluate pineapple and cashew residues in a culture medium formulation for the yeast Cryptococcus victoriae, reducing, consequently, the value of the biosurfactant production. In this way, the sugar content of pineapple and cashew extracts was evaluated by the methodology of Miller, 1959. The best carbon and nitrogen sources were selected by factorial design and their ideal concentrations for the culture medium were determined using methodology of response surface and software R. Results showed that the cashew extract had approximately four times more reducing sugars than the pineapple extract, with values of 77.24 g L-1 and 18.87 g L-1, respectively. In addition to the extracts, differents carbon and nitrogen sources were used to evaluate the biosurfactant production. After the selection of the best sources (cashew extract, yeast extract, ammonium citrate and sodium acetate), the experimental planning was performed. This planning provided three significant factors for surface tension reducers in the cashew extract, yeast extract and ammonium citrate culture medium. When the culture medium using these substrates were formulated, surface tension values ranged from 40 to 55 mN m-1. The analysis of the response surface methodology was performed, and evaluation of the individual equations to obtain the general equation and, therefore, the ideals concentrations for reduce the surface tension. Thus, the productive capacity of Cryptococcus victoriae isolated of the Antarctic environment, using agroindustrial residue, was confirmed. In general, better results were observed when the culture medium composed by 19.24 g L-1 of cashew extract, 6.70 g L-1 of yeast extract and 3.30 g L-1 of ammonium citrate was used, reducing the surface tension (54.87 mN m-1) and being a potential medium for industrial and environmental application.