Monday, May 4, 2009
5-83
Nitrogen source optimization for cellulase production by Penicillium funiculosum, using experimental planning
Cellulases are enzymes able to hydrolyze β-1,4 glycosidic bonds of celullose and have many applications in food and textiles industries and in biofuels production. For this purpose these enzymes can be produced by using agricultural and agroindustrial wastes as nutrients sources, carbon particularly. Sugar cane bagasse is one of the most abundant wastes in Brazil which cellulose composition is between 34 and 37% on dry weight. However, this waste is poor in nitrogen, one of the most important nutrients for the microorganism that is used for the synthesis of structural and catalytic proteins. Thus, this work aimed at evaluating and optimizing different nitrogen sources for cellulases production by submerged fermentation of sugar cane bagasse. The nitrogen sources, urea, ammonium sulfate, peptone and yeast extract ,were analyzed in two levels with three repetition of the central point. The results were evaluated by analysis of effects (T test), ANOVA and optimized using response surface methodology. The filamentous fungus Penicillium funiculosum was used in enzymes production, and fermentation was carried out in Erlenmeyer flasks containing sugar cane bagasse added of the corresponding nitrogen source. The fermentation process was carried out for 72 hours at 30 °C and stirred at 200 rpm. The crude extract was obtained by centrifugation and then the filter paper activity, endoglucanase and β-glucosidase were determinated. Urea and yeast extract presented significance to cellulase production among the evaluated sources. Desirability function indicated that the optimum condition of urea and yeast extract was 0.424 and 0.884 (coded values), respectively.
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