RESUMO
Demand for fungal xylanases in industrial biotechnological processes shows a clear increase worldwide, so there is an interest in adjusting the conditions of microbial xylanases production. In this study, the ability of the fungus Fusarium solani to produce extracellular xylanases with low cellulolytic activity was optimized by Box Wilson design. The best culture conditions were determined to obtain a crude enzyme preparation with significant xylanolytic activity and little cellulolytic activity. In most treatments, the xylanolytic activity was higher than the cellulolytic activity. A negative effect on the production of endoxylanases, ß-xylosidases and endocellulases was observed with the increasing of xylan concentration. Increasing the incubation time adversely affected the production of endocellulases and ß-xylosidases. According to the mathematical model and experimental tests, it is possible to produce endoxylanases with minimal endocellulase activity increasing incubation time and the concentration of ammonium sulfate. The optimal culture conditions to produce a greater amount of endoxylanases (10.65U/mg) and low endocellulases from F. solani were: 2.5% (w/v) xylan, 5.0, 2.0 and 0.4g/l, of yeast extract, ammonium sulfate and urea, respectively, with 120h of incubation.
