Potential of the Aspergillus labruscus ITAL 22.223 as a producer of cellulolytic enzymes and xylanase under solid-state fermentation

Background: The enzymatic hydrolysis of the lignocellulosic biomass to obtain saccharides that can be used for the production of bioethanol is an important field in the renewable energy area. For this purpose, fungal cellulases and xylanases can be applied. Methods: Aspergillus labruscus ITAL 22.223 was cultured under SSF with agroindustrial residues and by-products as substrates, humidified with different moistening agents, at different proportions (1:0.5, 1:1, 1:1.5 and 1:2; m/v), for different periods (24-216 h) at 25ºC. The extract obtained was used for determination of the cellulase and xylanase activities. The influence of temperature, pH and different compounds on xylanase activity was analyzed. Results: A. labruscus produced cellulases and xylanase under solid-state fermentation (SSF) using agroindustrial by products and residues as carbon source/substrates. The best production of β-glucosidase (6.3 U/g of substrate) was obtained in the presence of rye bran, whereas for the CMCase it was in the presence of crushed soybean (5.1 U/g of substrate) and xylanase using oat bran (74.8 U/g of substrate) as substrates, for 168 h of cultivation at 25ºC. Considering the high xylanase production, the best moistening agent and its proportion (tap water, 1:2 m/v) were determined. Optimum of temperature and pH for xylanase activity was determined as 55ºC and pH 5.5. The xylanase activity was inhibited by different salts, with exception of MnSO4. It was also inhibited by organic solvents, detergents, EDTA, urea and β-mercaptoethanol. Conclusions: The fungus A. labruscus presented potential to produce enzymes from the cellulolytic complex and xylanase using low cost substrates.