Production of thermostable xylanase by thermophilic fungal strains isolated from maize silage

The search for microorganisms able to produce thermostable xylanases with high yield and characteristics desired for industrial applications has been strongly encouraged since such enzymes are widely used in large-scale processes. In the present study, thermophilic fungal strains able to grow at high temperatures (≥55 °C) were isolated from maize silage. The strains were molecularly identified and used for the production of extracellular xylanase by solid-state fermentation using corn cobs as support-substrate material. Species from the genera Rhizomucor and Aspergillus were identified among the isolated strains and these species demonstrated good ability to produce xylanase under solid-state fermentation conditions. Maximal values of enzymatic activity (824 U/g) and productivity (8.59 U/g.h) were obtained with Rh. pusillus SOC-4A (values per g dry weight of fermented medium). The xylanase produced by this fungus presented thermal stability at 75 °C, with maximum activity at 70 °C and pH 6.0, revealing, therefore, great potential for application in different areas.