ABSTRACT The thermophilic fungus Acrophialophora nainiana produces extracellular xylan-degrading enzyme when grown in liquid-state media containing banana stem, wheat bran or sugar cane bagasse as carbon source. The pattern of enzyme induction was influenced by the type of lignocellulosic substrate present in the medium. Fractionation of crude extract samples on ultrafiltration and gel-filtration chromatography showed enzyme multiplicity, which was also evidenced by zymogram analysis of xylanase. Endoglucanase and xylanase were characterized for their optimal temperature and pH, thermostability and stability in optimal pH, Km, adsorption on avicel and synergistic effect. Endoglucanase was more active at temperature of 40-50oC and pH 4.5-5.5 and xylanase, at 55-70oC and pH 5.5-7.0. Both activities were stable when pre-incubated at 50oC and 60oC and their half-life on optimal pH varied from 4 hours to above 15 days. Apparent Km value varied from 0.22 to 14.47 mg.mL-1. Synergistic effect was observed for xylanase activities from sugar cane bagasse, wheat bran and banana stem extracts. In addition, xylanases were able to bind to avicel.
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