Production of β-glucosidase by Rhodotorula oryzicola and use of enzyme for hydrolysis of sugarcane bagasse delignified

Bioethanol is obtained by hydrolysis of sugarcane bagasse by cellulases. Commercial cellulases are expensive and have a low concentration of ss-glucosidase (EC 3.2.1.21), which decrease hydrolysis efficiency. The present work aims to produce supernatant rich in ss-glucosidase (BGL) using the yeast Rhodotorula oryzicola and apply it in the hydrolysis of delignified sugarcane bagasse. Yeast fermented in a modified YPD (Yeast Peptone Dextrose) medium with 0.5% (w/v) cellobiose and 1.0% (w/v) glucose produced BGL with a specific activity of 1.44 +/- 0.013 U/ mg. Partial purification of BGL by acetone showed a specific activity of 3.48 U/mg. The optimum pH and temperature were 6.02 and 65 degrees C, respectively. BGL partially purified ( BGLppR.oryzicola) by acetone showed tolerance to glucose, with a relative activity of 82.89 +/- 0.11%. The activity increased with the addition of iron sulfate and zinc sulfate and decreased with manganese sulfate. BGL partially purified was thermal stable, with a relative activity of 85.59% after 60 min at 90 degrees C. BGL partially purified applied in the hydrolysis of sugarcane bagasse delignified with 3% (w/w) NaOH + 6% (w/w) Na2SO3 showed a conversion rate of 72.46 +/- 1.60%. The results showed that BGL partially purified is a glucose tolerant cellulase of low-cost, promising the application of bioethanol production.