Optimization of hydrolases production from cassava peels by Trametes polyzona BKW001

Abstract

The saccharification of biomass with hydrolases from fungi is considered as an efficient and sustainable approach to obtain fermentable sugars. The expression of these hydrolytic enzymes by fungi is mainly by a substrate-induced mechanism, which depends on prevailing environmental conditions. Trametes polyzona, a white rot fungus, is regarded as one of the most efficient producers of hydrolases for the hydrolysis of biomass. This study sought to examine and optimize cultivation conditions for the efficient production of hydrolases by Trametes polyzona (T. polyzona). Hydrolase production by T. polyzona was examined using parametric optimization. Crude enzyme extracts obtained under varying cultivation conditions were profiled for endoglucanase, betaglucosidase, exoglucanase, xylanase and amylase activities to determine the optimal conditions for hydrolase production. Significantly (p ≤ 0.05) higher endoglucanase (1.97 ± 0.04 U/mL), xylanase (0.87 ± 0.05 U/mL) and amylase (1.16 ± 0.27 U/mL) activities were achieved by the solid-state cultivation in comparison to the submerged cultivation of T. polyzona. Maximum production of endoglucanase, betaglucosidase, exoglucanase, xylanase and amylase were recorded at 14 days of cultivation on cassava peels, 60% moisture level, temperature 30°C, pH 6, and supplementation with 0.3% w/w urea and 0.03% w/w Mg2+. A solid to liquid ratio of 1:2 was found to be ideal for the solid-liquid extraction of hydrolases. This study has proven that optimization of cultivation conditions is an efficient approach to enhance hydrolases production by T. polyzona BKW001. The hydrolase profile of the enzyme cocktail suggests a potential suitability and adoption for ethanol biorefinery from lignocellulosic biomass.