Optimization of enzymatic saccharification of industrial wastes using a thermostable and halotolerant endoglucanase through Box-Behnken experimental design
Marta Maria Gomes, Izadora Santos Nicodemos, Monizy da Costa Silva, Dávida Maria Ribeiro Cardoso dos Santos, Floriatan Santos Costa, Marcelo Franco, Hugo Juarez Vieira Pereira
Abstract
This study describes the production, characterization and application of an endoglucanase from Penicillium roqueforti using lignocellulosic agro-industrial wastes as the substrate during solid-state fermentation. The endoglucanase was generated after culturing with different agro-industrial wastes for 96 h without any pretreatment. The highest activity was obtained at 50 °C and pH 4.0. Additionally, the enzyme showed stability in the temperature and pH ranges of 40–80 °C and 4.0–5.0, respectively. The addition of Ca2+, Zn2+, Mg2+, and Cu2+ increased enzymatic activity. Halotolerance as a characteristic of the enzyme was confirmed when its activity increased by 35% on addition of 2 M NaCl. The endoglucanase saccharified sugarcane bagasse, coconut shell, wheat bran, cocoa fruit shell, and cocoa seed husk. The Box-Behnken design was employed to optimize fermentable sugar production by evaluating the following parameters: time, substrate, and enzyme concentration. Under ideal conditions, 253.19 mg/g of fermentable sugars were obtained following the saccharification of wheat bran, which is 41.5 times higher than that obtained without optimizing. This study presents a thermostable, halotolerant endoglucanase that is resistant to metal ions and organic solvents with the potential to be applied in producing fermentable sugars for manufacturing biofuels from agro-industrial wastes.