Optimization of enzymatic saccharification of industrial wastes using a thermostable and halotolerant endoglucanase through Box-Behnken experimental design

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.

GRAPHICAL ABSTRACT

HIGHLIGHTS

• Penicillum roqueforti ATCC 10110 produced an endoglucanase in culture media containing only agro-industrial wastes.

• The exploitation of agro-industrial wastes increases the added economic value of these materials and facilitates the management of solid wastes.

• SEM confirmed the structural changes in the waste biomass induced by saccharification.

• The Box-Behnken design, used for saccharification optimization, increased the production of fermentable sugars by 41.5 times without any pretreatment of the agro-industrial wastes.

Keywords:

• Agro-industrial waste
• enzymes
• lignocellulosic materials
• response surface methodology

Acknowledgments

The authors are grateful to the Brazilian Ministry of Education’s Coordination for the Improvement of Higher Education Personnel (CAPES), the Brazilian National Council for Scientific and Technological Development (CNPq) and the Alagoas State Research Foundation (FAPEAL) for funding this research.

Ethical approval

This article does not contain any studies with human participants or animals performed by any of the authors.

Authors’ contributions

Marta Maria Oliveira dos Santos Gomes collected the data, performed the analysis, and wrote the paper. Izadora Santos Nicodemos collected the data and analysis tools. Monizy da Costa Silva collected the data, analysis tools, and contributed data. Dávida Maria Ribeiro Cardoso dos Santos performed the analysis and contributed data. Floriatan Santos Costa performed the analysis and analysis tools. Marcelo Franco conceived and designed the analysis, and contributed data. Hugo Juarez Vieira Pereira conceived and designed the analysis, and wrote the paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Data openly available in a public repository that issues datasets with DOIs.

Additional information

Funding

This work was supported by a grant from the Brazilian Ministry of Education’s Coordination for the Improvement of Higher Education Personnel (CAPES), the Brazilian National Council for Scientific and Technological Development (CNPq), and the Alagoas State Research Foundation (FAPEAL).