Improvement of endoglucanase production by Aspergillus brasiliensis in solid-state fermentation using cupuaçu (Theobroma grandiflorum) residue as substrate.

Abstract

Optimize the production of Aspergillus brasiliensis endoglucanase in a solid-phase bioprocess using cupuaçu shell as substrate. The shells were supplemented with nitrogen and phosphorous and used as a substrate. The centesimal and inorganic composition of the residue was determined, and found to be rich in fibres, and possessed essential elements for fungal growth. In the initial cultivation of A. brasiliensis, endoglucanase activity of 7.35Ug-1 was obtained. A factorial experimental design was used to determine the most significant variables for the bioprocess. The interactions between moisture, temperature and nitrogen source were noteworthy (p<0.05). From the rotational central composite design, the optimization of temperature and nitrogen supplementation was obtained, and this reached 40.50Ug-1 , which is an increase of more than five times the value obtained initially. The enzymatic extract was applied as the biocatalyst in the hydrolysis of cupuaçu shells and, after 48h, it was possible to observe the production of reducing sugars. Cupuaçu shell can be used as a substrate for endoglucanase production by A. brasiliensis. The process was optimized for the cultivation temperature and the nitrogen source. The enzymatic extract can be applied in the hydrolysis of lignocellulosic biomass. Cupuaçu shells can be used to produce cellulases, a product of high added value that can generate economic and environmental benefits for communities and companies producing derivatives of the cupuaçu fruit.