Valorization of Residual Babassu Mesocarp To Obtain Lipases and Laccases by Solid-State Fermentation

The growing life expectancy of the world's population has demanded more significant inputs of food and energy, stimulating the industrialization of agriculture, with the subsequent generation of residual lignocellulosic biomass of various kinds, where new technologies for its valorization and reinsertion into the production chain are essential. Babassu (Attalea speciosa Mart. Ex Spreng), a palm native to the north and northeast of Brazil, plays a critical role in the economic development of these regions, with notable applications in the oil industry, generating large quantities of residual babassu mesocarp (BM). In this study, BM was investigated as a matrix for the production of lipases and laccases, enzymes of great biotechnological importance, by solid-state fermentation (SSF) with Trichoderma harzianum (IOC4042) and Geotrichum candidum (CCT1205). The in natura (IN-BM) and defatted (DEF-BM) materials were fermented with hydration solutions containing 3-7 salts, combined with glucose or sucrose. The best enzyme activity results were obtained with solutions of 7 salts and glucose, where maximum lipase activity was demonstrated by G. candidum IN-BM (33.14 ± 0.017 U·mL^-1) and the laccase activity by T. harzianum in DEF-BM (0.524 ± 0.016 U·mL^-1). Laccase production was also demonstrated for the first time with G. candidum in DEF-BM (0.441 ± 0.069 U·mL^-1). The results showed for the first time that residual babassu mesocarp is a promising matrix for the bioproduction of lipases and laccases by G. candidum and T. harzianum through a simple and competitive methodology, adding value to an agro-industrial waste.