The biological method besides being more specific and efficient than thermal treatment can result in products of economical interest (e.g. enzymes, mushrooms, animal feed). Pleurotus ostreatus has been used in the bioremediation of pollutants and the degradation of lignocellulosic residue by the action of different enzymes ( Dundar, Acay, & Yildiz, 2009; Haritash & Kaushik, 2009), including the lignocellulolytic enzymes, tannase and phytase ( Batra & Saxena, 2005; Cavallazzi, Brito, Oliveira, Villas-Bôas, & Kasuya, 2004; Collopy & Royse, 2004).
In addition, this fungus produces mushrooms using different lignocellulosic residues ( Dundar et al., 2009; Fan, Soccol, Pandey, Vandenberghe, learn more & Soccol, 2006; Nunes et al., 2012). The P. ostreatus mushrooms have high nutritional value and are sources of protein, carbohydrates, vitamins (e.g. B1, B2 and B3), calcium and iron ( Dundar et al., 2009; Wang, Sakoda, & Suzuki, 2001). Major agroindustrial residues have in its chemical composition higher fibers content with low availably than protein, minerals and vitamins (Villas-Bôas, Esposito, &
Mitchell, 2002). Colonization and solid fermentation AZD6738 by fungi have been used to increase the availably and the nutritional value of these residues (Pereira, 2011; Sánchez, 2009; Villas-Bôas et al., 2002). This procedure has been used with success in cocoa (Alemawor, Dzogbefia, Oddoye, & Oldham, 2009), sawdust (Kwak, Jung, & Kim, those 2008) and jatropha seed cake (Pereira, 2011). Thus, in this study, we tested the ability of P. ostreatus to degrade antinutritional
factors and produce edible mushrooms using different proportions of the J. curcas seed cake as substrate. The isolate Plo 6 of P. ostreatus, which were used in this study, belong to collection of the Department of Microbiology of Federal University of Viçosa, MG, Brazil. This isolate was grown in a Petri dish containing potato dextrose agar culture medium (Merck) at pH 5.8 and incubated at 25 °C. After 7 days, the mycelium was used for inoculum production (spawn) in a substrate made of rice grains with peel ( de Assunção et al., 2012). The rice grains were cooked for 30 min in water at a 1:3 (rice grains:water, w/w). After cooking, the grains were drained and supplemented with 0.35 (g/100 g) CaCO3 and 0.01 (g/100 g) CaSO4. These grains (70 g) were packed into small glass jars and sterilized in an autoclave at 121 °C for 1 h. After cooling, each jar was inoculated with 4 agar discs (5 mm diameter) containing mycelium and incubated in the dark at 25 ± 2 °C for 15 d. The J. curcas seed cake used in this study was obtained from an industry of biodiesel (Fuserman Biocombustíveis, Barbacena, Minas Gerais State, Brazil). The proper substrate composition for optimal growth and enzyme production by P. ostreatus was chosen based on previously experiments with jatropha seed cake and different agroindustrial residues ( Da Luz, 2009).