Particle geometry affects differentially substrate composition and enzyme profiles by Pleurotus ostreatus growing on sugar cane bagasse

The growth of Pleurotus ostreatus was analyzed on three particle sizes of sugar cane bagasse: 0.92mm and1.68mm in diameter, in addition to heterogeneous fibers (average 2.9mm in diameter). Specific growth rate on heterogeneous particles was lower (μ=0.043h^-1), although soluble protein production was maximal (809μg/g dry wt). Higher μ values were reached on the other two particles sizes (0.049-0.05h^-1) with less soluble protein (500μg/g dry wt). Xylanases and laccases were favored in heterogeneous particles; while the highest selectivity for xylanases over cellulases was observed in 1.68mm particles, corresponding with the maximal hemicellulose breakdown. Lignin and cellulose were preferentially degraded in smallest particles. This study shows that the geometrical ratio, shape and size of sugar cane bagasse fibers strongly influence packing density for SSF substrate, with an impact in the production of extracellular enzymes, growth rates and composition changes in substrate.