Optimization of solid state fermentation conditions for improved production of cellulases by <i>Didymella phacea</i>

Abstract

Enzyme production by microorganisms may be improved by mutagenesis of the producing strains and/or the optimization of conditions for production. The effective and efficient use of cellulases in industrial processes has been hampered by the high cost of the enzymes which in consequence lead to high overall production costs. This study aimed at optimizing solid state fermentation conditions using affordable susbtrates and sustainable additives for improved cellulase production by Didymella phacea. Cellulase production during solid state fermentation of different lignocellulosic substrates and the effect of varying physical parameters including temperature, pH, additional supplements like nitrogen source and lactose were investigated. A 188% increase in cellulase production by D. phacea was achieved using solid state fermentation of Jatropha seed cake, incubated at 30 °C for a period of 72 hours, with an initial pH of 6, peptone at a concentration of 1 g/L, lactose at a concentration of 3.5 g/L and an additional 10% thatch grass as an additional carbon source. There was a significant difference in the increase of cellulase production before and after the optimization process ( p< 0.05). Optimization of culture conditions may be used as a quick, cheap and effective alternative to increase enzyme production.