Cellulase production by Penicillium expansum MDFS2 during solid-state fermentation of rice straw, rice bran and wheat straw residues

Abstract

Production of fungal cellulase was performed by the isolate of Penicillium expansum MDFS2 on rice straw, rice bran, and wheat straw under solid-state fermentation. The greatest potential growth was detected using rice bran as the carbon source substrate. On the fifth day of fermentation, filter paperase, carboxymethyl cellulase, and β-glucosidase obtained their maximal activities of 4.91 U/g substrate, 36.51 U/g substrate, and 12.21 U/g substrate, respectively. The optimum temperature for filter paperase was reported at 40 °C, whereas carboxymethyl cellulase and β-glucosidase were optimally active at 50 °C. Filter paperase and carboxymethyl cellulase showed maximum activity at pH 5.0. However, β-glucosidase proved to be maximally active at pH 6.0. According to the thermal stability results, all the three components of the cellulolytic enzyme complex proved to be less thermally resistant at 60 °C, as compared to 50 °C. β-glucosidase and carboxymethyl cellulase depicted the highest and the lowest thermal resistance, respectively. β-glucosidase and filter paperase stored for one week at -20 °C proved to be the most and least stable enzymes, respectively. It is hoped that current research findings will help in the cost-effective production of industrially important cellulases using agro-industrial by-products as fermentation substrates.