Enhanced cellulase production through random mutagenesis of Talaromyces pinophilus OPC4-1 and fermentation optimization

Abstract

Reducing cellulase cost remains a major challenge for lignocellulose to fuel and chemical industries. In this study, mutants of a novel wild-type cellulolytic fungal strain Talaromyces pinophilus OPC4-1 were developed by consecutive UV irradiation, N-methyl-N`-nitro-N-nitrosoguanidine (NTG) and ethylmethane sulfonate (EMS) treatment. A potential mutant EMM was obtained and displayed enhanced cellulase production. Using Solka Floc cellulose as the substrate, through fed-batch fermentation, mutant strain T. pinophilus EMM generated crude enzymes with an FPase activity of 27.0 IU/mL and yield of 900 IU/g substrate. When corncob powder was used, strain EMM produced crude enzymes with an FPase activity of 7.3 IU/mL and yield of 243.3 IU/g substrate. In addition, EMM crude enzymes contained 29.2 and 16.3 IU/mL β-glucosidase on Solka Floc cellulose and corncob power, respectively. The crude enzymes consequently displayed strong biomass hydrolysis performance. For corncob hydrolysis, without supplement of any commercial enzymes, glucose yields of 591.7 and 548.6 mg/g biomass were obtained using enzymes produced from Solka Floc cellulose and corncob powder, respectively. It was 553.9 mg/g biomass using the commercial enzyme mixture of Celluclast 1.5 L and Novozyme 188. Strain T. pinophilus EMM was therefore a potential fungus for on-site enzyme production in biorefinery processes.