Bimolecular optimization of cellulase production by <i>Richoderma citrinoviride</i> and <i>Aspergillus niger</i> isolates on corn cob, rice bran and sorghum bran as biomass substrates

Abstract

This work focuses on the assessment of the conditions relevant for the improvement of enzymes hydrolysis of pretreated corn cob, rice bran and sorghum bran by using Trichoderma Citrinoviride and Aspergillus niger. To achieve this, different fermentation conditions were applied to assess their effect in the optimization of cellulase production. Effects of fermentation duration, inoculation size, temperature and pH of fermentation on cellulase production were investigated. At 96 hrs of fermentation, maxim cellusale product was found to be at optimum in both organisms. Hence, 6% substrates concentration with 10 discs of 8mm inoculum size yielded maximum cellulase production in both A. niger and T. citrinoviride after 5 days of incubation. At 35ºC, A niger and T citrinoviride recorded maximum cellulase production 0.50 mg/ml in sorghum bran while 40ºC was optimum for maximum cellulase production for T, citrinoviride on corn cob. Whereas, pH 5.0 T. citrinoviride exhibits maximum cellulase production with sorghum bran 1.30 mg/ml compared to carboxymetyyl cellulose which served as control and sorghum bran 1.2mg/ml. These results highlight the potentials of T. citrinoviride as species of fungus for the industrial production of cellulase using Agricultural wastes as substrates. Cellulase yield was repressed in the presence of glucose and was induced in the presence of corn cob, rice bran and sorghum using T. citrinoviride. Cellulase yield from Corn cob, rice bran and sorghum bran differed significantly at (P<0.05) from glucose.