Study On Cellulase Production And Enzymatic Conversion From Cassava Residues

Cassava residues (CR) is cassava ethanol factory waste, containing a certain amount of cellulose, hemicellulose and pectin substances. In this paper, we studied the utilization of CR.Crude cellulase enzyme was manufactured using the plant fiber cellulose wastes CR by strains. The medium of cellulase production was studied by single factor experiments, orthogonal experiment and response surface analysis methods. When the CR diameter was less than 0.425 mm, the seed culture time was 24h and preculture was added into production media with a ratio of 20%. The medium composition is as follows:0.35 g (NH4) 2HPO4,0.3 g KH2PO4,3 g wheat bran,7 g CR and then cellulase production was performed with a ratio of material to water 1:1.5 at 30℃, initial pH 6.5. We obtained crude cellulase enzyme (56.37 IU/g dry material) by Trichoderma GV with the solid state fermentation.When the corncob residues (CCR) diameter was 0.15-0.30mm, the medium composition is as follows:0.35 g (NH4) 2HPO4,7 g wheat bran,3 g CCR and then cellulase production was performed with a ratio of material to water 1:2 at 30℃, initial pH 6.5. We obtained crude cellulase enzyme (FPA was 26.18 IU/g dry material,β-glucosidase activity was 75.10 IU/g dry material) by Penicillium decumbens JUA10-1 with solid fermentation.When CR, ammonium sulfate, wheat bran and inoculum size were 3%,0.5%,9% and 10% respectively, cellulase activity was 3.03 IU/ml, andβ-glucosidase activity was 1.40 IU/ml by Penicillium decumbens JUA10-1 with liquid fermentation in 500-ml flask with 50 ml culture.CR was hydrolyzed by cellulase and its hydrolysate was analyzed. It was found that when the substrate concentration was 20%, glucose yield reached 88% at 96h using cocktail cellulase from mixure of P. decumbens JUA10-1 and the enzyme of Aspergillus NIP35 with solid state fermentation.