The treatment of oil palm empty fruit bunch fibre for subsequent use as substrate for cellulase production by Chaetomium globosum Kunze

Abstract

The feasibility of using treated oil palm empty fruit bunch (OPEFB) fibre as a substrate for cellulase production by Chaetomium globosum Kunze was studied using a shaking flask fermentation system. The use of 2-mm chemically untreated OPEFB fibre increased cellulase production by about two times compared to 10-mm fibre. The effect of the different chemicals (NaOH, HCl, HNO 3, EDA and EDTA) on the 2-mm fibre was also investigated. Treatment with these chemicals significantly ( P < 0·05) increased the cellulose and reduced the lignin contents. Fermentation using OPEFB fibre treated with HNO 3(0·5% v/v) gave the highest cellulase production and this was related to its high cellulose content. Cellulase production increased further when autoclaved (121°C, 15 psi for 5 min), chemically treated OPEFB fibre was used. When autoclaved 2-mm OPEFB fibre treated with HNO 3 was used as a substrate, the maximum FPase activity and yield obtained were 0·95 U ml −1 and 120·7 U g −1 cellulose, respectively. The cellulase produced by C. globosum contained a high proportion of β-glucosidase. The ratio of specific activity of β-glucosidase to FPase was about 8. The production of all three major components of cellulase (endoglucanase, cellobiohydrolase and β-glucosidase) using pretreated OPEFB fibre were about three times higher than those obtained in fermentations using pure cellulose (Avicel and carboxymethylcellulose).