PRETREATMENT AND HYDROLYSIS OF EUCALYPTUS FOR BIOBUTANOL PRODUCTION USING CLOSTRIDIUM SP. G10

Abstract

The primary objective of this study was to optimize the pretreatment and hydrolysis of eucalyptus for the cultivation of Clostridium sp. G10, a laboratory-isolated strain. Optimal alkali pretreatment conditions were determined to be 0.6 M NaOH at 121°C and 15 psi for 20 minutes, yielding a reducing sugar concentration of 11.91 g/L. Subsequent cellulose hydrolysis using ACCELERASE® 1500 (2000 endoglucanase U/g eucalyptus) for 24 hours further increased the reducing sugar concentration to 15.53 g/L. Eucalyptus hydrolysate was then utilized as a carbon source for Clostridium sp. G10 cultivation. In T6 medium supplemented with 50 g/L glucose, the maximum concentration of acetone-butanol-ethanol was 2.7 g/L. When T6 medium was supplemented with eucalyptus hydrolysate (50 g/L reducing sugar equivalent), the solvent concentration was found at 1.21 g/L. The results clearly indicate that the type of medium significantly impacts the production of acetone, butanol, and ethanol by Clostridium sp. G10. While eucalyptus hydrolysate can serve as a suitable carbon source, further optimization of hydrolysis conditions is necessary to achieve higher reducing sugar concentrations. Additionally, the removal of fermentation inhibitors from the hydrolysate is crucial for enhancing the efficiency of acetone-butanol-ethanol fermentation.