BIOCONVERSION OF HEMICELLULOSIC FRACTION OF PERENNIAL KANS GRASS (SACCHARUM SPONTANEUM) BIOMASS TO ETHANOL BY PICHIA STIPITIS: A KINETIC STUDY

Ethanol is a promising alternative energy source for the limited crude oil and can be produced from abundantly available lignocellulosic biomass. Utilization of acid hydrolysate of Kans grass (Saccharum spontaneum), a perennial grass native to South Asia, has been investigated for ethanol production. The dilute acid treatment was applied to hydrolyze the Kans grass biomass for releasing maximum hemicellulosic sugars. The aim of this work was to develop a fermentative system utilizing Kans grass hemicellulose acid hydrolysate as a substrate for ethanol production by Pichia stipitis. It was found that 74% of xylose was converted to ethanol with a yield of 0.429 gp gs(-1) and productivity of 0.231 gp l(-1) h(-1). The appropriate mathematical models for cell and ethanol production rate have been developed to explain theoretically the bioconversion of Kans grass hemicellulose acid hydrolysate to ethanol and validated statistically with the experimental results carried out in the laboratory. The present study revealed that the degradation of sugar, activation and inhibition of cells, and ethanol production were strictly coupled during the bioconversion process of hemicellulosic fraction of Kans grass to ethanol.