Bioethanol Production from xylose using Pichia stipitis

Abstract

Bioethanol is the ethanol produced from biological sources through biological processes like the fermentation of sugars, molasses, etc. It primarily uses in food, pharmaceutical, and biofuel applications. The production of bioethanol from sugar is costly. The most widely used, less expensive alternative raw material is lignocellulosic biomass. The readily available lignocellulosic materials in Indian conditions are sugarcane bagasse, the fibrous residue obtained after extracting the juice from sugar cane. Bioethanol production from the sugar cane bagasse is a complex process and requires multiple steps due to its chemical complexities. The significant steps in this process are feed preparation, biomass pretreatment, cellulose hydrolysis, fermentation of hexoses, separation using distillation, dehydration and effluent treatment. As the sugarcane bagasse contain hemicellulose and cellulose, it needs to be hydrolysed by biomass pretreatment, utilising enzymes or acids, to fermentable sugars. The solid fraction which contains cellulose hydrolysate is fermented and converted into ethanol. The liquid fraction which contains pentose sugars is fermented out in a separate unit using microorganisms that ferment pentoses and hexoses.