Lignocellulosic Biomass for Bioethanol Recovery: A way towards Environmental Sustainability

Abstract

The increasing population and industrialization have increased the day to day demand of energy. Global warming and other climatic disasters caused due to burning of conventional fossil fuels have laid the need for an alternative and renewable fuel. Concurrently, the worldwide demand and production of bio-ethanol, a bio-based sustainable fuel is increasing continuously. Fungal saccharification of lignocellulosic biomass takes place simultaneously with the secretion of various metabolites, which function as a catalytic system to liberate soluble sugars from insoluble composite biomass. Cellulase holds a major role for converting lignocellulosic feedstock into fermentable sugar. Fungi, especially filamentous fungi preferably the Aspergillus species are known to produce cellulase. Amongst the lignocellulosic biomass, rice straw is considered as one of the most attractive materials for producing bioethanol because of its high cellulosic and hemicellulosic content, which can be hydrolyzed into fermentable sugars. However, the recalcitrant nature of the substrate imposes considerable challenges and limitations to bioethanol production. To combat these challenges, various pretreatment techniques such as chemical, physical, and physico-chemical processes are known to be effective enough to enhance the efficiency of enzymatic saccharification to make the complete process economically feasible. The present work deals with the isolation and selection of hypercellulase-producing fungal species. These species were used along with the pretreatment techniques either alone or in combination for efficient hydrolysis of rice straw to obtain the maximum amount of the released sugar.