Bioconversion of sugarcane tops to bioethanol and other value added products: An overview

The increasing use of non-renewable resources and its continuous depletion has become a major concern nowadays. The production of renewable fuels from agricultural lignocellulose waste is sustainable and economically feasible. Sugarcane top is one of the most abundant lignocellulosic biomasses in India. More conveniently, it is burned in the field being in large quantity and the high-cost involved in its collection and transportation. The pretreatment process is one of the cost intensive steps in the bioethanol production, owing to the manpower and expensive chemicals requirement to separate cellulose, hemicellulose and lignin from lignocellulosic biomass. In recent times, the advent of novel recombinant carbohydrate-active enzymes from different microbial sources by genetic manipulation has led to great advances in saccharification of pretreated biomass leading to higher production of bioethanol. The multi-enzyme complexes called cellulosomes are capable of hydrolyzing cellulose and hemicellulose. This study is aimed at production of xylan, bioethanol and other value-added products from sugarcane tops. Isolation, separation and characterization of xylan, cellulose and lignin from sugarcane tops can be most efficient industry oriented approach due to their xylo-oligosaccharides or alternative substrate, bioethanol and oil based petro-chemical applications. The saccharified hydrolysate can be used for bioethanol production by fermenting with Saccharomyces cerevisiae. Xylooligosaccharides can also be produced by enzymatic hydrolysis of xylan extracted from agro-waste and have applications in controlling blood sugar level, boosting immunity, improving intestinal function and reducing fatigue. Xylan can be utilized for the production of xylo-oligosaccharides, food coating, packaging films and other pharmaceutical applications. Lignin is mainly used as a rubber intensifier, polyolefin and rubber packing. It is also used in making cement, composite materials, unsaturated polyester and vinyl ester as filler and co-monomer.