Bioethanol production from four abundant Indian agricultural wastes

ABSTRACT

Lignocellulose feedstocks are promising second-generation sources of ethanol biofuel. They include massive amounts of agricultural waste generated in India, much of which is currently burnt (exacerbating major pollution problems), but could potentially be fermented. To assist efforts to realize this potential, four abundant kinds of Indian agricultural residues (sugarcane bagasse and straw from rice, sweet sorghum and millet) were hydrolyzed via a dilute-acid method and fermented at 27 °C, using the white-rot fungus Trametes versicolor as a biocatalyst. The total carbohydrate contents of the agriculture wastes were analyzed, as well as soluble sugar contents of the hydrolysates at the start and end of the fermentations; their ethanol yields and activities of the key enzymes aldehyde dehydrogenase and pyruvate decarboxylase were also measured. Results show that ca. 85–90% of the fermentable sugars were used for ethanol production, and the enzyme activities are consistent with the observed yields. The findings indicate a great potential for ethanol production from Indian agricultural waste.

KEYWORDS:

• Agricultural residues
• biomass
• dilute acid pre-treatment
• enzymes
• ethanol production
• Trametes versicolor

Acknowledgements

Thanks are due to the Tryggers Foundation for grants (KLR, AD, MH, AS) and Energimyndigheten (AS). Thanks are also due to Dr. Junko Tagashi-Smith, UPSC and Cell Wall Lab, for valuable analysis of total sugars. In addition thanks are due to the Linnaeus-Palme Exchange Program for Teachers and the University of Agricultural Sciences, GKVK Campus, Bangalore, India, for grants (HKM).

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Carl Tryggers Stiftelse för Vetenskaplig Forskning [grant number CTS 10:337]; Carl Tryggers Stiftelse för Vetenskaplig Forskning [grant number CTS 11:418]; Linnaeus-Palme Foundation [grant number LPF 12:100] and Microbiorefine (Energimyndigheten 2013-06259).