Bioethanol Production from Jowar Husk (Sorghum bicolor) Using Indigenous Cellulase-Producing Yeast Geotrichum candidum.
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Abstract
Growing interest in sustainable biofuels has encouraged the exploration of agricultural residues as alternative energy resources. In this study, indigenous yeast strains were isolated from agro-organic substrates and evaluated for their ability to convert lignocellulosic biomass into bioethanol using jowar husk (Sorghum bicolor) as the feedstock. Soil, compost, fruit waste, and sugarcane bagasse samples were collected from Raipur, Chhattisgarh, and screened for yeast abundance and cellulolytic potential. Marked variation in yeast populations was observed, with fruit waste and compost supporting comparatively higher counts. Among the isolates obtained, a cellulase-producing strain identified as Geotrichum candidum demonstrated superior enzymatic performance based on morphological, microscopic, and molecular analyses. Alkali-pretreated jowar husk was subjected to enzymatic hydrolysis using crude cellulase derived from this isolate, resulting in the release of 45–70 g L⁻¹ fermentable sugars. Subsequent fermentation of the hydrolysate produced 18–22 g L⁻¹ ethanol after 72 hours, corresponding to a conversion efficiency of approximately 0.40–0.42 g g⁻¹ of fermentable sugars. Product confirmation was carried out using FTIR spectroscopy, which showed characteristic absorption bands associated with alcohol functional groups, while HPLC analysis revealed a prominent ethanol peak, indicating successful fermentation. The results support the potential of agro-waste-derived yeasts and jowar husk as a viable combination for bioethanol production and highlight the relevance of regionally available biomass in sustainable bioenergy strategies.