Bioethanol Production by Selected Native Yeasts in Sudan

There is an increased need to replace fossil fuel by more eco-friendly alternatives such as bioethanol. The wild indigenous yeasts may hold great potential for bioethanol production economics through their high yield, substrate preference, and ethanol tolerance. In this study, four isolates of wild yeasts were analyzed for their bioethanol production when cultured in a medium containing three different carbohydrates (e.g., Dextrose, Sucrose and Starch) at 10,100, and 200g/l concentrations. The production of bioethanol was estimated using the colorimetric method. The highest growth was achieved by the local isolate from date (182×106) followed by the isolate from grape (160 × 106), both in 100g/l dextrose. The highest bioethanol yield was obtained by date isolate in 200 g/l sucrose, followed by grapes isolate in starch medium and sorghum isolate in sucrose. The commercial yeast yielded the maximum bioethanol in dextrose medium. The maximum bioethanol yield correlated with high carbohydrate concentrations. The local isolates showed a moderate tolerance for ethanol and outperformed commercial yeast in all concentrations tested. This study shed light on locally-isolated wild yeasts and reflects their greatest ability in production of bioethanol and tolerate to high concentrations of ethanol, which is a prerequisite for designing strategies for improving the performance of industrial yeasts during commercial production in large quantities.