Optimizing Bio-ethanol Production from Striga hermonthica Using Yeast (Saccharomyces cerevisiae) as a Fermenting Agent

Abstract

Global warming, urban pollution and depletion of fossil fuels have been driving for looking alternative energy sources, especially those derived from biomass. Production of bio-ethanol from lingocellulosic materials is providing a long-term sustainable for fuel supply. Striga hermonthica, a parasitic weed plant is one of cheap source of lignocellosic materials to serve as feedstock for bio-ethanol production. With the objective of evaluating its potential for bio-ethanol production, different concentrations (10g, 20g, 30g, and 40g) of Striga hermonthica treated with 1% diluted sulfuric acid and untreated were subjected to batch fermentation for 16 days with 0.5% and 1% yeast inoculums. Percent of bio-ethanol production, cell density and reducing sugars were measured at an interval of 4 days starting from the beginning. Results of these study showed that ethanol production was observed starting from the 4th day of fermentation, but its amount peaked 28.05% from 40g substrate with 1% inoculum on the 12th day of fermentation, and declined on 16th days (20.24%) from the same substrate concentration. Pretreated substrate showed significantly higher ethanol production than untreated. In agreement with ethanol production, cell density and reduction in reducing sugar were observed in the same pattern. Compared ethanol production between untreated substrates yield of 21.31%, and treated substrates yielded of 28.05%. Overall, this study showed that acid pre-treatment, inoculum concentration, fermentation period and substrate concentration affect the amount of bio-ethanol production. Finally, it can be concluded that the production of bioethanol from Striga hermonthica is economically and environmentally viable. Extensive use of this harmful weed for bioethanol production may have twofold advantages, viz. reduction of its negative impact on crop productivity and generation of bio-ethanol.