Optimization of bioethanol production using stress-tolerant yeast strains isolated from household alcoholic beverages (Tella, Tej, and Areke) and molasses (as substrate)

Abstract

<ns3:p>Background Yeast strains that are tolerant to several environmental stresses are extensively employed to produce bioethanol from sugar-rich feedstock. Bioethanol production efficiency in Metehara and Fincha Sugar Factories (the two major sugar factories in Ethiopia) is 50% lower than that of similar factories in other parts of the world. Methods In our previous research findings, five wild indigenous strains of multi-stress tolerance yeast were isolated from traditional fermented alcoholic beverages (Tella, Tej, and Areke) in Ethiopia to the purpose of evaluate their potential use for bioethanol using sugarcane molasses as a substrate. Result The optimal parameters for maximum ethanol production were pH of 4.5, 25°Brix, 30°C, 4.0 g/l ammonium sulfate, supplement with yeast extract, and 72 h of incubation period. Under these optimum conditions, 13.13 ± 0.08% (v/v) ethanol was obtained. The yield of hydrous and anhydrous bioethanol from fermented molasses samples were produced at 94.20<ns3:italic>–</ns3:italic>95.60% (v/v) and 99.05<ns3:italic>–</ns3:italic>99.56% (v/v), respectively. Conclusion According to this finding, <ns3:italic>Saccharomyces cerevisiae</ns3:italic> isolate MUT15, <ns3:italic>Saccharomyces cerevisiae</ns3:italic> isolate MUT18F<ns3:bold>, </ns3:bold> and <ns3:italic>Saccharomyces cerevisiae</ns3:italic> isolate R9MU strains have been good candidates for production of industrial bioethanol.</ns3:p>