Isolation and characterization of bioethanol producing wild yeasts from bio-wastes and co-products of sugar factories

Abstract Purpose Yeasts are widely used for the production of bioethanol from biomasses rich in sugar. The present study was aimed at isolating, screening, and characterizing fermentative wild yeast recovered bio-waste co-products Ethiopian sugar factories using sugarcane molasses as a substrate. Method yeasts were identified according to their cellular morphology D1/D2 ITS1-5.8S-ITS2 rDNA sequencing. Analysis ethanol by-product concentration done by HPLC equipped with UV detector. Higher alcohols, acetaldehyde, methanol analyzed GC-MS flame ionization detector (FID). Result Seven strains ( Meyerozyma caribbica MJTm3, MJTPm4, SHJF, Saccharomyces cerevisiae TA2, Wickerhamomyces anomalus MJTPm2, 4m10, HCJ2F) found tolerant 18% (v/v) ethanol, whereas one strain MJTm3 tolerated 20%. These also showed tolerance 45°C, 50% sugar, pH 2–10. produced 12.7% alcohol an actual 26 g L ?1 , yield 47%, 78% theoretical yield, productivity 0.54 h 30 °Brix 48 incubation under laboratory scale. Based on variable time optimization (OVAT), optimal parameters maximum initial 5.5, 35 °Brix, 30°C, 15% inoculum size, 150 rpm, 4 di-ammonium phosphate supplement, incubation. Under these optimum conditions, 14% alcohol, 42 concentration, 69% 89% 0.88 obtained. Conclusion results indicated that M. should further be evaluated, optimized, improved industrial due its fermentation potential.