Comparative performance of different yeast strains in the production of bioethanol using simultaneous liquefaction saccharification and fermentation (SLSF)

The performance of a hybrid of Saccharomyces cerevisiae and Saccharomyces paradoxus (Yeast B) compared with an industrial strain of S. cerevisiae (Yeast A) was studied.  The two strains of yeasts: Yeast A obtained from the Bioresources Development Centre, National Biotechnology Development Agency Ogbomosho and Yeast B obtained from Scotch Whisky Research Laboratory in Edinburgh, Scotland (Strain 63M) were studied using the SLSF method for bioethanol production at various initial starch concentrations (20, 30 and 50%). The cassava starch used was extracted from Tropical Manihot esculenta (TME 419) cassava strain while the SLSF method for bioethanol production was initiated by adding granular starch hydrolysing enzyme with the yeast strains into the starch solutions at room temperature. The results obtained showed that Yeast B has higher bioethanol yield and tolerance generating 70.34, 87.34 and 120.53 ml/L compared to the Yeast A which produced 63.4, 72.73 and 112.6 ml/L at 20, 30 and 50% starch concentrations respectively. The study suggests that the hybrid strain of S. cerevisiae and S. paradoxus out performs the industrial strain and can favorably substitute or displace the industrial strains for bioethanol production.   Key words: Bioethanol, cassava, fermentation, hybrid, simultaneous liquefaction saccharification and fermentation (SLSF), yeast, Saccharomyces cerevisiae, Saccharomyces paradoxus.