Isolation and Characterization of Saccharomyces cerevisiae from nuruk for Production of Ethanol from Maltose

Abstract

Wild-type yeast strains were isolated from nuruk, a type of microbial starter culture used for fermenting grains to produce alcoholic products, that was collected from different areas in Korea. Strains were identified based on the analysis of 18S rRNA sequences. Fifty strains shared the highest sequence similarity with Saccharomyces cerevisiae and were designated MBYK1−MBYK50. Among these S. cerevisiae isolates, MBYK45 produced 44.0 ± 0.3 g of ethanol from 200 g maltose after incubation at 30 o C for 48 h. Maximum ethanol production of 110.80 ± 0.81 g/l with productivity of 3.79 ± 0.14 g-1 l-1 h-1 was obtained at optimum culture conditions of pH (6.0), maltose (200 g/l), and temperature (35°C). This study indicates that the MBYK45 strain of S. cerevisiae, isolated from nuruk, might be suitable for traditional liquor production from malts.