Characterization of the starch degradation activity from newly isolated Rhizopus oryzae WCS-1 and mixed cultures with Saccharomyces cerevisiae for efficient ethanol production from starch

초록

A starch degrading fungi was isolated from nuruk, a Korean traditional starter culture made with wheat flour. This newly isolated fungi was identified as Rhizopus oryzae WCS-1 via internal transcribed spacer region sequencing. Enzymatic assays for starch degradation activities indicated an optimum temperature and pH of 55A degrees C and pH 4.0, respectively, using partially purified enzymes from R. oryzae WCS-1. Mixed cultures with S. cerevisiae CEN-PK 2-1D, L2612, BY4742, and D452-2 were performed. S. cerevisiae CEN-PK 2-1D has a maltose utilization pathway and showed the highest ethanol production rate with low maltose concentrations. Addition of 5 mM NaCl to mixed cultures of R. oryzae WCS-1 and S. cerevisiae CEN-PK 2-1D resulted in 21 and 33% improvements in the starch consumption rate and the ethanol production rate, respectively, because Na+ stimulated the starch degradation activity of partially purified enzymes from R. oryzae WCS-1.

키워드