Abstract:

Enzymatic properties of β-1,3-1,4-glucanase secreted by recombinant S. cerevisiae strain SC-βG was examined using Congo-Red method and compared with the native β-1,3-1,4-glucanase from original strain B. subtilis. Results showed that obvious differences in enzymatic properties of β-1,3-1,4-glucanase from S. cerevisiae strain SC-βG and original strain B. subtilis except substrate specificity were observed. The optimal reaction temperature was 35 ℃ for recombinantβ-1,3-1,4-glucanase and 55 ℃ for native β-1,3-1,4-glucanase. As for thermal stability, recombinantβ-1,3-1,4-glucanase remained 63.4% activity after 40 ℃ heat treatment for 20 min and 45.9% activity after 70 ℃heat treatment; in contrast, the nativeβ-1,3-1,4-glucanase was stable below 50 ℃ and its activity exhibited a significant loss after heat treatment at 60 ℃. Moreover, the optimal reaction pH for both enzymes also exhibited an obvious difference, such as pH 5.0 for recombinant β-1,3-1,4-glucanase and pH 6.5 for native β-1,3-1,4-glucanase. Similarly, the optimal pH for stability of both enzymes was 5.5 for recombinant β-1,3-1,4-glucanase and 7.0 for native β-1,3-1,4-glucanase. Therefore, the optimal reaction conditions of recombinant β-1,3-1,4-glucanase are closer to beer brewing conditions so that this enzyme should reveal better effect on beer brewing.

Key words: industrial S. cerevisiae, β-1,3-1,4-glucanase, enzymatic property