High-level production of ß-1,3-1,4-glucanase by Rhizomucor miehei under solid-state fermentation and its potential application in the brewing industry.

ABSTRACT

AIMS: To improve the ß-1,3-1,4-glucanase production by Rhizomucor miehei under solid-state fermentation (SSF) for industrial application. METHODS AND RESULTS: The fermentation conditions for ß-1,3-1,4-glucanase production by R. miehei CAU432 under SSF were optimized using a 'one-factor-at-a-time' method. Under the optimized fermentation conditions, viz. oatmeal (0·45-0·9 mm) as sole carbon source, 5% (w/w) peptone as sole nitrogen source, initial moisture of 80% (w/w), initial culture pH of 5·0, incubation temperature of 50°C and incubation time of 6 days, the highest ß-1,3-1,4-glucanase activity of 20,025 U g(-1) dry substrate was achieved, which represents the highest yield for ß-1,3-1,4-glucanase production ever reported. The crude enzyme was extracted and purified to homogeneity with a purification fold of 4·6 and a recovery yield of 9·0%. The addition of the purified ß-1,3-1,4-glucanase in mash obviously reduced its filtration time (24·6%) and viscosity (2·61%). CONCLUSIONS: The optimal fermentation conditions for maximal ß-1,3-1,4-glucanase production under SSF was obtained, and the enzyme was suitable for application in the malting process. SIGNIFICANCE AND IMPACT OF THE STUDY The high production yield and excellent capability of the enzyme may enable it great potential in industries, especially in brewing industry.