Novel process for the production of cellulolytic enzymes

Abstract

A novel process for the production of extracellular carboxymethylcellulase (CMCase) and xylanase by fermentation under nonaseptic or nonsterile conditions is described. The fermentation process is carried out under very acidic conditions of pH 2.0 by using a acidophilic cellulolytic fungus. Microbial contamination is avoided or minimized to an insignificant level under this acid pH condition. The culture medium for this production consists of a carbon source from cellulosics or lignocellulosics, such as Na–CMC, xylan, Avicel cellulose, cellulose powder, α‐cellulose, sawdust, etc., or a mixture of the forementioned together with simple ingredients such as (NH₄)₂SO₄, K₂HPO₄, MgSO₄ and NaNO₃. The fermentation is carried out at room temperature (28–30°C), under aerobic conditions, and without controlling the pH. The CMCase and xylanase produced are stable under very simple storage conditions, such as in the fresh culture medium not containing the substrate for a period of 3 days, at any temperature from 0 to 30°C. These extracellular enzymes have an optimum pH around 3, with the best range of pH from 2.0 to 3.6, for any temperature between 15 and 60°C. The optimum temperatures are 55°C for CMCase activity and 25–50°C for xylanase activity, at any pH between 2.0 and 5.2. The apparent Michaelis constants Km are 2.6 and 1.5 mg/mL for CMCase and xylanase of the culture filtrate, respectively.