Optimization for beta-mannanase production of a psychrophilic bacterium, Flavobacterium sp.

We found that a psychrophilic bacterium, Flavobacterium sp., characterized in this study, has a beta-mannanase (EC 3.2.1.78) activity in the culture medium. The mannanase activity was the highest in the culture medium, containing 1.0% (w/v) guar gum (as a carbon source), 0.3% (NH4)2SO4 (as a nitrogen source), and 0.06% (w/v) yeast extract, of five-days cultivation at 4 degrees C. No mannanase activity was found in the medium containing a monosaccharide or a disaccharide as a carbon source, although the psychrophile could use them. The enzyme activity was found only when the bacterium was cultured in the medium containing a polysaccharide. The enzyme preparation showed a single activity band on a washed gel of SDS-PAGE. The optimal temperature for the enzyme activity was 35 degrees C. When the reaction was done at 10 degrees C, the enzyme showed 25% of the optimal activity. The beta-mannanase preparation efficiently hydrolyzed guar gum, locust bean gum, and glucomannan as well as beta-mannan.