Optimization for β-Mannanase Production of a Psychrophilic Bacterium, Flavobacterium sp.

Abstract

   We found that a psychrophilic bacterium, Flavobacterium sp., characterized in this study, has a β-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°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°C. When the reaction was done at 10°C, the enzyme showed 25% of the optimal activity. The β-mannanase preparation efficiently hydrolyzed guar gum, locust bean gum, and glucomannan as well as β-mannan.