Characterization of mannanase from Bacillus sp., a novel Codium fragile cell wall-degrading bacterium

Seaweeds are considered as a health food partly due to the polysaccharide composition of the cell wall. Because conventional extraction methods have low yields and lead to environmental pollution, enzymatic methods have been proposed. In this study, a new strain of Bacillus sp. was isolated from cattle feces that produced a mannanase, a polysaccharide-degrading enzyme active against the green seaweed Codium fragile. The purified 39-kDa mannanase exhibited maximum activity at 55 °C and pH 6.0, and maintained its catalytic activity stably at temperatures up to 60 °C and at a broad pH range (5.0-11.0). Enzymatic activity was slightly enhanced by Cu²⁺ and Na⁺ but strongly inhibited by Fe²⁺, Ag⁺, and EDTA. The mannanase showed the highest specificity to the inexpensive substrates such as konjac powder and locust bean gum, and efficiently released various manno-oligosaccharides. This novel mannanase can thus be applicable in the food, feed, and pulp industries.