A novel low-molecular weight alkaline mannanase from Streptomyces tendae

A novel, low-molecular weight, alkaline mannanase from Streptomyces tendae (MnSt) was purified to homogeneity and biochemically characterized. The extracellular mannanase was purified with 26.3% yield using a Sepharose Cl-6B column. The molecular mass of MnSt was approximately 24 kDa. MnSt was stable over a broad pH range (5 ∼ 12.5), was thermally stable at 60°C, and functioned optimally at 50°C and a pH of 12.0. MnSt had K_m and V_max values of 0.05 ± 1 mg/mL and 439 ± 0.5mmol/min, respectively, using bean gum galactomannan as a substrate. The N-terminal sequence of MnSt was GWSVDAPYIAXQPFS. Thin layer chromatography (TLC) analysis of the MnSt hydrolysis products suggested that the major oligosaccharide produced was mannobiose. MnSt activity was remarkably affected by metal ions, modulators, chelators, and detergents. MnSt was simple to purify, had high thermal stability, was stable over a broad pH range, and produced mannooligosaccharides. MnSt has high potential for use as an industrial biocatalyst, particularly as a bio-bleaching agent or for oligosaccharide production.