Prospects for Bio-Industrial Application of an Extremely Alkaline Mannanase From Bacillus subtilis subsp. inaquosorum CSB31.

Mannan-degrading enzymes have been growing interest in bio-industrial applications, such as the pulp and paper, food, and pharmaceutical industries. In this study, an extremely alkaline mannanase (MnB31) is produced by Bacillus subtilis subsp. inaquosorum CSB31. MnB31 is purified to 17.92-fold with a 21.51% yield and specific activity of 1,796.13 U mg-1 by anion-exchange and gel filtration column chromatography. The biochemical characterization of MnB31 is performed, and the results are as follows: molecular weight of ≈47 kDa with an optimum temperature of 60 °C and pH of 12.5. The enzyme is strongly activated by Co2+ , Mn2+ , Na+ , and K+ , and inhibited by Zn2+ , Ni2+ , and Mg2+ . Halo-tolerance (10% NaCl), urea stability (3 M), and protease resistance are also observed. The kinetic parameters of MnB31 are found to be Km of 0.043 mg ml-1 , and Vmax of 1,046 ± 3.605 U mg-1 , respectively. In addition, the thermodynamical parameters are investigated; the activation energy (Ea ) is found to be 31.36 kJ mol-1 with a Kcat value of 156.9 × 104 s-1 , ΔH (28.59 kJ mol-1 ), ΔG (42.38 kJ mol-1 ), ΔS (-41.39 J mol-1 K-1 ), Q10 (1.40), ΔGE-S (-8.697 kJ mol-1 ), and ΔGE-T (-48.22 kJ mol-1 ). These results suggest that MnB31 has potential bio-industrial application, due to its greater hydrolytic efficiency and feasibility of enzymatic reaction.

Understanding ß-mannanase from Streptomyces sp. CS147 and its potential application in lignocellulose based biorefining.

Hydrolytic enzymes such as cellulase and hemicellulase have been attracted in lignocellulose based biorefinery. Especially, mannanase has been a growing interest in industrial applications due to its importance in the bioconversion. In this study, an extracellular endo-ß-1,4-D-mannanase was produced by Streptomyces sp. CS147 (Mn147) and purified 8.5-fold with a 43.4% yield using Sephadex G-50 column. The characterization of Mn147 was performed, and the results were as follows: molecular weight of ∼25 kDa with an optimum temperature of 50°C and pH of 11.0. The effect of metal ions and various reagents on Mn147 was strongly activated by Ca(+2) but inhibited by Mg(+2) , Fe(+2) , hydrogen peroxide, EDTA and EGTA. Km and Vmax values of Mn147 were 0.13 mg/mL and 294 µmol/min mg, respectively, when different concentrations (3.1 to 50 mg/mL) of locust bean gum galactomannan were used as substrate. In enzymatic hydrolysis of heterogeneous substrate (spent coffee grounds), Mn147 shows a similar conversion compared to commercial enzymes. In addition, lignocellulosic biomass can be hydrolyzed to oligosaccharides (reducing sugars), which can be further utilized for the production of biomaterials. These results showed that Mn147 is attractive in quest of potential bioindustrial applications.