Over-expression and characterization of the alkalophilic, organic solvent-tolerant, and thermotolerant endo-l,4-ß-mannanase from Bacillus licheniformis isolate THCM 3.1

Abstract

Gene encoding for endo-1,4-ß-mannanase (EC 3.2.1.78) from Bacillus licheniformis THCM 3.1 was cloned and over-expressed in pET 100/D TOPO vector. The molecular weight of the purified enzyme was about 40 kDa. This enzyme had an optimum pH of 9 and an optimum temperature of 45 0C and retained up to 77% of its activity after incubation for 48 h. The activity of the enzyme was inhibited by 1OmM Of Pb2+, Ag+, Fe3+, Sn2+, Cu2+, and EDTA. Although partially inhibited, the enzyme retained much of its activity when the reaction solution was mixed with 15% (v/v) of the organic solvents acetone, toluene, benzene, dimethyl sulphoxide, 2-propanol, acetonitrile, or cyclohexane.