A carboxymethylcellulose (CMC)-degrading bacterium was isolated from soil, identified as Bacillus methylotrophicus according to the physiological properties and analyses of 16S rRNA and a partial sequence of the gyrase A (gyr A) gene, and named as B. methylotrophicus Y37. The CMCase enzyme was purified to homogeneity by 20.4-fold with 21.73% recovery using single-step hydrophobic interaction chromatography and biochemically characterized. CMCase showed a molecular weight of approximately 50 kDa as determined by SDS-PAGE. The activity profile of the CMCase enzyme exhibited optimum activity at 45 • C and pH 5.0. The activity was highly stable at alkaline pH levels. More than 90% of the original CMCase activity was maintained at relatively high temperatures ranging from 55 to 65 • C. The enzyme activity was induced by Ca 2+ , Cd 2+ , Co 2+ , K + , Mg 2+ , and Na 1+ , whereas it was strongly inhibited by phenylmethanesulfonyl fluoride and iodoacetic acid. The enzyme tolerated Hg 2+ up to 10 mM and presented hydrolytic activity towards glucan, filter paper, laminarin, and CMC but not o-nitrophenyl β-D-galactopyranoside. Kinetic analysis of the purified enzyme showed K m and V max values of 0.19 mg mL −1 and 7.46 U mL −1 , respectively. The biochemical properties of this CMCase make the enzyme a good candidate for many industrial applications.
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