Production, puri cation, and characterization of a thermo-alkali stable andmetal-tolerant carboxymethylcellulase from newly isolatedBacillusmethylotrophicusY37

Abstract

A carboxymethylcellulose (CMC)-degrading bacterium was isolated from soil, identi ed asBacillus methy-lotrophicusaccording to the physiological properties and analyses of 16S rRNA and a partial sequence of the gyrase A(gyrA) gene, and named asB. methylotrophicusY37. The CMCase enzyme was puri ed to homogeneity by 20.4-fold with21.73% recovery using single-step hydrophobic interaction chromatography and biochemically characterized. CMCaseshowed a molecular weight of approximately 50 kDa as determined by SDS-PAGE. The activity pro le of the CMCaseenzyme exhibited optimum activity at 45◦C and pH 5.0. The activity was highly stable at alkaline pH levels. Morethan 90% of the original CMCase activity was maintained at relatively high temperatures ranging from 55 to 65◦C.The enzyme activity was induced by Ca2+, Cd2+, Co2+, K+, Mg2+, and Na1+, whereas it was strongly inhibited byphenylmethanesulfonyl uoride and iodoacetic acid. The enzyme tolerated Hg2+up to 10 mM and presented hydrolyticactivity towards glucan, lter paper, laminarin, and CMC but noto-nitrophenyl-D-galactopyranoside. Kinetic analysisof the puri ed enzyme showed Kmand Vmaxvalues of 0.19 mg mL1and 7.46 U mL1, respectively. The biochemicalproperties of this CMCase make the enzyme a good candidate for many industrial applications.