Purification and characterization of carboxymethylcellulase isolated from a marine bacterium, Bacillus subtilis subsp. subtilis A-53

摘要

The microorganism hydrolyzing carboxymethylcellulose (CMC) was isolated from seawater, identified as Bacillus subtilis subsp. subtilis by analyses of 16S rDNA and partial sequences of the gyrA gene, and named as B. subtilis subsp. subtilis A-53. The molecular weight of the purified carboxymethylcellulase (CMCase) was estimated to be about 56kDa with the analysis of SDS-PAGE. The purified CMCase hydrolyzed carboxymethylcellulose (CMC), cellobiose, filter paper, and xylan, but not avicel, cellulose, and p-nitrophenyl-β-D-glucospyranoside (PNPG). Optimal temperature and pH for the CMCase activity were determined to be 50 C and 6.5, respectively. More than 70% of original CMCase activity was maintained at relative low temperatures ranging from 20 to 40 C after 24 h incubation at 50 C The CMCase activity was enhanced by EDTA and some metal ions in order of EDTA, K~+, Ni~(2+), Sr~(2+), Pb~(2+), and M~(2+), but inhibited by Co~(2+)and Hg~(2+).