Optimization of catalase production and purification and characterization of a novel cold-adapted Cat-2 from mesophilic bacterium Serratia marcescens SYBC-01

Abstract

Maximum catalase production by mesophilic bacterium Serratia marcescens SYBC-01 was obtained by an optimization of culture medium and conditions. A novel cold-adapted catalase from the strain was purified and characterized. The Cat-2 without peroxidase activity was a homodimer with a molecular mass of 154 kDa, consisting of two identical subunits of about 70 kDa. Its apparent Km and Vmax value were 29.7 mM and 80,925 U/mg of protein, respectively. The Cat-2 exhibited maximal activity at pH 7.0, being relatively stable in alkaline conditions. The enzyme was most active at approximately 20°C and had 73.8% activity at 0°C. After incubation at 60°C for 60 min, the enzyme still maintained 75% of its initial activity. The Cat-2 displayed relatively higher thermostability compared to that of other cold-adapted and some mesophilic catalases.