Coimmobilization of glucose oxidase and catalase on microbial cells

Abstract

For the study of glucose oxidase and catalase coimmobilization system, enzymes were obtained from penicillium species and Strain itself was reused as immobilizing matrix. To separate glucose oxidase and catalase after $(NH_4)_2SO_4$ fractionation, DEAE-cellulose column was used and its activity yield were 54\% and 34\%, respectively. Both two enzymes were immobilized on matrix cell prepared with 2.5\% (w/v) glutaraldehyde for 12hrs. In the determination of efficiencies of glucose oxidase and catalase among dual, mixed and soluble systems, dual immobilizing system was superior to that of soluble and mixed type. And it was observed that an increase in the activity ratio of CAT/GOD, efficiency of catalase increases and leads to lowering the efficiency of glucose oxidase. In comparison of pH profiles, dual and mixed types showed more broad maximum pH range than the soluble system and in varying CAT/GOD ratio of dual system, the higher the CAT/GOD ratio showed the more broad maximum activity profile. In comparison of apparent Km of GOD only and CAT/GOD = 10, they were $7.1\times10^{-2}$ and $5.1\times10^{-2}$M. And with activation energy in temperature effect, glucose oxidase and catalase were 3.98 and 2.98 Kcal/mole. These difference comes from the diffusional limitation of $O_2$, one of the substrate of oxidase, between two types of enzymes. In the continuous packed bed reactor system, Kd, deactivation rate constant, of GOD only and CAT/GOD = 10 were 0.0112 and $2.17\times10^{-3}(hr^{-1})$. In the effect of 7, the space time, the point of $O_2$ limitation is 5.55 (g.hr/l) in both CAT/GOD = 1 \& 10. In the effect of $O_2$ concentration to reduce the $O_2$ diffusion limitation, it was shown that at low $7(<5.55),\; O_2$ concentration in the feed does not affect on the reaction rate, but, at high space time, more $O_2$ concentration in the feed leads to relatively high $O_2$ consumption in both CAT/GOD = 1 \& 10.