Effect of some cations on the glucose oxydase biosynthesis of Aspergillus niger 9.4

Abstract

The glucose oxydase enzyme (GOx) (EC  1.1.3.4)  binds  to  beta-D-glucopyranose  (a hemiacetal form of the six-cacbon sugar glucose) and aids in breaking the sugar down into its metabolites. GOx is a dimeric protein that catalyzes the oxidation of  beta-D-glucose into Dglucono - 1,5-  lactone  (which  then  hydrolyzes  to gluconic  acid) using  molecular  oxygen  and releasing hydrogen peroxide. GOx can be used in theremoval of either glucose or oxygen from foodstuffs in order to improve their storage capability.

GOx can be biosynthesed by fungi Aspergillus nigerand Penicillium. The effect of various cations,  such  as  Fe²⁺ , Cu²⁺, Zn²⁺, Mn²⁺  and Co²⁺ on  the  simultaneous  production of glucose oxidase and catalase by Aspergillus niger 9.4 were investigated. Among the five cations, Zn²⁺ caused negative effect on GOx biosynthesis, two ions Fe²⁺ and Co²⁺ had positive influences on GOx biosynthetic process. The mutual influences between Fe²⁺ and Co²⁺ on GOx synthesis were also studied according to applied mathematic plan of Box -Wilson. In the medium, which was added FeSO₄ (0.027 g/l) and CoCl₂ (0.042 g/l) GOD enzyme activity (612.42 U/gr of biomass) was much higher than the sample with individual ionFe²⁺ or Co²⁺ (maximum of GOD enzyme activity reached 290.77U/gr and 278.4 U/g).