Fermentative production of glucose oxidase from Aspergillus niger NCIM 545

Glucose oxidase (β-D-glucose: oxygen-oxidoreductase, EC 1.1.3.4) is a flavin adenine dinulceotide (FAD) dependent glycoprotein catalyzing the oxidation of β-D-glucose to glucono-1,5-lactone and hydrogen peroxide using molecular oxygen as electron acceptor. Its use in the diagnostic assays account for more than 8% of the total yearly budget of the enzymatic kit market worldwide. In present work, strains of Phenerochate chrysosporium NCIM 1106 & 1197, Aspergillus niger NCIM 545 and Penicillium chrysogenum NCIM 709 were screened for maximum production of glucose oxidase. Aspergillus niger NCIM 545 produced maximum glucose oxidase (41.79 U/ml), and hence was selected for further work. One factor at-a-time method was used to investigate the effects of media constituents and fermentation parameters like inoculum size, carbon source, nitrogen source, mineral source, calcium carbonate concentration, temperature and pH on production of glucose oxidase. Maximum glucose oxidase production was obtained at pH 5.5at 30±2°C. Production profile on basal media showed that the time required for maximum glucose oxidase production was 96 hours. Statistical method viz response surface methodology was then used for further optimization of media components. The experiments were designed using the software, Design Expert Version 6.0.10 trial version (State Ease, Minneapolis, MN). Production profile of final optimized media showed the reduction in batch time from 96 hours to 72 hours. Thus the final optimized medium doubled the production of glucose oxidase (93.8 U/ml) as compared to the unoptimized medium.