Optimization of submerged steady-state fermentation process for glucose oxidase production by Aspergillus niger isolated from local environment

Abstract

Glucose oxidase (GOX) is an enzyme with large scale applications in various industries as a biosensor for the detection of the glucose level of body fluids. The present study aims to optimize the cost-effective steady-state fermentation process for the maximum production of glucose oxidase by Aspergillus niger isolated from a locally contaminated onion. For low-cost enzyme production, the possibility of a submerged steady-state fermentation process was evaluated. The enzyme production was assessed by using local low-cost saccharose (C12H22O11) as carbon source and sodium nitrate (NaNO3) as the nitrogen source. Effect of peptone and urea on GOX production by A. nigerwere also examined. The initial pH for the optimal production of GOX was found 5.5. The addition of K+in fermentation medium increases enzyme activity while Mg2+was found to inhibit glucose oxidase production by A. niger. Although Ferric ion (Fe3+) showed the highest GOX productivity,it forms reddish-brown colour which hinder colour measurement in GOX activity. Incubation time and culture morphology were also examined to increase glucose oxidase production.

Keywords

• glucose oxidase
• aspergillus niger
• steady-state fermentation
• czapek dox medium.