Production and Characterization of Glucoamylase by Aspergillus niger

Background and Objective: Glucoamylase is a potent starch degrading enzyme whose cheap production has been an area of research. Its production by Aspergillus niger in solid-state fermentation was studied using dried garden pea peel as a substrate, which enormously reduced the production cost. The current study intended to produce glucoamylase by a cost-effective strategy and exhaustively characterize the enzyme. Material and Methods: Garden pea peel was used as a substrate in solid state fermentation by Aspergillus niger for the production of glucoamylase under process parameters. Response surface methodology, a statistical tool for optimization, was applied to setup the experimental design for glucoamylase production. Characterization studies of the enzyme were carried out with temperature, pH, metal salts and elemental composition analysis. Results and Conclusion: The process parameters were temperature, amount of substrate and time of fermentation. Glucoamylase production was highest in the pH range of 5.4- 6.2, was stable at pH 3.8, and maintained its maximum activity even at 70oC for 30 min. It showed higher catalytic efficiency when incubated with metal ions Fe^2+, Cu^2+, Mg^2+, and Pb^2+. Km and Vmax for glucoamylase were 0.387 mg of soluble starch ml^-1 and 35.03 U μl^-1 min^-1, respectively. Glycogen was also used as a substrate, which gave an increased Km by 2.585, whose KI was found to be 0.631. Energy-dispersive X-ray spectroscopy was performed for obtaining composition of the pea peel. C, N, and O were found to be 12.53%, 29.9%, and 55.27% by atomic weights, respectively. Cost- and time-effective production of glucoamylase was achieved by utilizing dried garden pea peel (a vegetable residue) powder as the substrate for production. Its high stability ensures efficient utilization under industrial conditions. This work provides a very good platform for the enzyme immobilization studies and scale up production in future. Conflict of interest: The authors declare that there is no conflict of interest.