Optimization of Amylase Production in Three Fungal Species

Abstract

Aim: Amylase is an important enzyme that is employed in starch processing industries, used in the hydrolysis of polysaccharides such as starch into simple sugar constituents. In this study, we investigated the abilities of several isolated amylolytic soil fungi to produce amylase. Materials and Methods: Soil samples collected from the botanical garden, Department of Plant Science and Biotechnology, University of Jos was serially diluted and screened for the presence of amylase producing fungi. Optimization studies was performed across different parameters; Incubation period (7 days), different temperatures (25-60°C), different pH (5-9), different starch concentration (0.2-2%), carbon source (sucrose, maltose, lactose). Results: A total of 15 isolates belonging to 7 genera were isolated. Soil samples were analyzed for their ecological parameters. The plate assay showed that three species T. viride (62mm), P. citrinum (50.25mm), and A. niger (67mm) had the largest zones of clearance and highest amylolytic activity thus were selected for further studies. For submerged fermentation, optimum amylolytic activity was observed at 24 hours of incubation for all three species T. viride (7.92 IU/ml), P. citrinum (5.04 IU/ml), and A. niger (7.00 IU/ml). Maximum enzyme activity was observed at incubation temperature of 45°C (17.10 IU/ml) for T. viride, 50°C (33.60 IU/ml) for P. citrinum, and 50°C (14.30 IU/ml) for A. niger. The maximum enzyme activity was at pH 9 (20.40 IU/ml) for T. viride, pH 11 (18.50 IU/ml) for P. citrinum, and pH 7 (25.80 IU/ml) for A. niger. T. viride and P. citrinum recorded an optimum enzyme activity of 15.40 IU/ml and 13.20 IU/ml respectively when sucrose was used as a carbon source while A. niger recorded an optimum activity of 7.28 IU/ml when maltose was used. Starch concentration of 2% showed the highest enzyme activity of 16.52 IU/ml, 15.4 IU/ml and 14.00 IU/ml, for T. viride, A. niger and P. citrinum, respectively. Conclusion: Trichoderma viride, Penicillium citrinum, and Aspergillus niger showed potential of producing amylase which is useful in the biodegradation of biological wastes.