The Effect of Carbon Source of Growth on α-Amylase Production by Aspergillus flavus

Adekunle Odunayo Adejuwon, Patrick Ojo Olutiola


Background: Aspergillus flavus is known for its capability of production of aflatoxins in food grains in the tropics. It was also recently demonstrated as capable of production of α-amylase in a defined medium with potassium nitrate and some other nitrogen compounds as nitrogen source for fungal growth and development (Adejuwon et al., 2015, Advances in Bioscience and Bioengineering).  Materials and methods: In this current investigation a same defined growth medium with potassium nitrate as nitrogen source was inoculated with spore suspensions of approximately 7x105 spores per ml of Aspergillus flavus. The carbon source for growth was varied and was independently bread, starch, maltose, sucrose, lactose, glucose and galactose. Incubation was at 30oC. Extracellular proteins produced in medium was monitored daily and analysed for α-amylase activity. Results: The proteins produced by Aspergillus flavus in the inoculated medium exhibited α-amylase activity. All the carbon compounds used in the investigation supported α-amylase expression in the fungus however, starch and maltose were the most supportive with optimum activity expressed as 417 and 364 units/mg protein respectively on the 5th day of incubation. Slight delayed expressions were with bread, starch, maltose, lactose, glucose and galactose.  Conclusion: All the carbon compounds used in this investigation will support industrial production of α-amylase by Aspergillus flavus with starch and maltose being most supportive when potassium nitrate is used as a source of nitrogen for growth and development at 30oC. However, Aspergillus flavus poses a danger as a potential biomarker in bioterrorism.

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