Studies on the Amylolytic Enzyme Associated with the Black Mould Deterioration of Eko, a Nigerian Fermented Food

Abstract

Aims: To characterize amylase enzymes responsible for the spoilage of Eko,  a Nigerian fermented food and to provide the best way to preserve it. Study Design: The experiment was carried out to extract the enzyme involved in the deterioration of Eko, it was partially purified using ion-exchange chromatography. Place and Duration of Study: Department of Microbiology, Obafemi Awolowo University, Ile Ife, between 1994 and 1996. Methodology: Eko was obtained from the new market Ile Ife and cut into slices, the slices were inoculated with spores of Aspergillus niger, on the eleventh day after inoculation, the enzyme was extracted, partially purified using ion-exchange chromatograpghy and characterized. Results: Within eleven days of inoculation, the Eko slices were extensively covered by the fungal spores, the amylase secreted by the Aspergillus niger was harvested and characterized. Its molecular weight was 70,000 Da, the optimum pH and temperature were 6 and 35 0C respectively, enzyme activity increased with increase in starch concentration with optimum activity at 0.9 mg/ml, the apparent Km for starch hydrolysis was 0.4 mg/ml. Cations such as Na+ and K+ stimulated amylase activity but was inhibited by EDTA and HgCl2 Conclusion: The result of this work showed that amylase enzyme was produced by Aspergillus niger in the infected Eko slices also that the enzyme contributed to the degradation process, therefore, keeping Eko in conditions that will hinder the secretion of amylase enzyme or hinder its activity and the subsequent growth of A. niger will prolong the shelf life of Eko.