EFFECT OF CULTIVATION CONDITIONS ON ACTIVITY OF Α-Amylase FROM a TROPICAL STRAIN ASPERGILLUS FLAVUS LINK

Abstract

An important integral part of the physiology of the fungal cell is the nature of the cascade of extracellular enzymes produced by fungi. A tropical strain Aspergillus flavus Link obtained from deteriorated tomato (Solanum lycopersicum) fruits grew in a growth nutrient medium composed of MgSO4.7H20, K2HPO4, KH2PO4, FeSO4.7H2O, potassium nitrate and starch at 30oC. Extracellular proteins produced by the isolate in the medium expressed α-amylase activity. The enzyme was partially purified by ammonium sulphate precipitation followed by dialysis. The enzyme exhibited optimum activity at 35oC and at pH 6.0. It possessed an apparent Km of 7.1 mg/ml for the hydrolysis of starch. The enzyme was stimulated by Na+ and Ca2+ but inhibited by ethylenediamine tetraacetic acid and 2,4-dinitrophenol. It lost 64.1% of its activity within 20 min of heating at 80oC. Of the nitrogenous compounds potassium nitrate, ammonium sulphate and casein, casein as nitrogen source in the defined growth medium with starch as carbon source supported most activity of α-amylase by the fungal isolate. Observations during the partial purification and characterization of the enzyme are herein reported.

α-amylase production obtained from Aspergillus niger ATCC 1004 by solid state fermentation using Croton linearifolius residues as substrate

“…On the effect of pH and temperature on the activity of the α-amylase enzyme produced by Aspergillus niger FAB-211, using a culture medium containing maltose and yeast extract Asrat and Girma (2018) identified a maximum activity at pH 6 and a temperature of 45º C. This same pH value for better enzyme activity was also found when α-amylase was produced by other fungi of the Aspergillus genus. When checking the effect of pH on the α-amylase activity produced by Aspergillus oryzae, using residual water with starch, Shah et al (2014) found a maximum activity for the enzyme at pH 6 and a temperature of 50º C. While Adejuwon, Tsygankova and Alonge (2018) found a maximum activity of α-amylase produced by Aspergillus Flavus Link, with a nutritive culture medium composed of MgSO4.7H20, K2HPO4, KH2PO4, FeSO4.7H2O, potassium nitrate and starch at pH 6 and temperature 35º C. Therefore, there is a variation in the optimum pH and the optimum activity temperature of the α-amylase produced.…”

Optimal Inventory Strategies for Pharmaceutical Products Incorporating Carbon Emissions

“…α-Amylase activity was assayed using the modified method of Pfueller & Elliott [20] and Adejuwon et al [22]. The reaction mixture was 2 mL of buffered (0.02m citrate phosphate buffer pH 6.0), soluble starch (Sigma) and 0.5 mL enzyme.…”