Aspergillus fumigatus Catalase

Abstract

Catalases are antioxidant enzymes that catalyze the cleavage of hydrogen peroxide into water and molecular oxygen and are widely distributed in nature. There is little information in the literature on the kinetic and biochemical properties of catalases produced by fungi. Therefore, this study aimed to isolate the catalase enzyme from Aspergillus fumigatus, which is known to be a good catalase producer, and to determine its properties. Optimal catalase production was achieved on the seventh day of culturing cells grown at \(37^{\circ}\)C and 155 rpm in a 1-liter YpSs medium containing 1% (w/v) glucose and 0.5 mM H₂O₂. The enzyme was successfully purified 24-fold with a 55% recovery. The molecular weight was determined to be ~70 kDa at SDS-PAGE. The optimal reaction temperature of the enzyme was set at 60°C and pH at 7.0. Km and Vmax values were calculated as 7.4 mM and 1250 \(\mu\)M min^-1, respectively. Stability tests showed that the enzyme could remain active in a wide pH range (4.0-9.0). The thermal stability of catalase was between \(30^{\circ}\)C and \(50^{\circ}\)C. The enzyme was also stable to various solvents such as ethanol, methanol, acetone, and dimethyl sulfoxide depending on the concentration and incubation time. The biochemical properties of the enzyme (low Km, stability towards different pH and organic solvents, etc.) indicate that A. fumigatus catalase can serve as a good biocatalyst for various industrial applications.