Purification and Some Properties of a Novel Amylase from an AlkaliTolerant Strain of Acremonium

Abstract

A fungus producing a novel neutral amylase, namely, the alkalitolerant strain TOF225, was isolated from samples collected in a residential dwelling in Tokyo, and it was identified as a species of Acremonium from its morphological characteristics. The fungus produced an extracellular amylase in the presence of starch and sodium carbonate or sodium bicarbonate. The maximal rate of production of the enzyme was obtained when the fungus was cultured aerobically at 28°C for 4 days in an alkaline medium. The enzyme was purified by chromatog raphy on DEAEToyopearl, Sephadex G50, MonoQ and Superdex 75. The purified enzyme was electrophoretically homogeneous and its molecular weight was 53, 000 daltons. The optimum pH and temperature for activity were 6.57.5 and 45°C, respectively. The enzyme was stable up to 30°C between pH 6.0 and 10.5 for 10 min, and it was thermostable in the presence of 1 mM CaCl2 at temperatures up to 35°C. The isoelectric point of the enzyme was 5.94. This amylase is considered to be an alkalitolerant enzyme.