Purification and properties of mutanase from Bacillus circulans

Abstract

Bacterial strain HU-M1 was isolated as a mutan-degrading microbe from soil and identified as Bacillus circulans. From an HU-M1 culture supernatant mutanase was purified 260-fold by ammonium sulfate fractionation and DEAE-Toyopearl 650M (twice), Toyopearl HW55-F, and Butyl-Toyopearl 650M column chromatography with an activity recovery of 10%. The M r of the mutanae is 160,000 (monomer). The optimal pH and temperature for the mutanase are pH 6.9 and 50°C for a 10-min reaction. The mutanase is stable at up to 40°C for 60-min and at pH 6.0 to 11.0 at 4°C for 48 h, and logarithmically inactivated at 54°C with a half life of 2.6 min. Mutant hydrolysates produced by the enzyme had di-, tri-, and tetramer of glucose and the final hydrolysis was 38%.