The purpose of this study is to improve the thermo-stabilty of alkaline protease produced by Bacillus sp. using rice bran during solid state fermentation. After partial purification of alkaline protease, various parameters namely effect of temperature and metal ions on enzyme activity was investigated. The suitable temperature for alkaline protease activity was observed at 50°C. Among various metal ions examined, calcium ion improved the thermal stability of the protease considerably. At 50 °C, addition of 1 mM calcium chloride in enzyme solution resulted in 26% increase in enzyme activity. Influence of calcium ions on half life of alkaline protease were compared at temperatures above optimum.
