Background and Aim:Cold active enzymes have high catalytic efficiency at low temperature because this enzyme increased flexibility of the active sites.These enzymes are used in the leather industry, waste water analysis, detergents, food etc. Methods:The aim of this study was to optimize cold-active protease from Stenotrophomonas sp. by one factor at a time (OFAT) method. The best initial pH was determined by adjusting the pH of production medium at 6, 7, 9, and 11. The impact of different carbon sources (glucose, lactose, sucrose, and starch) was investigated by adding 1% (w/v) of each one to the production medium. To examine the effect of inoculation level on protease production, 0.5%, 1.5%, 2.5%, and 3.5% (v/v) of bacterial suspension containing about 1.5×108 cell/ml was used. Results:The highest level of protease production occurred after 48 hours (0.312 Uml-1). The highest level of protease was produced at pH 9 (0.601 Uml-1), while further increase in medium pH decreased enzyme production. Adding starch to the production culture increased protease production (0.643 Uml-1). Conclusion: Cold-adapted proteases thus can be use to optimize present day industrial processes and for developing future technologies with less energy inputs and process cost by removing the cost of heat inactivation step.

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