Purification and Characterization of an Extracellular Protease Produced by Pseudomonas fluorescens M3/6

Abstract

Pseudomonas fluorescens strain M3/6 was inoculated into reconstituted NDM and incubated at 7°C for 46 d. A significant amount of extracellular protease was produced, mainly during the latter part of the culture's life cycle. The protease was purified using ammonium sulfate fractionation, ion-exchange chromatography, and gel filtration. The isolated protease had activity on azocasein, α-, β-, and κ-caseins and a plasmin substrate but did not have plasminogen activator activity. The protease had a molecular weight of 45 kDa, an isoelectric point of pH 8.25, a broad temperature and pH range for activity, and was less heat stable in the isolated form than in the cell-free extract. © 1991, American Dairy Science Association. All rights reserved.