Growth temperature controls the production of a single extracellular protease by Pseudomonas fluorescens MF0, in the presence of various inducers.

The psychotrophic strain Pseudomonas fluorescens MFO is known to express several enzymatic activities in milk, including extracellular proteolytic activity, optimally when cells are grown at 17.5 degrees C. In order to study the nature of the mechanisms controlling the production of the extracellular protease, we devised a defined medium in which this enzymatic activity was induced by an amino acid and small peptides. Regardless of the inducer, optimal proteolytic activity appeared at 17.5 degrees C. SDS-PAGE and isoelectrofocussing revealed a single protease produced by P. fluorescens MFO with all the inducers used and at all temperatures examined. The level of proteolytic activity correlated with the amount of enzyme in the supernatants.