GROWTH TEMPERATURE CONTROLS THE PRODUCTION OF A SINGLE EXTRACELLULAR PROTEASE BY PSEUDOMONAS-FLUORESCENS MF0, IN THE PRESENCE OF VARIOUS INDUCERS

The psychrotrophic strain Pseudomonas fluorescens MFO is known to expr ess several enzymatic activities in milk, including extracellular prot eolytic activity, optimally when cells are grown at 17.5 degrees C. In order to study the nature of the mechanisms controlling the productio n of the extracellular protease, we devised a defined medium in which this enzymatic activity was induced by an amino acid and small peptide s. Regardless of the inducer, optimal proteolytic activity appeared at 17.5 degrees C. SDS-PAGE and isoelectrofocussing revealed a single pr otease produced by P. fluorescens MFO with all the inducers used and a t all temperatures examined. The level of proteolytic activity correla ted with the amount of enzyme in the supernatants.