SUMMARY When grown in nutrient broth, Pseudomonas fluorescens produced a heat‐labile proteolytic enzyme system that was active against blended fresh egg white, spray‐dried egg white, and hemoglobin. The proteolytie enzyme system was released into the growth medium when the viable cell population had reached a maximum. The proteolytic activity was greater at the higher (25°C) than at the lower temperatures (15, 5°C) of culture incubation. Some purification was obtained by fractionation with ammonium sulfate and cellulose‐column chromatography. The addition of Fe++ to the enzyme preparation greatly increased its activity.

SUMMARY The growth characteristics and proteolytic activities of 3 strains of Pseudomonas fluorescens were determined in blended fresh egg white (initial pH 7.8–8.0), egg white adjusted to pH 7.4, egg white with added yolk, 30‐day‐old egg white (pH 9.0), and various egg media at the 2% protein level. In all cases the number of viable cells increased markedly during the first l–2 weeks of incubation. Under certain conditions of incubation, strains 5 and 17 showed proteolytic activity in blended fresh egg white, and strain 10 in egg white adjusted to pH 7.4 and in egg white with added egg yolk. Growth and proteolytic activity were also observed in the 30‐day‐old egg white (pH 9.0). All strains showed growth and proteolytic activity in the spray‐dried egg white growth medium (pH 7.4, autoclaved). Proteolysis was also determined on solid media with various egg constituents as substrate.