Determination of the Extracellular and Cell-Associated Hydrolase Profiles of Pseudomonas fluorescens Sp. Using the Analytab API ZYM System

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Abstract
The extracellular and cell-associated hydrolase profiles of a number of Pseudomonas fluorescens strains were examined with the Analytab API ZYM system. Esterase/lipase was the only strong extracellular enzyme activity detected (mean 3.33): weak esterase, lipase, and leucine aminopeptidase activities were found with some strains (mean activities of 1.08, 1.53, and 1.40, respectively). Very strong leucine amino-peptidase activity (4.5) was associated with the cells. Cell-associated trypsin, esterase/lipase, acid phosphatase, and phosphoamidase were also found. Neither extracellular nor cell-associated hydrolase profiles changed significantly when cells were grown in skim milk or mineral salts medium at either 5 or 20.degree. C. Similarly, added calcium did not seem required for synthesis of any of the enzymes. The extracellular enzyme profiles differed considerably from those of the cell-associated enzymes for all strains tested. An extracellular proteinase-deficient mutant os strain 32A (RM14) failed to produced significant quantitites of extracellular esterase/lipase activity. Production of cell-associated enzymes was unaffected by the mutation. These results suggest that the Analytab API ZYM system may be useful in identifying psychrotrophs isolated from milk.