Some characteristics of proteolytic enzymes from Pseudomonas fluorescens.

Our interest was stimulated by observing the active proteolytic abilities of a culture of Pseudomonas fluorescens isolated from a frozen chicken pie. The culture liquified gelatin rapidly and attacked casein strongly. In addition, the culture displayed considerable lipolytic and amylolytic activity. The culture was isolated from a tryptone-glucose-meat-extract-agar plate after incubation at 5 C for 7 days. Because many investigators have reported pseudomonads as part of the bacterial flora on foods stored at freezing or refrigeration temperatures, it seemed likely that this culture was a part of the normal psychrophilic bacterial flora. In defrosted foods, the effects of the action of enzymes, presumably from psychrophilic bacteria, are very evident. These enzymatic effects are more extensive than might be expected from the number of bacteria present. The degradative action of proteolytic enzymes is one of the most prominent features of defrost and is marked by the formation of extremely disagreeable odors and flavors which render these products unpalatable. The object of these experiments was: (1) to investigate the effect of some environmental factors on the growth of this culture, (2) to investigate the effect of the environment on the elaboration of the proteolytic enzymes of this culture, and (3) to determine the effect of environmental conditionis on the activity of the proteolytic enzymes.