THE EXTRACELLULAR PROTEASE FROM PSEUDOMONAS AERUGINOSA EXHIBITING ELASTASE ACTIVITY

Abstract

The extracellular proteases of a highly proteolytic culture of Pseudomonas aeruginosa grown on tryptone–glucose agar were examined in vitro and in vivo. The greater part of the activity was found to consist of a protease exhibiting elastase activity. Through a series of chemical and column (DEAE-Sephadex, pH 8.6) steps, the elastase fraction was isolated and purified 100-fold with an approximate recovery of 68%. Dermonecrosis was obtained in rabbits with the partially purified elastase, but not with a toxic, major protein component free of proteolytic activity which was obtained prior to the elution of the elastase fraction. Purified protease (LD₅₀was equivalent to six protease units) and the non-proteolytic fraction elicited lethality within 24–48 h when singly administered intraperitoneally to mice in concentrations of 50–100 μg protein, whereas crude preparations exhibited little or no lethality below 600–1000 μg protein per mouse. Intraperitoneal administration of eight or more protease units to mice resulted in death within 1–2 h with the concomitant appearance of massive abdominal hemorrhage, intestinal lesions, and numerous pin-point blanched areas on the liver surface; whereas no significant gross pathological changes were noted in mice killed by lethal doses of the non-enzymatic protein fraction.