Partial characterization of aerolysin, a lytic exotoxin from Aeromonas hydrophila

Conditions are defined for the production, in high titers, of an extracellular hemolytic toxin of Aeromonas hydrophila, here termed "aerolysin." Substantial purification of the toxin was accomplished by means of salt fractionation, dialysis, and gel filtration, with a yield of 24% of the starting activity. Analysis of the product by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate revealed a single, heavy protein band and a number of faint protein bands. The estimated molecular weight of the heavy band (50,000) was in close agreement with that (53,000) of the substance responsible for hemolytic activity as determined by gel filtration. Purified aerolysin is a labile substance, apparently protein. It is not inactivated by any of several proteases under the conditions employed nor is it inhibited by any of several lipids tested. About 0.1 mug administered to mice intravenously is lethal. The physical properties of aerolysin show considerable resemblance to those described for the exotoxin of Pseudomonas aeruginosa.