Purification and some properties of the hemolytic toxin aerolysin

Abstract

Aerolysin, the hemolytic toxin produced by Aeromonas hydrophila, was purified by a combination of salt fractionation, gel filtration and ion-exchange and hydroxyapatite chromatography. The resulting protein has a MW of 51,500 and appears homogeneous by polyacrylamide gel electrophoresis in sodium dodecyl sulfate. It is free of detectable protease and phospholipase activities. The purified protein can be separated into 2 active components with pI [isoelectric point] of 5.39 and 5.46 by isoelectric focusing. Both components are found in the original culture supernatant indicating that the multiplicity is not due to proteolysis during isolation. Purified aerolysin is unstable even at 25.degree. C and its hemolytic action is inhibited by certain reducing agents including ferrous iron and cysteine. It appears to be the only toxin hemolytic to human cells that is produced by A. hydrophila under the conditions described.