Purification and characterization of the vascular permeability factor produced by Bacillus cereus

Purification of an extracellular protein exhibiting the vascular permeability activity produced by Bacillus cereus was performed by ammonium sulfate precipitation followed by chromatography on DE-32 cellulose, Sephadex G-100, and Sephadex G-75. The purified protein was found to be electrophoretically and antigenically almost homogeneous although it contained a trace of contaminant. The molecular weight of the protein was calculated to be 45,000 by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The purified protein showed vascular permeability activity and mouse lethal toxicity, and caused fluid accumulation in ligated mouse intestinal loops, whereas it did not show any hemolytic and lecithinase activities. From these findings, the purified protein is suggested to be an enterotoxin (or a diarrheagenic toxin) responsible for diarrhea caused by B. cereus in a diarrheal-type food poisoning.