[Evidence of the existence of hemolysin II from Bacillus cereus: cloning the genetic determinant of hemolysin II].

The hemolysin genetic determinant distinct from cereolysin AB genetic determinant (lecithinase and sphingomyelinase genes) has been cloned in Escherichia coli and Bacillus subtilis cells as an EcoRI fragment (2.9 kb) of Bacillus cereus VKM-B771 chromosome DNA. The hemolytic product encoded by the cloned DNA fragment possessed all the properties of hemolysin II known to date: it was not inhibited by cholesterol, exhibited the Arrhenius effect, and had a relatively long (in comparison with cereolysin) lag period in erythrocyte lysis. The cloned DNA fragment was concluded to contain the gene of hemolysin II from B. cereus. In contrast to previous suggestions that hemolitic activity ascribed to hemolysin II is due to the combined action of sphingomyelinase and lecithinase, the results obtained present convincing evidence that hemolysin II is an independent B. cereus hemolytic factor different from cereolysin AB.