<prompt> On blood agar target appearance of Cl. perfringens is due to which toxin ?Alpha toxinTheta toxinBeta toxinMu toxin  <response>: Ans. is a i.e., Alpha toxin Two impoant characteristic feature of Cl. perfringens are :?Target hemolysis double zone hemolysis on blood agar. It is a narrow zone of complete hemolysis by theta toxin which is surrounded by a wider incomplete hemolysis by alpha-toxin.Naeglers reaction detects alpha toxin phospholipase or lecithinase C. When Cl. perfringens is grown on a medium with the antitoxin spread on one half of the plate, colonies on the other half without the antitoxin will be surrounded by a zone of opacity. There will be no opacity around the colonies on the half of the plate with the antitoxin, due to the specific neutralisation of the alpha-toxin. 