<prompt> What genetic pecularity is there in pathogenic toxigenic strain of corynebacterium diphtheriae but not in nonpathogenic strain -Presence of R-factorPresence of geneIntegrated temperate phagePresence of MDR gene  <response>: Ans. is c i.e., Integrated temperate phage The toxigenicity of the diphtheria bacilli depends on the presence in it of corynephages tox . Nontoxigenic strains may be rendered toxigenic by infecting them with beta phage or some other larger phage.This is known as lysogenic conversion or phage conversion. 