True about corynebacterium diphtheria is all except

Toxigenicity of the diphtheria bacilli depends on the presence in it of corynephages which acts as the genetic determinant controlling toxin production. The diphtheria toxin acts by inhibiting protein synthesis. Specifically, a fragment B heparin binding and fragment A inhibits polypeptide chain elongation in the presence of nicotinamide adenine dinucleotide by inactivating the elongation factor EF-2. Reference: Textbook of Microbiology; Anathanarayan and panicker's; 10th edition; Page no: 240