<prompt> True about corynebacterium diptheria includes all of the following except :Deep invasion is not seenEleks test is done for toxigenicityMetachromatic granules are seenToxigenicity is mediated by chromosomal change  <response>: Corynebacteriophage beta carries the structural gene tox encoding diptheria toxin and a family of closely related corynebacteriophage are responsible for toxigenic conversion of tox C.diptheria to tox phenotype.Eleks gel precipitation test is in vitro test for toxin detection. 