<prompt> True about corynebacterium diphtheria 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>: Ans. d Toxigenicity is mediated by chromosomal change Corynebacteriophage beta carries the structural gene tox encoding diphtheria toxin and a family of closely related corynebacteriophage are responsible for toxigenic conversion of tox- C.diphtheria to tox phenotype. Eleks gel precipitation test is in vitro test for toxin detection. 