True about corynebacterium diphtheria includes all of the following except:
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." Elek's gel precipitation test is in vitro test for toxin detection.
Deep invasion is not seen
Elek's test is done for toxigenicity
Metachromatic granules are seen
Toxigenicity is mediated by chromosomal change