<prompt> True about corynebacterium diptheriae isAll types produce toxinToxin production is dependent upon critical concentration of ironHeat stable toxinInhibit cAMP  <response>: Toxin production is also influenced by the concentration of iron in the medium. The optimum level of iron for toxin production is 0.1mg l. The concentration of 0.5 mg l inhibits the formation of the toxin. Only virulent strain produce powerful exotoxin. It inhibits protein synthesis. It is heat liable. Incubation at 37deg C for 4-6 weeks conve toxin to toxoid. Reference: Textbook of Microbiology; Anathanarayan and panickers; 10th edition; Page no: 240 