You do a transposon mutagenesis experiment on bacterium X. You are interested in mutants that have decreased ability to produce a toxin. In several cases, you find that toxin production has...

You do a transposon mutagenesis experiment on bacterium X. You are interested in mutants that have decreased ability to produce a toxin. In several cases, you find that toxin production has disappeared. In one case, however, the toxin is produced, but at a lower level than by the wild-type strain. Also, whereas toxin production in the wild-type strain was triggered by the exposure of the bacteria to low-iron conditions, the mutant makes as much toxin in highiron medium as in low-iron medium. How could you explain these two types of mutants? Why might the second type of mutation (constitutive expression of the toxin gene) reduce the ability of the bacterium to cause disease?