Thanks Anders for your explanation.
With reversion I mean: If I grow the CB+ mutants not in a selective
medium (with CB) but in a rich medium for several days they can not
degrade CB anymore. I have not still search for the reasons why it
happens, but it is most probably an insertion than an inversion. If I
could demostrate that in the presence of CB, the number of cells where
the mutation ocurs is higher than in cells cultivated in rich medium,
could I say that there is a DNA regulation? Have you heard something
By the way CB is not lethal for the strain, but the wild type can not
grow because it can not degrade it and use it as C- and energie source.