A pseudomonas cepacia population was isolated which had reduced suscep
tibility to iodine and maintained resistance when subcultured several
times in phosphate buffer. This population was also resistant to iodin
e after growth in a minimal medium containing glycerol but not glucose
. Addition of cAMP to glucose-grown cells caused increased resistance
to iodine. Iodine-resistant cultures also demonstrated reduced suscept
ibility to chlorination but not to heat or metals (Cu/Ag). The results
indicate that halogen resistance can be expressed in varying degrees,
dependent on the carbon source, and cAMP may promote this expression.
Thus, a catabolite repression-like mechanism may cause resistant cult
ures grown in some media to become more sensitive to halogens.