It was reported that the E.coli mutant strain exhibited the resistance against amitrole (AT) which had used as a pesticide and inhibits the bacterial growth. In order to elucidate the mechanism on the AT-resistance in E.coli, we prepared the E.coli mutant strain by treating with chemical mutagen, MNNG, and then selected the AT-resistant E. coli strain. The obtained mutant strain was possible for proliferating even in the M9 minimal medium containing 2 mg/ml AT. Therefore, we examined the expressed proteins in the mutant strain, which was cultured under various conditions. As a result, it was suggested the expression of 22 kDa protein (P1) was suppressed as the AT concentration was increased in M9 medium. By the amino acid sequence analysis, it was proved that P1 must be alkyl hydroperoxide reductase C22 protein (ahpC). On the other hand, the expression of P2 protein in mutant strain has increased in the M9 medium containing 2mg/ml AT, and partial amino acid sequence of P2 was consistent with zinT (yodA) protein. From these results, it is likely that the amitrole-resistance in E.coli might be regulated by soxRS regulon, not oxy R, like adaptation for the oxidative stress
