Modification of Ames Test According to Phenotype Features of Prototrophic Escherichia Coli

Background:Iraq is an oil country in addition to an agricultural economie so the using of pesticide has raised very dramatically to cater the food demands of increasing population. Thus, a continuous examination of pesticides is required. Ames test is a standard method for determining the carcinogenic compounds by induce back mutations in auxotrophic strain of Salmonella typhimurium- histidine negative (his -) and biotin-negative (bio -), but in our country-Iraq, this bacterial strain was unavailable in most time. However, this study designed to guess the possibility of employment prototrophic Escherichia coli according to phenotype features instead of S. typhimurium.

Method: A prototrophic Escherichia coli was sensitive to amikacin, erythromycin, chloramphenicol, ciprofloxacin, tobramycin and trimethoprim. The strain was exposed to different concentration of Chlorpyrifos (CPF)as a mutation inducer. The potentiality of mutagenesisof CPF was detected according to phenotype featuresusing antibiotics susceptibility test (AST).

Result:Our result showed that the mutations were induced in some chromosomal genes of E. coli when exposed to CPF in high concentration 80-100%, while con. 10-70% were not. These genes encoded resistance to erythromycin, trimethoprim and tobramycin.

Conclusions:The modified Ames test can consider as a predictive tool for screening a potential carcinogenicity. The potential of genotoxic of the CPF has been detected.