The effect of chemicals on induction of recombination in an F' histidine merozygote of Escherichia coli



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Several chemical mutagens and chemotherapeutic agents were shown to stimulate the formation of recombinants in several partial diploid strains of Escherichia coli K[lowered 12]. The compounds were also tested for their effect on the viability of the bacteria. MNNG was found to increase recombination between fourteen and twenty-five fold depending on the concentration of MNNG used. The compound DES increased recombination by fifteen fold and DKS increased recombination by thirteen fold. The alkylating agent EMS increased the frequency of recombination by twenty-two fold. Nitrous acid increased recombination between six and twenty fold depending on the length of treatment. Ultraviolet irradiation was shown to increase the frequency of recombination between four and six fold over the control depending on the length of exposure to ultraviolet irradiation. The base analogs 2 aminopurine and 5 bromodeoxyuridine increased recombination between two and three fold depending on the amount used. The chemotherapeutic agent 5-iodo-2'-deoxyuridihe showed a 2.5% frequency in recombination, while ths control was 0%. The drug arabinosyl cytosine also showed a 2.5% frequency in recoinbinaticn, while the control was 0%. The folic acid inhibitors, aminopterin, amethopterin and dichloroamethopterin increased recombination between four to six fold. The antitumor agent 6 methylthiopurine showed a three fold increase in recombination The drug cytoxan showed an eight fold increase in recombination. It was also demonstrated that KKNG could induce the formation of an F' episome to carry the histidine region.