Mutagenic effect of azaserine in relation to azaserine resistance in Escherichia coli.

For demonstration of the mutagenic effect of azaserine (mutation from streptomycin dependence to nondependence), higher concentrations of this antibiotic are required with azaserine-resistant Escherichia coli than with the sensitive, parental strain. At barely toxic concentrations of azaserine, however, the mutagenic response of the resistant strain is many times higher than that of the sensitive strain.