Triornithine resistant strains of Escherichia coli. Isolation, definition, and genetic studies

Triornithine resistant (TOR) mutants were isolated from several strains of E. coli K12. All of the mutants were found to be oligopeptide transport deficient (Opp^-). The dipeptide transport system (or systems) was not altered. The rate of growth of these mutants, the morphology of the cells and their colonies and the sensitivity to the phages T₁, T₄, P1, and phi80 were similar to the parental strains, indicating no dramatic changes at the cell envelope. All Opp^- mutants tested showed 98% linkage to trp in sexual recombination, and 80 to 95% P1 mediated cotransduction frequencies. The opp gene is therefore the closest marker to the trp operon. A mutant with a deletion in the region att phi80, tonB, trp still contained the opp gene (or genes), indicating its appearance on the cysB side of the trp operon.