Tryptophan Metabolism and its relation to Phage Resistance in Escherichia coli

SUMMARY: A series of phage-susceptible tryptophan-requiring mutants of Escheri-chia coli, strain B, were found to fall into five distinct phenotypes as determined by their alternate growth response to anthranilic acid and indole, and by the substances which they accumulated in the culture fluids. An unidentified substance partially characterized by colorimetric reactions and absorption spectrum accumulated in the culture fluid of two of these types. Tryptophan-requiring T1 phage resistant mutants (23/1, IT) which were readily obtained by phage selection could not be isolated by the penicillin method. This mutant represents a unique tryptophanless phenotype, not only in terms of its resistance to Tl phage, but also on the basis of: (1) accumu-lation of a new metabolic product; (2) growth stimulation by histidine and tyrosine; (3) suppression of accumulation of certain metabolic products by the other tryptophan auxotrophs; (4) epistatic expression of phenotype when superimposed on the trypto-phan auxotrophs by secondary mutation. In analysing mutants of Escherichia coli, strain B, which are resistant to the T series of coli phages a consistent and reproducible association is foun