The effect of virus infection on the utilization of tryptophan by Escherichia coli.

Several techniques have been utilized in this laboratory for the study of the nutritional requirements for virus synthesis in Escherichia coli infected by bacteriophage. For instance, it was observed that when E. coli strain B grown in nutrient broth was resuspended in a simple medium (F) and infected with T2r+ bacteriophage, there was a marked decrease in the amount of virus produced, as well as an increase in the latent period before virus liberation. These effects were overcome when the F medium was supplemented with amino acids, purines, and pyrimidines (Fowler and Cohen, 1948). When L-histidine, L-isOleucine, L-glutamic acid, L-leucine, L-phenylalanine, L-valine, or L-tryptophan was omitted singly from the complex medium, the burst size of the infected cells was decreased (Cohen and Fowler, 1948). When L-tryptophan was added to unsupplemented F, a stimulation of virus production did not result (Fowler and Cohen, 1948). As a result of other types of analysis and the reversal of the inhibition caused by 5-methyltryptophan by tryptophan, this amino acid has been shown to be a specific requirement in virus synthesis in the E. coli-T2 system (Cohen and Fowler, 1947). Tryptophan also acts as an adsorption cofactor in the T4 and T6 strains of phage studied in this laboratory (Anderson, 1945). A study of this amino acid, therefore, presented an interesting starting point in a closer examination of the requirements for individual amino acids of bacteriophage-E. coli systems as revealed by their depletion from a medium during the infection process. Preliminary observations concerning the utilization of various amino acids in a synthetic medium in which E. coli B was infected with T2r+ phage have been conducted in this laboratory through the use of single dimensional paper chromatography (Cohen, 1949b). The usefulness of this technique to determine the fate of amino acid constituents of a defined medium, before and after growth of bacteria, had been suggested by Linggood and Woiwod (1948, 1949). However, our results using this technique were inadequate in that reliable quantitative data could not be easily obtained, and the method of microbiological assay of amino acids appeared more readily applicable.