THE EFFECT OF VIRUS INFECTION ON THE UTILIZATION OF TRYPTOPHAN BY ESCHERICHIA COLI

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Abstract
-E. coli B/l. a tryptophan-requiring mutant of E. coli B, has been used in the microbiological assay of low concns. of L-tryptophan. A method has been devised for measuring the depletion of tryptophan from a medium incubated with normal and virus-infected bacteria. E. coli B grown in a medium containing acid-hydrolyzed casein and glucose develops little or no tryptophanase but is capable of the immediate utilization of tryptophan under conditions suitable for growth. E. coli B infected with phage, suspended in a defined medium containing 20 amino acids, rapidly removed L-tryptophan from the medium. The uptake of tryptophan was a function of the virus strain used, the rates of depletion by virus-infected cells being in the order T2>T4>T6.