Observations on the Production of Tryptophanase by Esch. Coli; in Particular the Effect of the Presence of Glucose and Amino- Acids on the Formation of Tryptophanase

FILDES [1938], referring to the claims of Happold & Hoyle [1936] that 'the failure to produce indole by cultures of E. coli grown in the presence of glucose is due to the non-production of a tryptophanase system', suggests that this is but a partial truth and that the tryptophanase system in the cells consists oftwo parts, a ' constitutive' part and an 'adaptive' part, ofwhich only the 'adaptive' part is not produced in the presence of glucose. Fildes further states that suspensions of E. coli are always capable of catalysing the oxidation of tryptophan to indole even when grown in the absence of tryptophan or in the presence of glucose and tryptophan. The main points of difference in technique and findings between the two series of investigations are: Fildes obtained his cells from cultures grown on a synthetic medium containinig glucose and tryptophan and reported that indole was formed in these cultures and that the suspensions derived therefrom when incubated with tryptophan produced indole. Happold & Hoyle, having sought to explain the absence of indole formation which occurs in glucose bouillon 'cultures, grew their cells in this medium; indole was not produced in such cultures nor was there enzyme formation, since when non-viable preparations from these cells were placed in contact with tryptophan, indole was not formed, though similar preparations from bouillon cultures were active. The latter technique does not allow neo-enzyme formation to occur during the course of the experiment. I