ISOLATION OF MUTANTS AFFECTING TRYPTOPHANASE PRODUCTION IN ESCHERICHIA COLI.

Gartner, Theodore K. (University of California, Davis), and Monica Riley. Isolation of mutants affecting tryptophanase production in Escherichia coli. J. Bacteriol. 89:313-318. 1965.-Mutants of Escherichia coli K-12 were isolated which appear to have suffered an alteration in the regulation system governing tryptophanase synthesis. A novel selection method was used to isolate tryptophanase mutants from tryptophan synthetase deletion mutants. Mutants were obtained which exhibited the following phenotypes either singly or in combination with others: constitutivity and inducibility at 13 C (wild type is not inducible at 13 C), constitutivity and hyperinducibility at 37 C. Mutation to constitutivity at 13 C seems to require two mutational changes of the wild type. Other mutants, presumably structural gene mutations, were isolated which lack tryptophanase activity under all conditions tested.