Alternative Amino Acid Requirements in Auxotrophic Mutants of Salmonella Typhimurium

Abstract

Retests on all the auxotrophic mutant strains of S. typhimurium which showed growth originally on more than one amino acid confirmed the list of the number having alternate amino acid requirements not previously found in Escherichia coli or Neurospora. The original 17 such alternatives reported have now been reduced to 6, all of which can be accepted as representing blocks in the pathway of amino acid synthesis. Many of the 17 alternatives previously reported proved to be mixtures of 2 different auxotrophs. A review of the auxotrophs requiring various S compounds showed a correspondence with the series found in E. coli except that 2 groups of mutants, only one of which can use sulfide, are blocked in the use of methionine.