Utilization of L-Glutamic and 2-Oxoglutaric Acid as Sole Sources of Carbon by Escherichia coli

SUMMARY: A wild-type strain of Escherichia coli (W) did not utilize glutamate or oxoglu-tarate as sole source of carbon for growth, but mutants able to grow on each of these compounds were isolated. The abilities to utilize glutamate and oxoglutarate did not necessarily accompany each other. The evidence presented supports the view-that both kinds of mutant involve changes in a permeation mechanism. The mutation to growth on glutamate was always accompanied by appearance of sensitivity to inhibition by 2-methyl-dl-glutamic acid and by partial or even complete loss of glutamic acid decarboxylase. It is proposed that the permeation mechanism for glutamate also allows entry of 2-methylglutamate, a compound which prevents glutamine formation. The loss of glutamate decarboxylase remains unexplained.