GLUTAMATE EXCRETION IN ESCHERICHIA-COLI - DEPENDENCY ON THE RELA AND SPOT GENOTYPE

Glutamate excretion due to amino acid starvation was investigated in ''stringent'' and ''relaxed'' strains of Escherichia coli. The observed excretion process is relA-dependent, carrier-mediated, and glutamate-specific. After induction, excretion was detected within less than 2 min and continued for more than 5 h with a rate of 7-10 nmol (mg dry weight)(-1) mim(-1). Using carbonyl cyanide m-chlorophenylhydrazone or polymyxin B nonapeptide, together with valinomycin, it was shown that glutamate excretion is driven by the membrane potential.