Transport of basic amino acids and regulation of aspartate kinase activity in thialysine and L-canavanine resistant strains of Serratia marcescens.

Growth of Serratia marcescens was not inhibited by high concentrations of L-lysine and its structural analogues, L-cancavanine and S-(2-aminoethyl)-L-cysteine (thialysine). This insensitivity was not caused by deficient transport of basic amino acids, unlike in mutant strains of Escherichia coli having the same properties. The tested strains showed a lack of regulation at the aspartate kinase level toward L-lysine and thialysine. The data indicate great intraspecific variability for aspartate kinase regulation in S. marcescens.