Transport and Excretion of L-Lysine in Corynebacterium glutamicum

Summary: L-Lysine transport in Corynebacterium glutamicum was investigated. The bacterium was shown to possess a highly specific, energy-dependent system of active lysine transport. The system transferred lysine into the cells and exchanged intra-and extracellular lysine. Mutations in the transport system did not lead to overproduction ofthe amino acid. Resting cells ofthe parent strain, or of its lysine-producer derivatives with a defective transport system, failed to excrete lysine into the medium. An efflux ofintracellular lysine could be induced by a hyperosmotic shock, and by different membrane-active substances. It has been suggested that C. glutamicum cells are equipped with channels (pores) for excreting lysine from the cytoplasm. These channels appeared to open in response to an increase in the intracellular lysine concentration. The channel permeability also depends on the membrane structure.