The effect of a LYSE exporter overexpression on L-arginine production in Corynebacterium crenatum.

Corynebacterium crenatum SYPA is an aerobic and industrial L-arginine producer. A lysE deletion mutant was constructed searching a natural function of this in C. crenatum SYPA. Tracking determination of intracellular and extracellular L-arginine in the minimum culture CGXII showed that LysE did play an important role in transporting L-arginine from intracellular to extracellular, without which the accumulation of intracellular L-arginine of C. crenatum SYPA could reach an extremely high concentration. Nevertheless, the lower intracellular concentration of L-arginine could decrease the feedback inhibition in the biosynthesis of L-arginine. To improve the yield from excretion, we attempted to achieve overexpress in the L-arginine transporter in C. crenatum SYPA. Thus, the heterologous and homologous expressions of EcargO and CclysE, respectively, were carried out by means of the shuttle plasmid pJCtac in C. crenatum SYPA. It was found that L-arginine production was improved by 13.6 % because of the overexpression of lysE in the strain (SYPA/pJCE) contrast to the wild-type strain and reached 35.9 g/L, whereas L-arginine production of the strain SYPA/pJCO was scarcely changed. Consequently, we succeeded in obtaining a mutant form of LysE which has an effect to decrease the intracellular concentration of L-arginine in an L-arginine producer of C. crenatum SYPA and found that the production of L-arginine by C. crenatum carrying lysE was improved. These results show the importance of the factor (lysE) involved in the excretion of L-arginine on its over-production in C. crenatum.