대장균내 발현벡터의 안정성 향상으로 L-페닐알라닌 생산

Plasmid Stability and L-Phenylalanine Production in Escherichia Coli

The stability and L-phenylalanine productivity of a low-copy-number plasmid pSY200-14, in Escherichia coli AT2471, were investigated in batch culture. The pSY200-14 plasmid was stable in batch culture between 30℃ and 40℃ and L-phenylalanine productivity was shown similar to or higher than that of the high-copy-number plasmid pSY130-14. It was shown that the plasmid stability and L-phenylalanine production were regulated by temperature. Maximum yield of L-phenylalanine, 147㎎/ℓ was obtained using low-copy-number plasmid pSY200-14 in AT2471 at 38.5℃. The host strain AT2471 with pSY130-14, produced 100㎎/ℓ of L-phenylalanine at the same temperature. In this study, the L-phenylalanine synthesis enzyme genes, aro FFR and phe AFR, controlled by a temperature sensitive repressor, cI857. were cloned into the low-copy-number plasmid pSY200-14. In conclusion, plasmid stability and optimum L-phenylalanine production were constantly achieved in batch culture at high temperature.