Biotchnol. Tech., Vol.10. NO.12., 937-940, 1996

Use of Methicillin and Ampicillin Mixture as a Selective Pressure in the Cultivation of Recombinant E. coli

Dong-Cheol Lee and Hak-Sung Kim

Ampicillin was rapidly degraded by an extracellular -lactamase and was therfore ineffective to isolate plasmid-harboring cells in the cultivation of recombinant E. coli for the production of thermostable D-hydantoinase. An effective way of preventing the degradation of ampicillin, methicillin was employed as a -lactamase inhibitor. A mixture of methicillin and ampicillin was observed to effectively function as a selective pressure, and consequently plasmid stability and enzyme productivity of recombinant E. coli were highly maintained.