OVER-PRODUCTION OF THERMUS PROTEASE IN DENSE CULTURE OF ESCHERICHIA-COLI USING 2 CARBON-SOURCES

Escherichia coli JM109(DE3) harboring expression plasmid pkAQN Delta C 30, which carries the Thermus protease aqualysin I (AQI) gene, was cul tivated with glucose as a sole carbon source. The final cell concentra tion was over 15 g dry weight/l and the amount of AQI produced reached approximately 130 kU/ml broth. Moreover, by using two carbon sources, glucose and glycerol, the production yield was increased to over 200 kU AQl/ml, while suppressing the formation of inhibitory acetic acid.