FED-BATCH CULTIVATION OF RECOMBINANT ESCHERICHIA-COLI JM103 AND PRODUCTION OF THE FUSION PROTEIN SPA=ECORI IN A 60-L WORKING VOLUME AIRLIFTTOWER LOOP REACTOR

SPA=EcoRI fusion protein was produced by Escherichia coli JM103 carryi ng the multicopy expression plasmid pMTC48, the multicopy repressor pl asmid pRK248, and the multicopy protection plasmid pEcoR4 in a 60-L wo rking volume airlift tower loop reactor on M9 minimal medium with gluc ose. Cell mass concentration, total cell count, number of colony-formi ng units, specific growth rate, yield coefficient, and metabolite (ace tate, pyruvate, succinate, lactate, ethanol) concentrations were monit ored during the growth phase and gene expression. Gene expression was induced by temperature shift or chemically by isopropyl-thiogalactosid ase in the airlift tower loop reactor (ALTR) at constant cultivation t ime and in a small stirred tank reactor at different cultivation times . During induction, the cultivation medium was supplemented with conce ntrated Luria-Bertani (LB) medium. The intracellular enzyme activity w as evaluated as a function of the time after the start of the inductio n. It was found that the reduction of the glucose concentration and in crease of the dissolved oxygen concentration reduced the acetate produ ced and increased the intracellular enzyme activity.