Plasmid Stability in High Cell Density Cultures of E. coli HB101(pBR322)
大肠杆菌E.coli HB101(pBR322)高密度培养过程质粒的稳定性

Plasmid stability and the activity of (-lactamase were examined in the factorial fed-batch cultures of E.coli HB101(pBR322) in a fermentor. No loss of plasmid pBR322 was observed when temperature shifted from 33 oC to 39 oC, pH from 6.4 to 7.2, dissolved oxygen (DO) from 40% to 80%, the feed rate from 5.4 g/h to 10.8 g/h under the condition of density up to 27.3 g/L and the specific growth rate up to 0.73 h(1. The specific activity of (-lactamase, however, decreased in high cell density cultures.