CIRCLEGROW®

CIRCLEGROW is a premixed bacterial growth medium for growing large quantities of plasmid DNA in host cells. The super rich formulation allows rapid growth of E. coli to high density, averaging 3 times the density of cells grown in L-broth. Cells in stationary phase in CIRCLEGROW keep growing slowly and maintain a high copy number of plasmids. In conventional media, cells stop growing in stationary phase, some cell death occurs and plasmid copy number decreases.

The growth curve shows an example of the saturation density of E. coli grown in L-broth versus CIRCLEGROW. When cells reach stationary phase in L-broth and stop growing, some cell death and lysis occurs, with a resulting decrease in plasmid DNA yield. In contrast, cells grown in CIRCLEGROW enter stationary phase and their rate of growth slows but does not stop completely for several days. Plasmid copy number in dense, slow growing CIRCLEGROW cultures does not decrease and cell death and lysis does not occur, resulting in an increased yield of plasmid DNA per unit culture volume.