Maintenance of some ColE1-type plasmids in chemostat culture

Mol Gen Genet. 1980;180(3):579-84. doi: 10.1007/BF00268063.


When cells carrying the plasmids RP1, pDS4101 (a ColK derivative) or pDS1109 (a ColE1 derivative) were maintained in chemostat culture in the absence of antibiotic selection, plasmid-free segregants were not detected after 120 generations of nutrient-limited growth. By contrast, plasmid-free segregants of pMB9- and pBR322-containing cells arose after approximately 30 generations, irrespective of the host genetic background. However, even though pDS1109 was maintained its copy-number fell five-fold during 80 generations of limited growth. It is suggested that loss of pBR322 occurs following a similar copy-number decrease which results in defective segregation of the plasmid to daughter host cells. This defective segregation was not complemented in trans by either RP1 or pDS4101.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Cell Division
  • Culture Media / pharmacology
  • Escherichia coli / cytology
  • Escherichia coli / genetics*
  • Escherichia coli / ultrastructure
  • Genetic Complementation Test
  • Plasmids*
  • Time Factors


  • Culture Media