An analysis of the instability kinetics of plasmid pHSG415 during continuous culture of Escherichia coli.
The effect of dilution rate on the instability kinetics of Escherichia coli RV308(pHSG415) during glucose-limited continuous culture is examined. Two nonlinear models are fitted to the data, both of which characterize the plasmid-host system in terms of the rate parameters R (for the plasmid segregation rate) and d mu (for the specific growth rate difference between plasmid-free and plasmid-bearing single cells). In the first model, both R and d mu have constant values with respect to time. In the second, either R or d mu is represented as a time-dependent function. Although both models fit the data equally well, it is demonstrated that the constant rate parameter model gives results which appear to be misleading. A comparison is also made among some of the many plasmid instability models (both mass-balance and segregated) which have appeared in the literature. It is found that all of these give identical trajectories and differ only in the definitions of the rate parameters used.
Dunn
A
A
School of Pure and Applied Biology, University of Wales College, Cardiff, UK.
Davidson
A M
AM
Day
M J
MJ
Randerson
P F
PF
D002455:Cell Division; D004926:Escherichia coli / Q000235:genetics* / Q000254:growth & development*; D007700:Kinetics; D008962:Models, Theoretical; D010957:Plasmids; D011815:R Factors; D013997:Time Factors