Table 1.

High fidelity of F-plasmid partition in E. coli

	Loss ratea		Copy numberb
Generation timec T (min)	pJYB249	pDAG115	At cell division (n)	Per cell (cn)	Average foci number per celld (fn)	Clusterization ratioe
45	<0.001	0.058 ± 0.1	5.16	3.57	3.13	0.12
242	0.001	0.128 ± 0.002	4.06	2.81	2.18	0.22

The level of plasmid F clusterization is low in fast and slow E. coli growing conditions. The clusterization level is estimated by the difference between the average number of foci and the average number of plasmids per cell.

^aThe loss rate of the plasmids used in the microscopy assay (pJYB249) and in the determination of the plasmid copy number (pDAG115) were obtained from at least three independent measurements, except for pJYB249 grown in the presence of CSA performed in duplicate. pDAG115 is a partition defective mini-F plasmid (41) that allows for estimating the copy number at cell division (see Materials and methods).

^bThe plasmid copy number per cell is ln2 times the copy number at cell division n (19).

^cThe generation time (T) was estimated from measurements of culture optical densities at 600 nm.

^dThe number of foci per cell was determined by epifluorescence microscopy.

^eThe clusterization ratio is determined by the following formula: (cn − fn)/cn.