TABLE 2.

Effect of plasmid on electrotransformation efficiency of B. fragilis calculated from the results of three independent experiments^a

Plasmidb	Selection marker	Size (kb)	Log10 no. of transformants/μg plasmid DNAc
			NCTC9343	YCH46
pLYL05	Cfxr	7.55	4.28 ± 0.13	4.01 ± 0.59
pNLY1	Cmr	7.76	3.34 ± 0.61	1.22 ± 0.53
pVAL-1	Emr	11	0.05 ± 0.09	1.66 ± 0.37
pVAL-2	Cfxr	10.1	1.27 ± 1.10	2.83 ± 0.15

^aB. fragilis cells at mid-exponential growth phase were electroporated with 1.0 μg DNA of each plasmid indicated. After 12 h of postpulse incubation, cells were spread onto GAM agar plates containing the selective antibiotic corresponding to the plasmid used.

^bAll plasmids were purified from E. coli laboratory strain HB101.

^cThe data are means ± standard deviations.