Table 4.

Transfer frequency and stability of pSUP202 and pSUP404.2

	pSUP202	pSUP404.2
Transfer frequencya	4.8 × 10−5	3.5 × 10−3
	4.8 × 10−6	3.4 × 10−1
		4.9 × 10−4
Stabilityb
After 1st inoculation	+	+
After 2nd inoculation	−	+
After 10th inoculation	−	+

^aTransfer frequency determined in independent experiments: number of Cm^R Sm^R B. bacteriovorus HD100-S1 transconjugants per E. coli S-17.1 donor; number of transconjugants were determined on double layer plates containing streptomycin and chloramphenicol with prey E. coli K-12 JC3272 [pBR329]

^bStability determined in liquid cultures. + growth in liquid cultures containing streptomycin and antibiotic selective for the corresponding plasmid. − No growth because of loss of plasmid mediated antibiotic resistance