TABLE 5.

Plasmid transmission frequencies in adherent and nonadherent cells^a

INT-407 cells	Total no. of recombinants recoveredb	Transmission frequencyc
Monolayer on permeable filter support, coinfectedd	338 (1,260)	2 × 10−4 (3 × 10−4)
Nonadherent, coinfectede	4,475 (5,278)	2 × 10−4 (3 × 10−4)
Nonadherent, mixed after independent infectionf	22 (1,406)	2 × 10−6 (3 × 10−4)
Recombinants formed after plating	22 (1,406)	9 × 10−6 (3 × 10−4)

^aThe donor and recipient bacteria were SL1344^R(RP4) and SL1344^N, respectively.

^bThe numbers in parentheses are the numbers of recombinant colonies recovered in the corresponding positive control experiments [INT-407 monolayers infected in series with SL1344^N and SL1344^R(RP4)].

^cIn most cases plasmid transmission frequencies are expressed as the total number of transconjugants per limiting intracellular parent as determined in three representative experiments performed in triplicate; two experiments were performed in triplicate with the coinfected monolayers on permeable filter supports. The transmission frequencies in parentheses are the frequencies from the corresponding positive control experiments.

^dCoinfected cells were infected with both recipient and donor bacteria.

^eNonadherent monolayers were treated with trypsin after the second gentamicin-bathing period.

^fIndependently infected cells were separately infected with either donors or recipients.