Table 2

Summary of the diverse conditions used and final protocol

Stepa
Condition
Obtention of recombinant colonies (CFU/ml)b
Final established condition

Construction of the amplimer
Short homologous arms
No
Long primers

Long homologous arms
Yes
Single PCR reaction for tet

Single PCR reaction
21 for Tc
Three PCR reaction for cat

Three PCR reactions
19 for Cm





Amount of amplified DNA to be transformed
0.1 μg
0
0.5 μg

0.25 μg
0


0.5 μg
21 Tc, 19 Cm





Culture volume used for preparation of electrocompetent cells
5 ml (2 × 109 CFU/ml)
0
50 ml (5.1010 CFU/ml)

10 ml (1010 CFU/ml)
0


25 ml (2.5 × 1010 CFU/ml)
1 Tc, 0 Cm


50 ml (5 × 1010 CFU/ml)
9 Tc, 8 Cm





Temperature after electroporation
30°C
2 Tc, 1 Cm
37°C

37°C
15 Tc, 9 Cm





Arabinose concentration media
1 mM
18 Tc, 9 Cm
0.1 M

10 mM
10 Tc, 8 Cm


0.1 M
20 Tc, 11 Cm





Concentration of antibiotic in plating media
Tc 20 μg/ml, Cm 20 μg/ml
1 Tc, 0 Cm
Tc 5 μg/ml, Cm 5 μg/ml

Tc 5 μg/ml, Cm 5 μg/ml
21 Tc, 19 Cm


a Each set of experiments was performed independently of the other tests with one phage for each antibiotic.

b Phage used for tet was ØVTB55; Phage used for cat was ØA9.

Serra-Moreno et al. BMC Molecular Biology 2006 7:31   doi:10.1186/1471-2199-7-31