Table 1. Bacterial strains and plasmids.

Strain or plasmid	Relevant characteristics	Source or reference
strains
E. coli DH5α	General laboratory strain	Gibco-BR
E. coli S17-1	General laboratory strain	Simon et al. 1983
E. coli EDL933	wild type	ATCC 43895
E. coli EDL933	rifampicin tagged, Rifr	This study
E. coli EDL933	stx1(del), , Km, Kmr	This study
E. coli EDL933	stx2(del), , Cm, Cmr	This study
E. coli EDL933	stx1–2(del), , KmCm, KmrCmr	This study
E. coli EDL933	eae(del), , Km, Kmr	This study
plasmids
pWM91	Suicide vector, Apr	Metcalf et al., 1996
pKD3	plasmid carrying Cm resistance cassette, Cmr	Datsenko and Wanner, 2000
pKD4	plasmid carrying Km resistance cassette, Kmr	Datsenko and Wanner, 2000

Rif^r, rifampicin resistance; Km^r, kanamycin resistance; Cm^r, chloramphenicol; Ap^r, ampicillin resistance.