Table 1. Strains used in this study.

Strain	Relevant characteristics	Ottemann strain	Reference or source
E. coli strains
RP437	E. coli K-12 derivative, chemotactic wild-type	KO40	Parkinson (1978)
RP8611	E. coli K-12 derivative Δtsr, Δtar-tap, Δtrg	KO186	J. S. Parkinson* (Surette & Stock, 1996)
H. pylori strains
G27	Wild-type		N. Salama† (Censini et al., 1996)
mG27	Mouse-adapted isolate of G27	KO625	Castillo et al. (2008)
mG27m	Soft agar-selected mG27 isolate	KO1253	This study
mG27m cheY	mG27m ΔcheY : : cat; CmR	KO1257	This study (cheY allele in Terry et al., 2005)
mG27m tlpD	mG27m ΔtlpD : : cat; CmR	KO1259	This study (tlpD allele in Williams et al., 2007)
SS1	Wild-type	KO441	J. O’Rourke‡ (Lee et al., 1997)
SS1 cheA	SS1 ΔcheA : : cat; CmR	KO855	Terry et al. (2005)
SS1 tlpA	SS1 ΔtlpA : : cat; CmR	KO661	Andermann et al. (2002)
SS1 tlpC	SS1 ΔtlpC : : cat; CmR	KO565	Andermann et al. (2002)
SS1 tlpD	SS1 ΔtlpD : : cat; CmR	KO914	Williams et al. (2007)
J99	Wild-type	KO479	N. Salama† (Alm et al., 1999)
CYP3401	Wild-type	KO637	D. Berg§ (Mizote et al., 1997)
M6	Wild-type	KO613	E. Joyce|| (Eaton et al., 2002)
ATCC43504	Wild-type	KO669	ATCC. Also known as NCTC 11637 (Joyce et al., 2000)

^*The University of Utah.

^†Fred Hutchinson Cancer Research Center.

^‡University of New South Wales.

^§Washington University, St. Louis and University of California, San Diego.

^||Tufts University School of Medicine.