Table 1. Strains used in this study.

strain	relevant properties	reference
Salmonella strains:
NCTC12023	WT	lab collection (NCTC, Colindale, UK)
HH107	ΔsseF::aphT	[35]
HH108	ΔsseG::aphT	[35]
MvP373	ΔsscB sseF sseG	[10]
P2D6	ssaV::mTn5	[36]
E. coli strains:
DH5α	general cloning strain	Invitrogen
XL10 Gold	general cloning strain	Stratagene
Phages:
P22 HT	highly efficient transduction	[37]