Table 1.

Bacterial strains and plasmids used in this study.

Strain or plasmid	Relevant characteristicsa	Reference or source
E. coli
SY327	Δ(lac pro) argE(Am) rif malA recA56 λ pir lysogen	[19]
S17-1	thi pro hsdR hsdM+ recA RP4-2-Tc::Mu-Km::Tn7 λ pir lysogen	[20]
V. alginolyticus
ZJ-O	Opaque variant of wild strain, isolated from diseased cultured fish in Guangdong province on the Southern China coast. Apr	[17]
ZJ-T	Translucent variant of wild strain; isolated from diseased cultured fish in Guangdong province on the Southern China coast. Apr	[17]
ΔrpoX-O	ZJ-O carrying an in-frame deletion of rpoX. Apr	This study
ΔrpoX-T	ZJ-T carrying an in-frame deletion of rpoX. Apr	This study
CrpoX-O	ΔrpoX-O complemented in trans with wild-type rpoX gene. Apr and Cmr	This study
CrpoX-T	ΔrpoX-T complemented in trans with wild-type rpoX gene. Apr and Cmr	This study
Plasmids
pDM4	Cmr, suicide vector with an R6K origin(pir requiring) and sacBR of Bacillus subtilis	[21]
pDMrpoX	Cmr, pDM4 containing a mutant allele of rpoX	This study
pDMCrpoX	Cmr, pDM4 containing the wild-type allele of rpoX	This study

^aCm^r, chloramphenicol resistant

Ap^r, ampicillin resistant.