<b>Bacterial strains and plasmids used in this study.</b>

a<p>In genotype descriptions, the subscripted number refers to a composite deletion and insertion of the indicated gene. P, promoter; TT, T4 ip III transcription terminator; <i>ori</i>, origin of replication; Kan^R, kanamycin resistance; Str/Spc^R, streptomycin/spectinomycin resistance; Amp^R, ampicillin resistance.