Strains used in this work.

aJC13509 has the following genotype: sulB103 lacMS286 φ 80dIIlacBK1 argE3 hi-4 thi-1 xyl-5 mtl-1 rpsL31 tsx. The lacMS286φ80dIIlacBK1 code for two partial non-overlapping deletions of the lac operon [73], [74].
bSelect for KanR and then screen for other marker phenotypically or by PCR.
cSelect for TetR and then screen for other marker phenotypically or by PCR.
dSelect for CatR and then screen for other marker phenotypically or by PCR.
eSelect for AmpR.
fSelect for AlaS+.
gThis deletion allele was created by first transducing the kan resistant derivative from the Kieo collection into the strain as indicated in the reference column. pLH29, carrying the flp gene, was then introduced and Kan sensitive derivatives were screened ([75].
hrecX::cat was amplified with prSJS748,749 using pACYC184 (New England Biolabs) as a template. recX::cat was transferred to the chromosome using the exo-bet method [76] next to the recA allele indicated. This original combination of mutants were named and saved as the strain indicated as the donor in this cross.
iThese recAo or recA mutations were first constructed on a plasmid as described in the Materials and Methods. They were then transferred to the chromosome using the method of Datsenko and Wanner [76] using a strain that was lexA3 malE::Tn10 in a JC13509 background with pKD46 encoding exo and bet. This original combination of mutants were named and saved as the strain indicated as the donor in this cross.
jFull notation for ygaD mutation is ygaD1::kan .Full notation for recX mutation is del(recX)4166::cat. Full notation for recBCD mutation is del(recBCD)::cat. Full notation for Ωgfp mutation is Δattλ::sulApΩgfp-mut2.