Contribution of znuK and znuL genes for growth in zinc deprivation. (A) Growth of NA1000, zur, znuK and znuL mutant strains under different regimens of zinc availability. Aliquots of 20 μL from a 10−5 dilution of cultures were plated on M2 medium without or with addition of 500 μM EDTA (3 days growth), 850 μM EDTA (5 days growth) or 850 μM EDTA and 1.7 mM ZnCl2 (3 days growth). (B) Growth of NA1000, CC0815::mini-Tn5, znuK::mini-Tn5 and znuL::mini-Tn5 strains harboring plasmid pMR20 containing or not the genes indicated. Aliquots of 20 μL from a 10−5 dilution of cultures were plated on M2 medium containing tetracycline (1 μg ml−1) and the same additions as in (A).