SDS-PAGE showing OMP profiles of P. aeruginosa grown in MH (lanes 2 and 5), eluates from SLUCs (lanes 3 and 6), and zinc-supplemented MH (final zinc concentration, 36.8 μg/ml) (lanes 4 and 7). Lanes: 1, molecular weight markers; 2 to 4, OMP profile of PAO1; 5 to 7, OMP profile of OprD-negative PAO1. White arrow, OprD2; black arrow, OprD3. Numbers on the left are in kilodaltons.