Fig. 1. Impact of sugar metabolites on E. coli antibiotic sensitivity. (a) MG1655 WT was treated with 30 μg carbenicillin ml^− 1, 3 μg gentamicin ml^− 1 or 0.125 μg ciprofloxacin ml^− 1 alone (black bars) or in combination with 12 mM l-arabinose (white bars), 10 mM d-glucose (grey bars) or 10 mM d-mannitol (dotted bars). Survival was monitored after 18 h of treatment. (b) OD₅₉₅ of MG1655 cultures during 18 h of treatment without (open triangles) or with 30 μg carbenicillin ml^− 1 alone (vertical lines) or in combination with sugars (arabinose, open circles; glucose, closed triangles; mannitol, open diamonds). (c) Survival of MG1655 mutants deficient in arabinose metabolism (ΔaraC) and glucose metabolism (Δglc) after 18 h of no treatment (black bars), carbenicillin treatment alone (chequered bars) or in combination with sugars (arabinose, white bars; glucose, grey bars; mannitol, dotted bars). Concentrations as in (a). All c.f.u. ml^− 1 values are shown as mean ± sd (n>3). *p < 0.05, **p < 0.01.