Figure 3

Biofilm formation of WT strain and isogenic mutants of znuACB. A Quantification of biofilm formation of WT C83902 and C83902 ΔznuACB. Surface-adhered biofilm on 96 well microtiter plates was quantified by measuring OD₆₀₀ of ethanol-solubilized CV (2%) after biofilm staining. Data are shown as mean ± standard deviation of triplicate experiments. Significant differences between the mutant and WT C83902 are indicated by p < 0.001 ***. B The decrease of biofilm formation under zinc restriction was characterized by SEM. WT strain and C83902 ΔznuACB were fixed with 2.5% glutaraldehyde after incubation in BIM with or without 30 μM TPEN for 72 h. In order to eliminate the influence of DMSO, the TPEN solvent, BIM with DMSO was set as a control. Fixed bacteria were dehydrated by alcohol gradient, then dried by carbon dioxide critical point dryer and sprayed with gold, finally the sample biofilms were characterized by SEM. The biofilms are marked with a red arrow.