Effect of Escherichia coli morphogene bolA on biofilms

Abstract

Biofilm physiology is established under a low growth rate. The morphogene bolA is mostly expressed under stress conditions or in stationary phase, suggesting that bolA could be implicated in biofilm development. In order to verify this hypothesis, we tested the effect of bolA on biofilm formation. Overexpression of bolA induces biofilm development, while bolA deletion decreases biofilms.

FIG. 1.

Positive effect of bolA on biofilm development in microtiter plates. The thickness of biofilms in cultures of different strains was measured by determining optical density (O.D.) at 600 nm after staining them with crystal violet. Error bars represent standard deviations. Biofilm can be visualized by crystal violet staining, as shown on the photos inside the graph.

FIG. 2.

Positive effect of bolA on biofilm development as observed by optical microscopy. Phase-contrast microscopy was used to observe biofilm formation directly on polystyrene plastic. The strains used were E. coli MC1061 (wild type [wt]), SK6582 (ΔbolA), and CMA14 (+bolA).

FIG. 3.

bolA expression and biofilm formation under stress conditions. Under nutrient limitation (0.2% [wt/vol] glucose) and oxidative stress (15 mM of H₂O₂), bolA presence enhances biofilm development. Biofilm thickness for wild-type (MC1061) and ΔbolA (SK6582) strains was measured by crystal violet staining.