FIG 4.

The ΔlasR mutant has increased rates of nitrate respiration and chlorate consumption and is more sensitive to chlorate. Cell density (OD₅₀₀, filled circles) and nitrate concentrations (open circles) were monitored in the WT and ΔlasR mutant cultures growing under oxic conditions (A), oxic conditions with 40 mM nitrate (B), and anoxic conditions with 40 mM nitrate (C). (D) The WT and ΔlasR cultures were incubated without (squares) or with (filled circles) 1 mM chlorate under anoxic conditions for 72 h, over which time viable-cell counts (solid lines) and chlorate concentrations (dashed lines) were monitored. Data from all experiments show the means of results from three biological replicates, and error bars indicate standard errors.