Growth curves of the <i>R. sphaeroides</i> wild type (black) and the 2.4.1Δ<i>irr</i> mutant (gray) under normal iron (continuous line) and under iron limitation (dashed line) conditions are shown.

<p>The optical density at 660 nm (OD₆₆₀) of microaerobically grown <i>R. sphaeroides</i> cultures was determined over time. The data represent the mean of at least three independent experiments and error bars indicate standard error of the mean.