Figure 3

Length of lag phase (h; bars), and final biomass (OD _600; circles) of B. azotoformans MEV2011 as function of the initial oxygen concentration in the culture. Cultures were grown in TSB (10 g L⁻¹, Scharlau®) amended with 3 mM KNO_3. Black and grey bars and circles represent data from replicate incubations. Growth was first detected when oxygen had been consumed to <30–35 μM (see Figure 2), explaining the increasing lag time with increasing oxygen concentrations. The final OD was almost identical in all incubations and unrelated to the initial oxygen concentration, indicating that oxygen did not contribute to biomass production.