Fig. 4

Ammonium production in AZBB163 grown on Burk's medium versus B/MoFeS medium. Shown are the ammonium production (top) and OD₆₀₀ (bottom) results from growing AZBB163 in both standard Burk’s (B) medium and B/MoFeS medium (supplemented with nitrogenase cofactor-related elements containing twofold increase in iron (Fe), fivefold increase in molybdenum (Mo), and threefold increase in sulfur (S) versus B medium). Cultures were grown at 26 °C and shaken at 180 rpm, and were grown as 60 mL cultures in 125 mL Erlenmeyer flasks. Bottom graph optical density plotted on a log₂-based scale (y-axis). Data points indicate averages, while error bars represent standard deviation (N = 5)