EFFECT OF DISSOLVED-OXYGEN ON NITROGEN-FIXATION BY A-VINELANDII .1. FREE-CELL CULTURES

As part of an investigation into the use of biological N2 fixation for fertilizer NH3 production, continuous culture studies of respiration and N2 fixation in the aerobic bacteria A. vinelandii under O2 limited conditions were conducted. Respiration and growth rates followed Monod forms with respect to dissolved O2 concentration. Specific O2 fixation rate and nitrogenase activity exhibited maximum values at dissolved O2 concentrations of .apprx. 0.02 mM (10% of air saturation). Apparently, careful control of O2 in the environment is necessary to optimize fixed N production by this organism.