GROWTH AND NITROGEN-FIXING ACTIVITY OF THE BATCH CULTURE OF XANTHOBACTER-AUTOTROPHICUS AT VARIOUS CONCENTRATIONS OF DISSOLVED-OXYGEN

Effect of various partial pressures of dissolved oxygen (pO(2)) on the growth, uptake of carbon and nitrogen sources, respiration, and nitro genase activity was studied in a homogeneous batch culture of diazotro phic bacterium Xanthobacter autotrophicus DSM-432. The partial pressur e of oxygen was maintained at a specified, fixed level throughout the entire cultivation process. The maximum nitrogenase activity at any pO (2) was observed on the 3rd day of cultivation, when amine nitrogen (b ut not the carbon source) in the culture medium was exhausted. Nitroge nase activity and the affinity of the culture for oxygen were reciproc ally related.