The influence of the dissolved oxygen concentration on the physiology and ecology of Sphaerotilus natans Kütz.

Using a hermetically closed experimental system the influence of continuously decreasing oxygen concentration on the metabolism of Sphaerotilus natans was investigated by concurrently measuring the temperature, pH, oxygen, sucrose, organic acids, diluted organic carbon (DOC) and dry weight.Oxygen and sucrose were eliminated linearly until the detection limit of <0,1 mg O2/l for dissolved oxygen concentration was reached. Under anaerobic conditions neither sucrose uptake nor organic acid formation occured and autolytic processes were evident. The results confirm that Sphaerotilus natans is an aerobic organism with no capacity for fermentative metabolism.