Denitrification in Lake Kinneret in the presence of oxygen*

Abstract

SUMMARY. Denitrification experiments under anaerobic and aerated conditions were carried out in the laboratory with Lake Kinneret water and with pure cultures of the denitrifying bacteria Pseudomonas aeruginosa 2 Kin isolated from the lake. Although losses of nitrogen in Lake Kinneret due to denitrification have been found to occur during periods when dissolved oxygen exceeded 5 mg l−1 it was found that under aerated conditions glucose as a carbon source must be added in order to get denitrification in the laboratory.Disappearance of nitrogen during the experiments was due to denitrification as shown by the nitrogen balance calculated for each sampling. The ATP content showed that no proliferation of cells took place during the experiment.The rate of denitrification was strongly influenced by and was directly proportional to nitrate concentrations. Temperature has a very slight effect on the denitrification rate. Q10 for the range 15–30°C was 1.35.The role of denitrification in the nitrogen balance of Lake Kinneret is discussed.