[Determination of the biochemical oxygen demand in nutrient media using microbial flow-through electrodes]

Biochemical oxygen demand (BOD) in some culture media was determined by means of flow-through microbial electrodes, based on Hansenula anomala, Escherichia coli K-12, and activated sludge obtained from the All-Union Scientific-Research Institute of Applied Enzymology (Vilnius). The sensitivity of the electrodes was 112.1, 65.5 and 32.8% O2, respectively, in the presence of 1 mM glucose as substrate. A maximum sensitivity of the electrodes, based on E. coli and activated sludge, was observed on pyruvate oxidation--120 and 82.3% O2 in the presence of 1 mM pyruvate. The yeast electrode exhibited a minimum sensitivity for sucrose--9.3% O2/mM. The time of the electrode response varies from 8 to 35 min, depending on the substrate used. BOD depends on pH of the solution. The microbial electrodes retained the initial sensitivity for 33--38 days. The were used for estimation of BOD in the Rider's and Shopfer's media.