Monitoring structure and activity of nitrifying bacterial biofilm in an automatic biodetector of water toxicity.

Automatic biodetector of water toxicity is a biosensor based on monitoring of catalytic activity of the nitrifying bacteria. To create a standardized biosensing system, development of the biofilm must be characterized to determine the prerequisites for its biological (biocatalytic) stability. In this paper, growth of biofilm comprising ammonium-oxidizing bacteria (AOB) and nitrite-oxidizing bacteria (NOB) in the open cellular polyurethane material polyurethane sponge bioreactor has been investigated. Dynamics of the biofilm formation was estimated using AOB and NOB metabolic activity and the volume occupied by these two types of bacteria in the biofilm. Spectrophotometry liquid ion chromatography and image cytometry were used, respectively, for these measurements. A mathematical model of the dynamics of biofilm formation was established. These data indicate that open cellular polyurethane material is a good basis for the immobilization of nitrifying bacteria. Moreover, growth of the biofilm leads to its stable structural form, whose biocatalytic activity (12.29 for AOB and 6.84 micromol min(-1) for NOB) is constant in the long term.