the accuracy of BOD determination [1]. At the same time, BOD
biosensors based on microbial co-cultures can be insufficiently stable
due to a gradual change of their composition [4]. BOD biosensors
based on a complex microbial population, as, for instance, in activated
sludge, have the best capability of detecting a broad range
of substrates; still, due to the instability of the consortium, in the
course of time these biosensors yield the least reproducible results.
Several solutions of this problem have been proposed. Thus, the
biosensor can be periodically calibrated or else thermally killed
activated sludge can be used [5]. Still, inconvenience of operation
and technical complexity of these approaches restrict applicability.