ABSTRACT
This chapter describes the principles, the construction, and the measurement of microbial biosensors. The industrial applications of biochemical and microbiological processes in such fields as the production of pharmaceuticals, food manufacturing, wastewater treatment, and energy production are increasing. Microbial biosensors can be constructed by placing immobilized microorganisms in close proximity to a thermistor that measures the metabolic heat they produce. A commercially available conventional dissolved oxygen electrode is the most general and suitable transducer for a microbial biosensor. Entrapment in a gel matrix is a favored method of immobilization, particularly for microbes that have small substrates, which diffuse into the matrix more readily than large substrates. Biosensors offer the possibility of real-time analysis, which is particularly important for the rapid measurement of analytes in industry, for example in process monitoring and control, in which there is a demand for the in situ determination of flow rates, and levels of contaminants.
