Gesellschaft zur Förderung von Medizin-,
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Microbial sensors are used in the workgroup “Microbiology/Biosensor Technology” in automatical Flow analysis systems (e.g. for specific measurement of different analytes in aqueous or gaseous phases). The measured variable is the oxygen demand of aerobic, heterotrophic microorganisms or the oxygen release from phototrophic cells such as microalgae or cyanobacteriae.

The membrane immobilized receptor microorganisms are placed in front of an oxygene electrode in a respiration measuring cell and are supplied continously with oxygen by aflowing carrier medium. In this carrier, the sample is intermittently injected and transported to the immobilized cells. If the sample contains substrates, then an oxygen consumption is happend. A high oxygen demand produces a high measuring signal and is correlated with a high substrate concentration.

For phenolic compounds living cells of the strain Rhodococcus spec. PI are used. The Rhodococcus immobilisates are very stable and can be stored at 4°C for several years. The measuring system enables determination of phenol in aqueous phase in the range of 0,5 mg/l up to several g/l. Different measuring ranges up to 3 decades of the phenol concentration can be adjusted by dynamic variation of the injected sample amount.

Another application is the measurement of biodegradable substances by use of a gasdiffusion module in combination with the described flow through biosensor system (e.g. determination of hydrogene sulfide with immobilized Thiobacillus cells).