Bioavailable nitrate detection in water by an immobilized luminescent cyanobacterial reporter strain

F Mbeunkui, C Richaud, A-L Etienne, R D Schmid, T T Bachmann, Till Bachmann

Research output: Contribution to journalArticlepeer-review


Cyanobacteria are a major group of photosynthetic bacteria that can accumulate in surface water as so-called "blooms" in response to environmental factors such as temperature, light and certain nutrients such as N, P, and Fe. Some species of cyanobacteria produce toxins, causing a considerable danger for human and livestock health. As a consequence, monitoring of bloom formation and toxin production of drinking water supplies has become a major concern. To enable prediction and monitoring of cyanobacterial blooms, tools to detect nutrient bioavailability in water would be advantageous. A whole-cell biosensor was developed for monitoring nitrate (NO(3-)) bioavailability in aquatic ecosystems using the recombinant bioluminescent cyanobacterial strain Synechocystis PCC 6803 harboring an insertion of a luxAB-kmr fusion with nblA1 in its chromosomal DNA, leading to PnblA::luxAB-kmr. This reporter strain was designated N1LuxKm. Cells were immobilized in microtiter plates and showed a dose-dependent response to nitrate deprivation. The resultant CyanoSensor could detect nitrate in the 4-100 micro M concentration range after a sample incubation time of 10 h under continuous illumination (50 micro E m(-2) s(-1)). The optimal temperature for sensor operation was 29 degrees C and the immobilized biosensor could be stored at 4 degrees C in dark for about 1 month without significant loss of sensitivity.
Original languageEnglish
Pages (from-to)306-12
Number of pages7
JournalApplied Microbiology and Biotechnology
Issue number3
Publication statusPublished - 2002


  • Biological Availability
  • Biosensing Techniques
  • Cyanobacteria
  • Luminescent Measurements
  • Nitrates
  • Water


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