title: Bioavailable nitrate detection in water by an immobilized luminescent cyanobacterial reporter strain.
abstract: 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.
authors.affiliation: Institute of Technical Biochemistry, University of Stuttgart, Allmandring 31, 70569 Stuttgart, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Mbeunkui
authors.forename: C
authors.initials: C
authors.lastname: Richaud
authors.forename: A-L
authors.initials: AL
authors.lastname: Etienne
authors.forename: R D
authors.initials: RD
authors.lastname: Schmid
authors.forename: T T
authors.initials: TT
authors.lastname: Bachmann
mesh_terms: D001682:Biological Availability; D015374:Biosensing Techniques / Q000379:methods*; D000458:Cyanobacteria / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D008163:Luminescent Measurements; D009566:Nitrates / Q000032:analysis*; D014867:Water / Q000032:analysis*
chemical_list: D009566:Nitrates; D014867:Water