title: Bioluminescent Escherichia coli strains for the quantitative detection of phosphate and ammonia in coastal and suburban watersheds.
abstract: Accumulation of phosphate and ammonia in estuarine systems and subsequent dinoflagellate and algal blooms has been implicated in fish kills and in health risks for fishermen. Analytic chemistry kits are used to measure phosphate and ammonia levels in water samples, but their sensitivity is limited due to specificity for inorganic forms of these moieties. An Escherichia coli bioluminescent reporter system measured the bioavailability of inorganic nutrients through fusion of E. coli promoters (phoA or glnAp2) to the luxCDABE operon of Vibrio fischeri carried either on the chromosome or on a multicopy plasmid vector, resulting in emission of light in response to phosphate or ammonia starvation. Responses were shown to be under the control of expected physiological regulators, phoB and glnFG, respectively. Standard curves were used to determine the phosphate and ammonia levels in water samples from diverse watersheds located in the northeastern United States. Bioluminescence produced in response to nutrient starvation correlated with concentrations of phosphate (1-24 ppm) and ammonia (0.1-1.6 ppm). While the ammonia biosensor measured nutrient concentrations in tested water samples that were comparable to the amounts reported by a commercial kit, the phosphate biosensor reported higher levels of phosphate in Chesapeake water samples than did the kit.
authors.affiliation: Department of Biology, Swarthmore College , Swarthmore, Pennsylvania, USA.
authors.forename: Cristina V
authors.initials: CV
authors.lastname: Cardemil
authors.forename: Dana R
authors.initials: DR
authors.lastname: Smulski
authors.forename: Robert A
authors.initials: RA
authors.lastname: Larossa
authors.forename: Amy Cheng
authors.initials: AC
authors.lastname: Vollmer
mesh_terms: D048908:Aliivibrio fischeri / Q000235:genetics; D000641:Ammonia / Q000032:analysis* / Q000494:pharmacology; D019677:Artificial Gene Fusion; D015374:Biosensing Techniques / Q000379:methods*; D002138:Calibration; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000737:chemistry* / Q000187:drug effects / Q000235:genetics; D008163:Luminescent Measurements; D009584:Nitrogen / Q000494:pharmacology; D009876:Operon / Q000235:genetics; D010710:Phosphates / Q000032:analysis* / Q000494:pharmacology; D011401:Promoter Regions, Genetic / Q000235:genetics; D015533:Transcriptional Activation / Q000187:drug effects; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000494:pharmacology
chemical_list: D010710:Phosphates; D014874:Water Pollutants, Chemical; D014867:Water; D000641:Ammonia; D009584:Nitrogen