title: Paper-based chromatic toxicity bioassay by analysis of bacterial ferricyanide reduction.
abstract: Water quality assessment requires a continuous and strict analysis of samples to guarantee compliance with established standards. Nowadays, the increasing number of pollutants and their synergistic effects lead to the development general toxicity bioassays capable to analyse water pollution as a whole. Current general toxicity methods, e.g. Microtox(®), rely on long operation protocols, the use of complex and expensive instrumentation and sample pre-treatment, which should be transported to the laboratory for analysis. These requirements delay sample analysis and hence, the response to avoid an environmental catastrophe. In an attempt to solve it, a fast (15 min) and low-cost toxicity bioassay based on the chromatic changes associated to bacterial ferricyanide reduction is here presented. E. coli cells (used as model bacteria) were stably trapped on low-cost paper matrices (cellulose-based paper discs, PDs) and remained viable for long times (1 month at -20 °C). Apart from bacterial carrier, paper matrices also acted as a fluidic element, allowing fluid management without the need of external pumps. Bioassay evaluation was performed using copper as model toxic agent. Chromatic changes associated to bacterial ferricyanide reduction were determined by three different transduction methods, i.e. (i) optical reflectometry (as reference method), (ii) image analysis and (iii) visual inspection. In all cases, bioassay results (in terms of half maximal effective concentrations, EC50) were in agreement with already reported data, confirming the good performance of the bioassay. The validation of the bioassay was performed by analysis of real samples from natural sources, which were analysed and compared with a reference method (i.e. Microtox). Obtained results showed agreement for about 70% of toxic samples and 80% of non-toxic samples, which may validate the use of this simple and quick protocol in the determination of general toxicity. The minimum instrumentation requirements and the simplicity of the bioassay open the possibility of in-situ water toxicity assessment with a fast and low-cost protocol.
authors.affiliation: Department of Genetics and Microbiology, Universitat Autònoma de Barcelona (UAB), Bellatera, Barcelona, Spain. Electronic address: fpujol.vila@gmail.com.
authors.forename: F
authors.initials: F
authors.lastname: Pujol-Vila
authors.affiliation: Department of Genetics and Microbiology, Universitat Autònoma de Barcelona (UAB), Bellatera, Barcelona, Spain.
authors.forename: N
authors.initials: N
authors.lastname: Vigués
authors.affiliation: Department of Genetics and Microbiology, Universitat Autònoma de Barcelona (UAB), Bellatera, Barcelona, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Guerrero-Navarro
authors.affiliation: Department of Genetics and Microbiology, Universitat Autònoma de Barcelona (UAB), Bellatera, Barcelona, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Jiménez
authors.affiliation: Department of Genetics and Microbiology, Universitat Autònoma de Barcelona (UAB), Bellatera, Barcelona, Spain.
authors.forename: D
authors.initials: D
authors.lastname: Gómez
authors.affiliation: Department of Genetics and Microbiology, Universitat Autònoma de Barcelona (UAB), Bellatera, Barcelona, Spain.
authors.forename: M
authors.initials: M
authors.lastname: Fernández
authors.affiliation: CRIT (Center for Research and Innovation in Toxicology) Technical University of Catalonia (UPC), Terrassa, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Bori
authors.affiliation: CRIT (Center for Research and Innovation in Toxicology) Technical University of Catalonia (UPC), Terrassa, Spain.
authors.forename: B
authors.initials: B
authors.lastname: Vallès
authors.affiliation: CRIT (Center for Research and Innovation in Toxicology) Technical University of Catalonia (UPC), Terrassa, Spain.
authors.forename: M C
authors.initials: MC
authors.lastname: Riva
authors.affiliation: Centre Nacional de Microelectrònica (IMB-CNM, CSIC), Bellatera, Barcelona, Spain.
authors.forename: X
authors.initials: X
authors.lastname: Muñoz-Berbel
authors.affiliation: Department of Genetics and Microbiology, Universitat Autònoma de Barcelona (UAB), Bellatera, Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Mas
mesh_terms: D048908:Aliivibrio fischeri / Q000737:chemistry*; D001681:Biological Assay / Q000295:instrumentation*; D004926:Escherichia coli / Q000737:chemistry* / Q000648:ultrastructure; D005292:Ferricyanides / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D010084:Oxidation-Reduction; D010209:Paper; D012987:Soil / Q000737:chemistry; D018675:Toxicity Tests
chemical_list: D005292:Ferricyanides; D012987:Soil; C007931:hexacyanoferrate III
keywords: Bacterial ferricyanide reduction; Chromatic analysis; Microbial respirometry; Non-instrumental analysis; Optical reflectometry; Paper-based toxicity bioassay