title: Colorimetric paper-based detection of Escherichia coli, Salmonella spp., and Listeria monocytogenes from large volumes of agricultural water.
abstract: This protocol describes rapid colorimetric detection of Escherichia coli, Salmonella spp., and Listeria monocytogenes from large volumes (10 L) of agricultural waters. Here, water is filtered through sterile Modified Moore Swabs (MMS), which consist of a simple gauze filter enclosed in a plastic cartridge, to concentrate bacteria. Following filtration, non-selective or selective enrichments for the target bacteria are performed in the MMS. For colorimetric detection of the target bacteria, the enrichments are then assayed using paper-based analytical devices (µPADs) embedded with bacteria-indicative substrates. Each substrate reacts with target-indicative bacterial enzymes, generating colored products that can be detected visually (qualitative detection) on the µPAD. Alternatively, digital images of the reacted µPADs can be generated with common scanning or photographic devices and analyzed using ImageJ software, allowing for more objective and standardized interpretation of results. Although the biochemical screening procedures are designed to identify the aforementioned bacterial pathogens, in some cases enzymes produced by background microbiota or the degradation of the colorimetric substrates may produce a false positive. Therefore, confirmation using a more discriminatory diagnostic is needed. Nonetheless, this bacterial concentration and detection platform is inexpensive, sensitive (0.1 CFU/ml detection limit), easy to perform, and rapid (concentration, enrichment, and detection are performed within approximately 24 hr), justifying its use as an initial screening method for the microbiological quality of agricultural water.
authors: Department of Animal Science, University of Wyoming; bbisha@uwyo.edu.
authors: Bledar
authors: B
authors: Bisha
authors: Department of Chemistry, Colorado State University.
authors: Jaclyn A
authors: JA
authors: Adkins
authors: Department of Environmental and Radiological Health Sciences, Colorado State University.
authors: Jana C
authors: JC
authors: Jokerst
authors: Department of Animal Science, University of Wyoming.
authors: Jeffrey C
authors: JC
authors: Chandler
authors: Department of Animal Sciences, Colorado State University.
authors: Alma
authors: A
authors: Pérez-Méndez
authors: Department of Animal Sciences, Colorado State University.
authors: Shannon M
authors: SM
authors: Coleman
authors: Department of Plant Sciences, University of California, Davis.
authors: Adrian O
authors: AO
authors: Sbodio
authors: Department of Plant Sciences, University of California, Davis.
authors: Trevor V
authors: TV
authors: Suslow
authors: Department of Food Science and Human Nutrition, Citrus Research and Education Center, University of Florida.
authors: Michelle D
authors: MD
authors: Danyluk
authors: Department of Chemistry, Colorado State University.
authors: Charles S
authors: CS
authors: Henry
authors: Department of Food Science and Agricultural Chemistry, McGill University.
authors: Lawrence D
authors: LD
authors: Goodridge
mesh_terms: D057914:Agricultural Irrigation; D000383:Agriculture / Q000379:methods*; D003124:Colorimetry / Q000379:methods*; D004926:Escherichia coli / Q000302:isolation & purification*; D008089:Listeria monocytogenes / Q000302:isolation & purification*; D010209:Paper; D012475:Salmonella / Q000302:isolation & purification*; D014871:Water Microbiology