E. Coli Detection
E. Coli Detection - Related Videos
08:16
Detection of Live Escherichia coli O157:H7 Cells by PMA-qPCR
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Cited by 11 •
2014
A qPCR assay was developed for detection of Escherichia coli O157:H7 targeting a unique genetic marker, Z3276. The qPCR was combined with propidium monoazide (PMA) treatment for live cell detection. This protocol has been modified and adapted to a 96-well plate format for easy and consistent handling of numerous...
01:28
Phage-Based Microfluidic Assay for Detecting Viable E. coli in Water Samples
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2026
Begin with a contaminated water sample likely to harbor fecal coliforms, including E. coli.Perform a serial dilution in distilled water to reduce turbidity and microbial load.Mix the desired diluted sample with the nutrient medium and load it into a microfluidic chip.Use vacuum filtration to capture bacteria on a membrane within the serpentine channel of the chip.Add nutrient medium to the upper chamber and incubate to enhance bacterial recovery.Replace the medium with a solution of E.
04:33
Gel Electrophoresis and Northern Blotting to Detect tRNA Charging Levels in E. coli
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2025
Source: Stenum, T. S., et al. Quantification of the Abundance and Charging Levels of Transfer RNAs in Escherichia coli. J. Vis. Exp. (2017)This video demonstrates the use of gel electrophoresis and northern blotting to detect and compare the charging levels of transfer RNAs in E. coli by separating aminoacylated and deacylated forms.
12:50
Colorimetric Paper-based Detection of Escherichia coli, Salmonella spp., and Listeria monocytogenes from Large Volumes of Agricultural Water
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Cited by 24 •
2014
A protocol involving integrated concentration, enrichment, and end-point colorimetric detection of foodborne pathogens in large volumes of agricultural water is presented here. Water is filtered through Modified Moore Swabs (MMS), enriched with selective or non-selective media, and detection is performed using paper-based analytical devices (µPAD) imbedded with bacterial-indicative colorimetric substrates.
07:22
Optical Detection of E. coli Bacteria by Mesoporous Silicon Biosensors
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Cited by 16 •
2013
A label-free optical biosensor for rapid bacteria detection is introduced. The biosensor is based on a nanostructured porous Si, which is designed to directly capture the target bacteria cells onto its surface. We use monoclonal antibodies, immobilized onto the porous transducer, as the capture probes. Our studies demonstrate the applicability of these biosensors for the detection of low bacterial concentrations within minutes with no prior sample processing (such as cell lysis).
FAQs
Culture-based and molecular approaches answer different measurement questions. Culture methods grow viable cells on selective media, so their results are tied to organisms capable of growth under the test conditions. PCR instead amplifies species-specific DNA, which indicates genetic material rather than necessarily viable cells. This distinction matters when interpreting environmental monitoring data and comparing results across methods.
Membrane filtration concentrates microorganisms from an environmental sample onto a filter, making them easier to examine. The retained material can then support growth on selective media or contribute to a detection workflow, depending on the method. This concentration step is especially useful when organisms are dispersed through water and must be collected before measurement.
These substrates detect enzyme activity rather than relying solely on visible colony growth or DNA amplification. They provide an alternative analytical route for identifying and measuring target organisms in environmental samples. Compared with PCR, the approach does not center on amplifying species-specific DNA, while its use alongside culture methods broadens the available monitoring strategies.
Method choice determines what a positive result represents. Selective-media procedures focus on viable cells that grow under the test conditions, whereas PCR-based analysis detects species-specific DNA. Enzyme-substrate methods provide evidence through biochemical activity. Treating these outputs as interchangeable could obscure whether a result reflects living organisms, genetic material, or enzyme activity.
A workflow begins with an environmental sample such as water, soil, food, or another relevant matrix. Depending on the chosen approach, the laboratory may concentrate microorganisms by membrane filtration, place viable cells on selective media, expose the sample to chromogenic or fluorogenic substrates, or amplify species-specific DNA by PCR. The resulting measurement is interpreted according to the method used.
It supports assessment of drinking water, recreational waters, wastewater, and agricultural runoff. Results can help identify fecal contamination, evaluate microbial water quality, and inform remediation or regulatory decisions. Applying the method across these settings allows laboratories to compare contamination concerns among public, waste-related, and agricultural environments while keeping interpretation tied to the measurement approach.