Engineers and biochemists at McMaster University have developed a biogel test that allows untrained users to detect bacterial contamination in fluids. The gel changes color when it encounters bacteria like E. coli and Listeria, using harmless bacteriophages embedded in the gel to target specific bacteria in samples such as lake water, urine, or milk, even at low concentrations. Bacteriophages are the most common form of life on Earth, with each type targeting a specific bacteria.
In the test, described in a new paper published in the journal Advanced Materials, bacteriophages target and attack specific bacteria in a sample, causing the bacteria to release microscopic materials that trigger a visible color change, indicating contamination. If the sample is clean, the color remains unchanged. This process provides results in hours, much faster than traditional lab cultures, which can take up to two days.
The new test can be adapted to any bacterium by using bacteriophages and DNA probes that specifically target microbes such as listeria and salmonella. Such a test could have provided early and accurate detection in the recent listeria contamination of plant-based milk that killed two, sickened 10 and caused wide recalls in Canada.
Testing for contamination in complex fluids such as milk, blood or urine is especially challenging, making simple, reliable alternatives such as the new test very useful. This technology can be helpful in rapidly limiting outbreaks when people have something in their fridge that they are concerned about. This test can let them know if it is safe for consumption.
As the paper’s lead author Hannah Mann, a PhD student in chemical engineering and bioengineering says “Once we have the appropriate approvals and partnerships to move this test to market, it could be very useful in many settings. About 12 per cent of Canadians don’t have access to municipal piped water, for example, and this could bring them a lot of peace of mind.”.
Extracted from Research Article “Bacteriophage-Activated DNAzyme Hydrogels Combined with Machine Learning Enable Point-of-Use Colorimetric Detection of Escherichia coli”
published in Advanced Materials – 26 November 2024 – 24 November 2021.
Keywords
biogel test, bacterial contamination, fluids, E. coli, Listeria, bacteriophages, lake water, urine, milk, low concentrations, Advanced Materials, DNA probes, Salmonella, early detection, plant-based milk, listeria contamination, Canada, complex fluids, outbreaks, safety, consumption, bioengineering