A new rapid assay may help growers make faster and more informed decisions right on the farm. Researchers from the University of Massachusetts and Cornell University are developing a test that addresses the challenge of sampling produce and assessing risk in a timely manner. The dipstick would enable rapid detection of Salmonella in agricultural samples in about three hours.
How It Works
“Users simply place a leaf sample in a small plastic bag that contains enzymes and incubate it for about 1.5 hours. Users would then squeeze a small liquid sample through a filter and place it in a tube with bacteriophages—viruses that are harmless to humans but infect specific bacterium, such as Salmonella or E. coli. Some phages are so specific they will only infect one bacterium serotype while others will infect a broader range of serotypes within an individual species. Phages also will only infect and replicate in viable bacteria, ensuring that non-viable organisms are not detected. This distinction is useful if prior mitigation steps, such as chlorination, have already been used. The phages used in the test were engineered to insert a particular gene into the bacteria.” – Center for Produce Safety
“We have been developing dipstick assays for ultra-low detection limits,” the technical abstract, Rapid bacterial testing for on-farm sampling, states. “Our preliminary data suggests that our fluorescent dipstick will have a detection limit of Salmonella spp. cells which makes the test ideal for on-farm use and appropriate federal requirements.”