Phage-Modified Clear Hydrogel for Simultaneous Detection of Multiple Bacteria

The proliferation speed of live foodborne pathogens is fast. A small number of pathogens will have a great impact on food and the environment if positive samples are not detected timely. In this study, transparent porous hydrogel stir bars, modified by two different phages (corresponding to two different bacteria (<i>Escherichia coli</i> and <i>Hafnia sp</i>)), have been developed for rapid detection of foodborne bacteria. A large number of samples can be analyzed simultaneously with a small animal live imager device to screen out the positive samples, while an adenosine triphosphate (ATP) bioluminescence sensor can be used to quantify the number of bacteria in the positive samples. The phage has good specificity and capture ability to bacteria, which makes the method highly sensitive. In addition, the use of multiple phages also enables the method to detect multiple bacteria simultaneously. The three-dimensional structure of the hydrogel allows it to modify more phages, and its transparent nature also allows the inside bioluminescence to be detected. Both can enhance the sensitivity of the detection. Finally, the reagents needed for bioluminescence, such as d-luciferin, can also be preencapsulated in the hydrogel, thus simplifying the detection step. Under the best conditions, the detection range of the method is 10²-10⁸ CFU·mL^-1, and the limit of detection is 30 CFU·mL^-1 within 11 min. The test results of actual samples show that there is no difference between using the method developed through this study and the traditional plate counting method, but the detection time is greatly shortened.