Phage-Modified\nClear Hydrogel for Simultaneous Detection\nof Multiple Bacteria

The proliferation speed of live foodborne pathogens is\nfast. A\nsmall number of pathogens will have a great impact on food and the\nenvironment if positive samples are not detected timely. In this study,\ntransparent porous hydrogel stir bars, modified by two different phages\n(corresponding to two different bacteria (Escherichia\ncoli and <i>Hafnia sp</i>)), have been developed\nfor rapid detection of foodborne bacteria. A large number of samples\ncan be analyzed simultaneously with a small animal live imager device\nto screen out the positive samples, while an adenosine triphosphate\n(ATP) bioluminescence sensor can be used to quantify the number of\nbacteria in the positive samples. The phage has good specificity and\ncapture ability to bacteria, which makes the method highly sensitive.\nIn addition, the use of multiple phages also enables the method to\ndetect multiple bacteria simultaneously. The three-dimensional structure\nof the hydrogel allows it to modify more phages, and its transparent\nnature also allows the inside bioluminescence to be detected. Both\ncan enhance the sensitivity of the detection. Finally, the reagents\nneeded for bioluminescence, such as d-luciferin, can also\nbe preencapsulated in the hydrogel, thus simplifying the detection\nstep. Under the best conditions, the detection range of the method\nis 10<sup>2</sup>–10<sup>8</sup> CFU·mL<sup>–1</sup>, and the limit of detection is 30 CFU·mL<sup>–1</sup> within 11 min. The test results of actual samples show that there\nis no difference between using the method developed through this study\nand the traditional plate counting method, but the detection time\nis greatly shortened.