Phage T4-based colorimetric sensing material and its application to develop a time-dependent bacteria sensing platform for long-term detection of food contamination

Abstract

Herein, we have developed a new type of bacteria-sensing platform for the naked-eye detection of Escherichia coli (E. coli) via a one-spot sample injection process. The platform comprised chlorophenol red-β-d-galactopyranoside (CPRG), isopropyl β-d-thiogalactopyranoside (IPTG), bacteriophages and two carbohydrates namely, maltodextrin and trehalose. CRPG and IPTG detected the β-galactosidase released from the bacteria and enhance its productivity, respectively. Bacteriophages were used as bioreceptors, and two carbohydrates protected phages during thermal process enabling long-term use of the platform. The developed material was characterized using scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy to determine the presence of the phages in the microcapsules. The detection property of the sensing material was examined using different strains of E. coli. Cold water-soluble guar gum was used as the stable gel matrix to increase the reactivity of platform toward samples stored at low temperature. The final prototype was tested using food samples containing different E. coli strains to demonstrate its food applicability with long-term use. This approach may provide an efficient and feasible phage-based sensing platform for the detection of bacterial contamination in food samples.