A novel phage receptor-binding protein as a rapid and specific biorecognition tool for detecting Campylobacter jejuni

Issues related to multidrug resistance require rapid action against bacterial contamination and foodborne illnesses. In this regard, rapid, specific, and highly sensitive detection of Campylobacter jejuni is important for infection control, considering the growing, relatively uncontrolled incidence of campylobacteriosis. In this study, we developed a novel approach for detecting C. jejuni using a bacteriophage receptor-binding protein (RBP). A tail protein (RBP_PC10) was identified and characterized in the vB_CjeM-PC10 phage genome. DNA encoding the RBP_PC10 protein was synthesized, fused with the mCherry gene, cloned, and expressed as recombinant red-fluorescent RBP_PC10 (rRBP_PC10). Functional analyses were performed by fluorescence microscopy and spectrofluorometry. The recombinant protein was stable at alkaline pH, and it showed high and stable performance at pH 8. Fluorescence detection using the protein showed a good linear correlation between fluorescence intensity and the cell concentration of C. jejuni (10⁴-10⁸ CFU/mL), with a lower detection limit of 100 CFU/mL (2 log₁₀ CFU/mL) within 30 min in broth and in the presence of chicken skin. In conclusion, fluorescence detection using rRBP_PC10 is expected to provide a simple, rapid, specific, sensitive, and inexpensive system for detection of C. jejuni.