Recombinant Phage Tail Fiber Protein Gp47 Enables Broad-Spectrum Fluorescent Detection of Pseudomonas aeruginosa Strains

Pseudomonas aeruginosa ( P. aeruginosa ) has long been one of the leading opportunistic pathogens responsible for serious healthcare-associated infective diseases. Development of rapid and accurate detection techniques for this pathogen is highly desired to achieve efficient prevention and control. This study developed a fluorescent detection technique targeting this pathogen by using recombinant phage tail fiber protein Gp47 as the recognition element. This protein was identified from a phage PAB1 isolated from hospital wastewater through genomic sequencing and bioinformatic analysis. It was then produced in its functional form via recombinant expression and purification. Gp47 exhibited broad-spectrum binding capability toward P. aeruginosa strains, recognizing all 30 clinical isolates tested, while completely lacking lytic activity. Thus, it effectively overcame the key limitations of the whole phage, including the narrow host range and tendency to lyse target bacteria. A sandwich method was constructed to detect P. aeruginosa by using Gp47 conjugated magnetic beads as capture carriers and fluorescein isothiocyanate labeled antimicrobial peptide as signal reporter. The method responded to P. aeruginosa linearly from 3.2 × 10 2 to 3.2 × 10 6 CFU/mL, with a limit of detection of 109 CFU/mL and ideal specificity. It has been employed for detecting P. aeruginosa in complex matrices such as physiological saline, human urine, and milk powder with acceptable recoveries ranging from 71.23% to 110.87%. This work provides a high-performance recognition element for P. aeruginosa and helps develop valuable diagnostic tools for infective diseases.