Rapid detection of pathogenic bacteria and screening of phage-derived peptides using microcantilevers

We report the use of an array of microcantilevers to measure the specific binding of Salmonella to peptides derived from phage display libraries. Selectivity of these phage-derived peptides for Salmonella spp. and other pathogens (Listeria monocytogenes and Escherichia coli) are compared with a commercially available anti-Salmonella antibody and the antimicrobial peptide alamethicin. A Langmuir isotherm model was applied to determine the binding affinity constants of the peptides to the pathogens. One particular peptide, MSal 020417, demonstrated a higher binding affinity to Salmonella spp. than the commercially available antibody and is able to distinguish among eight Salmonella serovars on a microcantilever. A multiplexed screening system to quickly determine the binding affinities of various peptides to a particular pathogen highly improves the efficiency of the peptide screening process. Combined with phage-derived peptides, this microcantilever-based technique provides a novel biosensor to rapidly and accurately detect pathogens and holds potential to be further developed as a screening method to identify pathogen-specific recognition elements.