Production and evaluation of the utility of novel phage display-derived peptide ligands to Salmonella spp. for magnetic separation

Abstract

Aims: The objectives of this study were to produce Salmonella-specific peptide ligands by phage display biopanning and evaluate their use for magnetic separation (MS). Methods and Results: Four-phage display biopanning rounds were performed, and the peptides expressed by the two most Salmonella-specific (on the basis of phage-binding ELISA results) phage clones, MSal020401 and MSal020417, were chemically synthesized and coupled to MyOne™ tosylactivated Dynabeads®. Peptide capture capability for whole Salmonella cells from nonenriched broth cultures was quantified by MS + plate counts and MS + Greenlight™ detection and compared to capture capability of anti-Salmonella (antibody-coated) Dynabeads®. MS + Greenlight™ gave a more comprehensive picture of capture capability than MS + plate counts and showed that Peptide MSal020417-coated beads exhibited at least similar, if not better, capture capability to anti-Salmonella Dynabeads® (mean capture values of 36·0 ± 18·2 and 31·2 ± 20·1%, respectively, over Salmonella spp. concentration range 3 × 101-3 × 106 CFU ml-1) with cross-reactivity of ≤1·9% to three other foodborne pathogens: Escherichia coli, Listeria monocytogenes and Campylobacter jejuni. Conclusions: One of the phage display-derived peptide ligands was demonstrated by MS + Greenlight™ to be a viable antibody alternative for MS of Salmonella spp. Significance and Impact of the Study: This study demonstrates an antibody-free approach to Salmonella detection and opens substantial possibilities for more rapid tests for this bacterium. © 2013 The Society for Applied Microbiology.