(6g) Universal Cell Detection By Immobilized Antimicrobial Peptide Plantaricin

Antimicrobial peptides (AMPs) are an essential part of innate immune response of many organisms and they have demonstrated direct antimicrobial activity against a large spectrum of microorganisms. These peptides exert their activity by binding to surface components of target cells and causing membrane disruption. The semi-selective cell recognition and binding property of AMPs make them potentially valuable detection agents. Plantaricin-423 is a Class-IIa bacteriocin and display bactericidal activities against several foodborne pathogens and spoilage gram positive bacteria. The goal of this study was to investigate the potential of using immobilized plantaricin for capture of a broad variety of microbial species in a biosensor format. The peptides used for immobilization consist of N-terminal domain of Pln-423 (first 18 amino acids) and an additional cysteine residue (Pln-18C) to form a disulfide bond between thiol groups of the silanized glass surface and the peptide. The capture capability of peptide-immobilized slides was tested with Bacillus coagulans, Enterococcus hirae, Escherichia coli, Staphylococcus epidermidis, Listeria innocua and Mycobacterium smegmatis cells representing both Gram positive and Gram negative bacteria families. Our results showed that Pln-18C is able to recognize and capture cells of all seven species that were tested. The cell binding was observed to occur within five minutes of incubation and the binding levels were similar for all cell types except M. smegmatis which was lower compared to other species. The detection limit for L. innocua 33090 was determined to be 5x10⁴ to 1x10⁵cells/ml depending on the immobilized peptide concentration. We have also evaluated the viability of surface-bound L. innocua 33090 and E. coli JE5505 cells and observed that immobilized Pln-18C maintained its anti-listerial activity, however, it did not cause any membrane disruption of E. coli cells as expected. Our results demonstrate the potential of utilizing antimicrobial peptides, specifically Pln-18C, in biosensors for pathogen detection and creating antimicrobial surfaces against Listeria species. Moreover, in combination with other cell-binding AMPs, a higher number of different target species, from food-borne pathogens to biodefense agents, can be captured on a more stable, economic and robust platform.