Rapid detection and identification of bacteria is important for human health, biodefense, and food safety. Small arrays of different antimicrobial peptides (AMPs) enable the identification of lipopolysaccharide (LPS) samples from a variety of bacterial species and strains. A model system for examining how peptide presentation affects LPS detection is the sheep myeloid antimicrobial peptide (SMAP-29), which contains a helix-turn-helix motif. Varying the cysteine attachment site on SMAP-29 controls the three-dimensional presentation of the peptide on the surface, altering the ability of the peptide to discriminate between LPS samples. A small array of only SMAP-29 variants-and no other peptides-is capable of discriminating among LPS samples from multiple bacterial species, as well as between different strains within the same species, with high accuracy.