Thermochromic temperature of polydiacetylene has been reported to coincide with the melting temperature of its lipidic monomers, indicating that the solid-to-liquid phase transition of monomers is linked to the color change. In this work, we study a hypothesis that peptide-induced chromism is similarly mediated by the lipid phase transition as many antimicrobial peptides are known to modulate the melting temperature of lipids.