In the new study, Koo, Daniell and colleagues tried a new approach, combining the antimicrobial peptides with the matrix-degrading enzyme.
To address the prohibitive cost of antimicrobial peptide production, the researchers turned to Daniell's plant-based protein drug production platform. The process entails bombarding a plant leaf with gold particles coated in a cloned gene in order to reprogram the chloroplasts to synthesize the associated protein. In this case, the researchers coaxed plants to produce two different antimicrobial peptides, retrocyclin and protegrin. Both peptides have complex secondary structures, making them expensive to produce in the lab by traditional means. But the researchers found they could literally grow them in Daniell's greenhouse and faithfully replicate their unique secondary structures in the plant's leaves.
They then tested whether the plant-made agents could prevent creation of a biofilm. They exposed a saliva-coated tooth-like surface to the plant-made protegrin for 30 minutes, then exposed the surface to S. mutans cells along with sugar and found that it significantly impaired the ability of the bacterium to form a biofilm compared to an untreated surface.