Comparison of enzymes and amyloid hexapeptide for antibiofilm activity

Abstract This study screened and evaluated a panel of enzymes for their capacities to inhibit biofilm formation and disperse established biofilms, and compared their efficiencies with our previously developed amyloid hexapeptide GI6. Seven enzymes (mutanase, dextranase, collagenase I, dispase II, cellulase, lysozyme, and Dispersin B) and GI6 were evaluated against Streptococcus mutans (S. mutans) for anti-biofilm, bactericidal, and biofilm eradication activities. A human enamel block caries model was established, and the anti-biofilm and anti-caries effects were characterized by TEM, CLSM, SEM, and micro-CT. Among the seven enzymes under the tested conditions, only DspB (0.25 mg/mL) showed anti-biofilm activity. Immunofluorescence staining confirmed the presence of the DspB substrate poly‑N‑acetylglucosamine (PNAG) in S. mutans biofilms. Like GI6, DspB lacked bactericidal activity and could not disperse established biofilms. SEM and TEM confirmed reduced extracellular polysaccharides (EPS) and non-bactericidal effects for both. In the human enamel block caries model, both DspB and GI6 inhibited biofilm formation and reduced enamel demineralization, with GI6 showing better efficacy at a lower concentration. These findings indicate that most tested enzymes are ineffective against S. mutans biofilm under the tested conditions, and that DspB inhibits biofilm formation only at higher concentrations than GI6, suggesting that GI6 exhibits superior antibiofilm efficacy and anti-caries activity under the tested conditions. Future efforts in caries prevention may benefit from more effective biofilm-disrupting agents. Key points • Both DspB and GI6 decrease biofilm formation, but fail to disrupt mature biofilms. • GI6 suppresses biofilm formation and enamel demineralization at lower concentrations than DspB. • Agents that more efficiently targeting EPS in mature biofilms would have caries superior prevention value.