Twofold enhanced dispersin B activity by N-terminal fusion to silver-binding peptide for biofilm eradication

Dispersin B (DspB) has shown a great potential for the hydrolysis of polymeric β-1,6-N-acetyl-d-glucosamine (PNAG) to disperse the biofilms formed by various bacteria but with no killing activity. Here we have investigated whether a silver-binding peptide (AgBP) fused to DspB can induce the in situ formation of silver nanoparticles (AgNP) and conjugated to the structure of DspB so that the bacteria cells released from the dispersed biofilm will be killed by the conjugated AgNP. However, the desired conjugate could be obtained because of the silver ions itself was found to precipitate DspB. But, the fusion of AgBP2 to DspB (AgBP2-DspB) could generate at least 2 fold higher activity against soluble substrate 4-nitrophenyl N-acetyl-β-D-glucosaminide (NP-GlcNAc). By applying to a preformed Staphylococcus epidermidis biofilm, AgBP2-DspB could clear 69% of the biofilm while only 37% could be cleared by DspB as observed by fluorescent microscope. As measured by crystal violet staining, biofilm could be eradicated to the same extent by loading AgBP2-DspB activity level approximately 20 fold lower than that of DspB. The biofilm formation could be prevented on a AgBP2-DspB immobilized surface as observed by confocal laser microscope.