Decoy EPS layers for trapping and killing bacteria

Here we report a novel strategy using bacterial extracellular polymeric substances (EPS) as decoys to enhance bacterial adhesion and contact-based antimicrobial activity. EPS extracted from Staphylococcus aureus and Bacillus subtilis was used to coat wafers as a conditioning layer to alter surface properties and facilitate bacterial aggregation. Results show that EPS downregulates quorum sensing-related genes (agr and atl in Staphylococcus aureus by 80.5 % and 86.6 %, respectively; fliC in Escherichia coli by ~58.3 %), suggesting that EPS facilitates energy-efficient adhesion independent of quorum sensing signals. Loading antibiotics (erythromycin, linezolid, levofloxacin) into the EPS layer further enhances adhesion and contact killing. Especially, the surfaces loaded with a levofloxacin concentration of 2 μg/mL exhibit a significant antimicrobial effect. For Staphylococcus aureus, the antimicrobial rate reaches 83.66 % after 4 h incubation but drops to 39.9 % after 8 h incubation. In contract, Escherichia coli exhibits greater sensitivity, with antibacterial activity increasing to 92.97 % after 8 h incubation. Laser confocal microscopy characterization further reveals that the antibiotic-loaded EPS surfaces possess remarkable contact bacteria-killing activity. Our results show the promising recruiting-killing efficacy of the antibiotics-loaded EPS against bacteria, which would give insight into exploring new antibacterial strategies for enhanced contact-antibacterial performances.