Recombinant spider silk coatings functionalized with enzymes targeting bacteria and biofilms

Bacteria forming biofilms on surgical implants is a problem that might be alleviated by the use of antibacterial coatings. In this article, recombinant spider silk was functionalized with the peptidoglycan degrading endolysin SAL-1 from the staphylococcal bacteriophage SAP-1 and the biofilm-matrix-degrading enzyme Dispersin B from Aggregatibacter actinomycetemcomitans using direct genetic fusion and/or covalent protein-protein fusion catalyzed by Sortase A. Spider silk assembly and enzyme immobilization was monitored using quartz crystal microbalance analysis. Enzyme activity was investigated both with a biochemical assay using cleavage of fluorescent substrate analogues and bacterial assays for biofilm degradation and turbidity reduction. Spider silk coatings functionalized with SAL-1 and Disperin B were found to exhibit bacteriolytic effect and inhibit biofilm formation, respectively. The strategy to immobilize antibacterial enzymes to spider silk presented herein show potential to be used as surface coatings of surgical implants and other medical equipment to avoid bacterial colonization.