Infection Kinetics and Phylogenetic Analysis of vB_EcoD_SU57, a Virulent T1-Like Drexlerviridae Coliphage.

The morphology, infection kinetics, genome sequence and phylogenetic characterization of the previously isolated bacteriophage vB_EcoD_SU57 are presented. The phage vB_EcoD_SU57 was isolated on Escherichia coli strain ECOR57 from the E. coli reference collection and was shown to produce four mm clear plaques with halos. Infection kinetics, as assessed by one-step growth analyses, suggest that vB_EcoD_SU57 is a virulent phage with an adsorption rate of 8.5 × 10-10 mL × min-1, a latency period of 14 min, and a burst size of 13 PFU per bacterium. Transmission electron microscopy confirmed vB_EcoD_SU57 to be a phage that used to be classified as a Siphoviridae phage. Bioinformatics analyses showed that the genome was 46,150 base pairs long, contained 29 genes with predicted protein functions, and 51 open reading frames encoding proteins with unknown function, many of which were gathered in clusters. A putative tRNA gene was also identified. Phylogenetic analyses showed that vB_EcoD_SU57 is a Braunvirinae phage of the newly formed Drexlerviridae family and closely related to T1-like E. coli phages vB_EcoS_ACG-M12 (Guelphvirus) and Rtp (Rtpvirus) as well as the unclassified phages vB_EcoS_CEB_EC3a and ECH1.

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.