Biofilms may shelter pathogenic or problematic microorganisms that are difficult to eradicate due to insufficient penetration of antimicrobial chemicals. Here, we demonstrate the potential for efficient microbial suppression in biofilms, using broad-host-range phages attached to magnetic microspheres that facilitate biofilm penetration under a magnetic field. The polyvalent phage PEL1 (Podoviridae family) was immobilized to magnetic microspheres that had been coated with chitosan (and thus functionalized with amino groups); this facilitated conjugation with phages via covalent bonding through amide linkages. This approach enabled loading (5.2 ± 0.7) × 103 PFU of phage per 1-µg chitosan- nanomagnetite microsphere (CS-Fe3O4). The plaque formation capability of PEL1-CS-Fe3O4 on the lawn of Pseudomonas aeruginosa PA01 and Escherichia coli C3000 was significantly higher than that of phages conjugated with a similar microsphere that had been functionalized with carboxyl groups (99.1 % vs 3.2 % Petri dish area of infection). In newly established mixed-species biofilm, PEL1-CS-Fe3O4 achieved 88.1±2.9 % bacterial removal efficiency on glass surface after 6 h treatment. Enhanced biofilm penetration by the phage-microsphere complex and control of its migration direction was achieved through magnetic field control. Overall, this approach could extend the application of phages for microbial control by enhancing their delivery to relatively inaccessible locations within biofilms.

Enhanced biofilm penetration for microbial control by polyvalent phages conjugated with magnetic nanoparticles

254th National Meeting (2017)

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