Magnetized bacteriophages successfully punch through biofilms to reach targets.

Biofilms are where bacteria join together on a surface and start to form a protective matrix around their group, examples include dental plaque, a slimy biofilm of bacteria forming on the surfaces of teeth.  Due to their structure biofilms may shelter problematic microorganisms that are difficult to eradicate due to the hindered penetration of antimicrobial chemicals.  Now, a study led by researchers Rice University develops magnetic bacteriophages, viruses known to infect bacteria, in nanoclusters with the power to punch through biofilms to reach bacteria fouling water treatment systems.  The team states their nanoclusters deliver bacteriophages to targets shown to generally resist chemical disinfection.  The study is published in the journal Environmental Science: Nano.

Previous studies show biofilms can be beneficial in some wastewater treatment or industrial fermentation reactors owing to their enhanced reaction rates and resistance to exogenous stresses.  However, biofilms can be very harmful in water distribution and storage systems since they can shelter pathogenic microorganisms posing significant public health concerns, as well as contributing to corrosion and its associated economic losses.  Bacteriophages have been investigated as a treatment solution, however, they disperse in solution and largely fail to penetrate biofilms.  The current study investigates nanoclusters capable of immobilizing bacteriophages, using a weak magnetic field to draw them into biofilms to their targets.

The current study utilizes bacteriophages which are polyvalent, meaning they’re able to attack more than one type of bacteria, to target lab-grown films containing Escherichia coli (E. coli) and P. aeruginosa, which is prone to antibiotic resistance.  The bacteriophages are combined with amino-modified nanoclusters of carbon, sulfur, and iron oxide. Results show the amino coating prompts the bacteriophages to bond with the clusters head-first, leaving their infectious tails exposed and able to infect bacteria.

Data findings show a relatively weak magnetic field pushes the nanoclusters into the film and disrupts it. Results show the bacteriophage-nanoclusters effectively killed E. coli and P. aeruginosa in over 90 percent of the film.  The group notes bacteria may still develop resistance to bacteriophages, however, the ability to quickly disrupt biofilms would make this more difficult.  The lab concludes their novel approach, a convergence of nanotechnology and virology, has great potential to treat difficult-to-eradicate biofilms in an effective manner without producing harmful disinfection byproducts.

The team surmises their study develops bacterial suppression using bacteriophages attached to nanoclusters with the ability to penetrate biofilms under a relatively small magnetic field.  For the future, the researchers state they are now working on phage cocktails combining multiple types of bacteriophages and/or antibiotics with the particles to inhibit resistance.

Source: Rice University

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