Researchers have found a way to use magnetic nanoparticle clusters to punch through biofilms to reach bacteria that can foul water treatment systems.

The nanoclusters then deliver bacteriophages—viruses that infect and propagate in bacteria—to destroy the bacteria, usually resistant to chemical disinfection.

Without the pull of a magnetic host, these “phages” disperse in solution, largely fail to penetrate biofilms and allow bacteria to grow in solution and even corrode metal, a costly problem for water distribution systems.

The Rice University lab of environmental engineer Pedro Alvarez and colleagues in China developed and tested clusters that immobilize the phages. A weak magnetic field draws them into biofilms to their targets.

“This novel approach, which arises from the convergence of nanotechnology and virology, has a great potential to treat difficult-to-eradicate biofilms in an effective manner that does not generate harmful disinfection byproducts,” Alvarez says.

Biofilms can be beneficial in some wastewater treatment or industrial fermentation reactors owing to their enhanced reaction rates and resistance to exogenous stresses, says graduate student and co-lead author Pingfeng Yu.


Energy GridA new study published by researchers from Michigan State University reveals a new biofilm that can feed on waste and produce energy as a byproduct.

The novel biofilm was discovered and patented by ECS member and Science for Solving Society’s Problems grantee Gemma Reguera.

(MORE: Listen to our Science for Solving Society’s Problems Round Table podcast to hear how Reguera is applying microbial science to solving pressing issues in water and sanitation.)

Reguera’s biofilm works in a way very similar to the electric grid, where each cell acts as an individual power plant – generating electricity to be delivered to the underlying electrodes using a sophisticated microbial network. One part of that network, the cytochromes, act as transformers and towers that supply electricity to a city. The other part, the pili, acts as the powerlines connecting the towers so all have access to the grid.

“The pili do all of the work after the first 10 layers, and allow the cells to continue to grow on the electrode, sometimes beyond 200 cell layers, while generating electricity,” Reguera says, associate professor of microbiology at Michigan State University. “This is the first study to show how electrons can travel such long distances across thick biofilms; the pili are truly like powerlines, at the nanoscale.”

Each individual part of the biofilm is essential to the development of the working whole, much like the power grid.