New approach for microbial control

Sri Lanka, Bhutan, Nepal and Bangladesh

Researchers at Rice University and the University of Science and Technology of China have developed a new approach for treating water system contaminated with microbes. Magnetic nanoparticle clusters had the ability to control microbial growth as they could punch through the biofilms. They carry bacteriophages and deliver them to targets that generally resist chemical disinfection. These were developed through Rice's Nanotechnology-Enabled Water Treatment (NEWT) Engineering Research Center.

Usually, bacteriophages get dispersed in solution, fails to penetrate through biofilms and allow bacteria to grow in solution cause corrosion of metal. This mechanism makes the water distribution systems problem costly. To overcome these complications, it was found that weak magnetic field could draw bacteriophages into the biofilms. This study carried out by Pedro Alvarez and colleagues from Rice University is explained in detail in the Royal Society of Chemistry's Environmental Science: Nano.

Alvarez reported that the magnetized virus emerged from the convergence of nanotechnology and virology. It has a great potential to overcome the difficulties faced to eradicate biofilms that do not generate harmful disinfection byproducts.

Pingfeng Yu, the co-lead author, reported that biofilms could be of use in some wastewater treatment or industrial fermentation reactors owing to their enhanced reaction rates and resistance to exogenous stresses. "However, biofilms can be deleterious in water distribution and storage systems as they protect pathogenic microorganisms that pose potential public health concerns and may also contribute to corrosion and associated economic losses." 

The researchers used polyvalent bacteriophage to target lab-grown films that contained infectious disease-causing strains of Escherichia coli and antibiotic resistant Pseudomonas aeruginosa.

The bacteriophages were made to combine with the clusters of sulfur, carbon as well as iron oxide. An additional modification was done with amino molecules to facilitate phage attachment with clusters head and exposed the tails to infect bacteria. They applied a weak magnetic field to draw them into the biofilm and disrupt it.

Researchers found that nanoclusters destroyed around 90% of E. coli and P. aeruginosa in a test 96-well plate and less than 40% on a plate with phages alone. Although there is a chance for developing resistance to phages, the ability to quickly disrupt biofilms would make that more difficult.

Alvarez concluded that the researchers are working on phage "cocktails" that would combine certain molecules with multiple types of phages and/or antibiotics to avert resistance.