Scientists who have developed a way of using viruses to kill colonies of the common disease-causing bacteria Pseudomonas aeruginosa, say it could be adapted to sanitize water treatment plants and help fight deadly antibiotic-resistant bacteria or so-called “superbugs”.
In a paper published recently in the journal Biotechnology and Bioengineering, Zhiqiang Hu, associate professor in the department of civil and environmental engineering at the University of Missouri, and Yanyan Zhang, a recent graduate of the department, describe how they used a group of viruses known as bacteriophages to tackle the challenge of destroying bacterial biofilms.
The word “bacteriophage” comes from bacteria and the Greek for devour. These viruses attack bacteria from the inside. They inject the bacteria with genes and hijack their protein-making processes to replicate the virus instead.
Hu says in a press statement:
“Our experiment was the first to use bacteriophages in conjunction with chlorine to destroy biofilms, which are layers of bacteria growing on a solid surface.”
He explains that viruses are useful tools for destroying bacteria because you can make them select only the harmful ones and leave the beneficial ones, such as those that break down waste in water treatment plants, alone.
“Hence, viruses could be used to get rid of pathogenic bacteria in water filters that would otherwise have to be replaced. They could save taxpayers’ money by reducing the cost of cleaning water,” Hu adds.
Bacteria pose real challenges when they form biofilms, a growing concern in many areas. While a good dose of chlorine kills off the ones in the outer crust, the ones on the inside stay sheltered and survive, but if you infect the colony with bacteriophage viruses, they spread and reach all the bacterial cells.
For their study, Hu and Zhang used “a mixture of RNA bacteriophages isolated from municipal wastewater” against Pseudomonas aeruginosa biofilms.
They found the most effective solution was to use chlorine together with bacteriophages.
Chlorine alone only killed 40% of the bacteria, bacteriophages alone only killed 89%, but bacteriophages and chlorine together got rid of 97% of the biofilms they tested them on within 5 days of exposure.
” Laser scanning confocal microscopy supplemented with electron microscopy indicated that the combination treatment resulted in biofilms with lowest cell density and viability,” write Hu and Zhang, concluding that:
” These results suggest that the combination treatment of phages and chlorine is a promising method to control and remove bacterial biofilms from various surfaces.”
Hu says the methods they used to kill the Pseudomonas aeruginosa bacteria could be used against other dangerous bacteria, “even those that have developed resistance to antibiotics“.
He explains that not only are viruses better at targeting specific species of bacteria, they are also easier to produce than the enzymes currently made to attack biofilms.
“Our work opened the door to a new strategy for combating the dangers and costs of bacterial biofilms. The next step is to expand our experiment into a pilot study,” Hu adds.
Written by Catharine Paddock PhD