Using a virus to purify water sounds like the premise to a disaster film. But, according to researchers from the University of the Sunshine Coast (USC), it’s not only safe, but it could also make tapwater taste better.
The research focusses on an order of bacteria called actinomycetes. These bacteria are common soil and other organic matter, and can grow on water pipes. Some actinomycetes produce a substance called geosmin, which gives off a musty, earthy smell and taste.
“Some levels are unacceptable, because it’s like we are drinking mud,” says Dr Ipek Kurtböke, a senior lecturer in environmental microbiology at USC.
The smell is especially common in places with older pipes, with cracks that can allow the bacteria to build up, and it can be very difficult to eradicate.
“Even if we remove [the bacteria] from the water system using chlorination, the diffuse smell stays,” says Kurtböke. Other chemical and physical treatments are needed to get rid of the smell, and they can become quite costly.
Kurtböke’s solution was to find a different enemy of bacteria: bacteriophages, or phages for short. These are viruses that evolved to infect bacteria – and fortunately, they don’t affect people.
“We use naturally occurring viruses,” summarises Kurtböke. “They are not harmful to people, and they only kill these bacteria.”
The researchers have shown in lab studies that their phages can get rid of actinomycetes before they produce too much of a musty smell. They can also choose phages that are target specific, so that they’re only destroying the noisome bacteria.
“If there are beneficial microorganisms in that environment, we have to use a narrow spectrum phage, so we do not kill other beneficial microbes,” says Kurtböke.
Next, the researchers are interested in testing their phages in industrial settings or council water treatment plants. This will take a fair bit of planning to set up, because the typical chlorination treatment kills the bacteria (but doesn’t remove the smell) – and if all the bacteria are dead, they can’t be infected or pass on any phages.
“We want to try this at a larger scale,” says Kurtböke.
Bacteriophages are not a newly discovered phenomenon. A number of former Soviet states, particularly Georgia, have been investigating phages since the 1930s, and they’ve drawn attention in recent years as potential solutions to antibiotic resistance.
“Georgia has been leading this for nearly 100 years, but because of antibiotics, nobody paid attention to the use of bacteriophages,” says Kurtböke.
“But now, because of antibiotic resistance, it’s coming back. It will be applied in clinical settings, in environmental settings, in food industry.”
In addition to the tapwater research, Kurtböke says their bacteriophage system can break up sea foam – and there are a number of other things they could be used for, too.
“We apply them all the time in many different settings, and we have 100% success in the laboratory.”