The mucus of the garden snail, Cornu aspersum, contains proteins with antibacterial potential, a new study finds.
Who would think of looking to the humble garden snail for a solution to antibiotic resistance, the phenomenon of harmful bacteria becoming unresponsive to drugs that could previously defeat them?
As it turns out, two researchers from the United Kingdom, who also happen to be husband and wife.
They are Sarah Pitt, Ph.D., principal lecturer in the School of Pharmacy and Biomolecular Science at the University of Brighton, and Alan Gunn, Ph.D., subject lead for biosciences in the School of Natural Sciences and Psychology at Liverpool John Moores University.
According to Pitt, the idea just occurred to her husband, who expressed curiosity about the resilience of garden snails: “He was idly wondering about snails moving over the soil, etc., in a garden which is full of bacteria and how/why they appear to stay healthy. Was there something in the mucus which fought against infections?”
This snail mucus soon became the subject of an undergraduate student project that Gunn coordinated to investigate whether any components of the mucus might have antimicrobial properties.
However, as Gunn started discussing his laboratory methods with Pitt, she noted that his procedures were not likely to be successful.
“He thought something interesting might be happening, but when I discussed his lab methods, it was clear he was doing it all wrong. So, I did what wives tend to do and said ‘you are doing that all wrong — give it to me, and I’ll sort it out’ — which I did.”
Sarah Pitt, Ph.D.
After Pitt took over the investigation, the researchers’ study yielded some surprising results — they discovered four previously unknown proteins in the snail mucus.
Moreover, two of these proteins proved to have strong antimicrobial properties, particularly against aggressive strains of Pseudomonas aeruginosa, a bacterium that causes dangerous lung infections in people with cystic fibrosis.
The antibacterial potential of snail mucus
In their study, the results of which now appear in the British Journal of Biomedical Science, the researchers collected mucus from common garden snails (Cornu aspersum) and found that it was able to inhibit various strains of P. aeruginosa that had come from individuals with cystic fibrosis-related infections.
“In previous work, we found that the mucus consistently and convincingly inhibited the growth of one species of bacterium P. aeruginosa, a tough bacterium that can cause disease, but it did not seem to work against other bacteria,” says Pitt.
“So, in this study,” she continues, “we tried all the control strains of P. aeruginosa we had available in the lab here at the university as well as five strains taken from patients with [cystic fibrosis] who had lung infections with this bacterium.”
Pitt collaborated with researchers from King’s College London, U.K., to separate proteins from the snail mucus and then test each of them, controlling for antibacterial properties.
As a result, the investigators identified no fewer than four previously unknown proteins, of which three appeared to be effective against different bacterial strains. One of them, “the 37.4 kDa protein, to be named Aspernin,” the study paper explains, has strong antimicrobial properties and a lot of therapeutic potential.
Another two of the new proteins, which the team labeled “17.5 kDa” and “18.6 kDa,” are apparently able to attack infection-causing P. aeruginosa, in particular.
“P. aeruginosa is a very important cause of lung infections in patients with [cystic fibrosis], and strains which are resistant to the most commonly used antibiotic treatments are becoming increasingly common,” Pitt emphasizes, noting that for this reason, “a new antibiotic would be useful.”
The current discoveries open up new possibilities for therapeutic approaches, and the researchers are hopeful that, in the future, they may be able to work the proteins with healing potential into novel treatments.
“If we can make the proteins artificially in the lab, we can try and work out what they are doing to the bacterium. We think that it might be possible to incorporate the purified protein into a cream to treat deep burn wounds and possibly an aerosol to treat lung infections,” says Pitt.