UCL Faculty of Life Sciences


UCL-led research unveils bacteriophages repurposed by plant pathogens to combat microbial rivals

13 June 2024

Bacteriophages, viruses that attack and destroy bacteria, are everywhere in the natural world, playing a vital yet not fully understood role in regulating microbe populations.

A phage-tail-like bacteriocin targets and kills neighboring non-self bacteria

New research led by UCL and the University of Utah has discovered that plant bacterial pathogens can repurpose elements of their own bacteriophages, or phages, to eliminate competing microbes. These surprising findings suggest that such phage-derived elements could one day be used as an alternative to antibiotics, according to co-senior author, Hernán A. Burbano, an Associate Professor of Ancient Plant Genomics and Royal Society Wolfson Fellow in the Division of Biosciences. 

This outcome was unexpected when the research team, including an international group of scientists, began their study. While investigating the factors that shape the genetic diversity of bacterial pathogens over time, the team uncovered the role that phage-derived elements play in the competition among different yet closely related bacterial pathogenic strains.

According to the study published in Science, the pathogen acquires elements of the phages as non-self-replicating clusters called tailocins, which penetrate and kill other pathogens. After uncovering this bacterial warfare, Burbano's lab, along with the Karasov lab at the University of Utah, analysed modern and historical pathogen genomes to understand how bacteria evolve to target each other.

Burbano has pioneered the use of herbarium specimens to study the evolution of plants and their microbial pathogens. His lab sequences the genomes of both host plants and associated microbes from collections dating back more than a century. For this research, Burbano analysed historical specimens of Arabidopsis thaliana, a mustard family plant, from southwestern Germany and compared them with modern specimens from the same region.

“We found that all historical tailocins were present in our current dataset, suggesting that the diversity of tailocin variants has been maintained over a century,” he noted. “This likely indicates a finite set of possible resistance and sensitivity mechanisms within the studied bacterial population.”

First-author Talia Backman posits that tailocins might address the growing antibiotic resistance crisis in harmful bacteria that infect humans. "We urgently need new antibiotics, and tailocins have potential as new antimicrobial treatments,” said Backman, a graduate student in the Karasov lab. “While tailocins have been found in other bacterial genomes and studied in lab settings, their impact and evolution in wild bacterial populations were unknown. Our findings show that these wild plant pathogens all have tailocins, which rapidly evolve to kill neighboring bacteria, highlighting their significance in nature.”

“This is basic research at this point, not yet ready for application, but I think that there is good potential that this could be adapted for treating infection,” said Professor Talia Karasov. She added: “We as a society have, in how we treat both pests in agriculture and bacterial pathogens in humans, used uniform and broad-spectrum treatments. The specificity of tailocin killing is a way that you could imagine doing more finely tailored treatments.”

Unlike many pesticides and antibiotics developed decades ago to kill a broad array of organisms, bacteriophages have greater specificity, targeting only select bacterial strains. This suggests they could be used without disrupting entire biological communities.

The study, titled “A phage tail–like bacteriocin suppresses competitors in metapopulations of pathogenic bacteria,” was published in the 14th June edition of Science. 

The research was supported by the National Institutes of Health, University of Utah startup funds, the Leverhulme Trust, and the Royal Society. 

Collaborating institutions included University College London, the Max Planck Institute for Biology, the Complex Carbohydrate Research Center at the University of Georgia, New York University, the University of Utah's Department of Biochemistry, and Lawrence Berkeley National Laboratory.

Image caption:

A phage-tail-like bacteriocin targets and kills neighboring non-self bacteria.

Image credit:

Courtesy of Daniel Rouhani.

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