A research team is working to understand how bacteria use viruses to eliminate their competition, which could help in finding alternatives to antibiotics. Bacteriophages, viruses that target and destroy bacteria, are found throughout nature and play a crucial role in controlling microbe populations, although the details of this process are still not fully understood. A recent study from the University of Utah and University College London (UCL) discovered that plant bacterial pathogens are able to utilize parts of their own bacteriophages to eliminate competitors.The discovery of phages in microbial pathogens was unexpected and could potentially provide an alternative to antibiotics, according to Talia Karasov, an assistant professor in the U’s School of Biological Sciences.
Karasov and an international team of scientists were surprised by the findings of their research.
Karasov’s research focuses on the interactions between plants and microbial pathogens, and she notes that while microbial pathogens are abundant, they do not always cause illness in humans, animals, or plants. The Karasov lab is working to uncover the factors that contribute to this.The study focused on the contrast between the spread of pathogens leading to illness and outbreaks, and the containment of these pathogens. The lab’s previous research examined the behavior of a specific bacterial pathogen, Pseudomonas viridiflava, in both agricultural and natural settings. They discovered that one variant of the pathogen would widely propagate in a cultivated crop field, becoming the predominant microbe. However, this did not occur in uncultivated land, prompting further investigation by Karasov and the team. Their findings revealed that no single lineage of bacteria could dominate in the uncultivated land, leading them to question whether the phages, or pathogens of the bacterial pathogens, could be preventing the dominance of single lineages. Perhaps the phages were the reason behind the prevention.”Our study initially focused on identifying which phages were infecting plant bacterial pathogens, but we discovered something unexpected,” stated Karasov. “Instead of simply identifying the phages, we found that the bacteria had repurposed them for warfare against other bacteria, using them to eliminate competing bacteria.” The research, published in Science, revealed that the pathogen acquires non-self-replicating clusters of repurposed phage, known as tailocins, which are used to penetrate the outer membranes of other pathogens.Rewrite:
“Ill them. After finding this continuous battle in the bacterial pathogen populations, the Karasov lab and Hernán Burbano’s lab at UCL examined the genomes of modern and historical pathogens to understand how the bacteria change to target each other.
“You can picture a constant struggle between the bacteria as they attempt to eliminate each other and develop resistance to one another over time,” Burbano explained. “The herbarium samples from the past 200 years that we studied offered a glimpse into this struggle, revealing how bacteria avoid being killed by their rivals.”
Mining herbarium specimens for their microbial DNA
Burbano has been at the forefront of using herbarium specimens to study the evolution of plants and their microbial pathogens. In his lab, the genomes of both the host plants and the associated microbes from over a century ago are sequenced.
For the phage research, Burbano examined historical specimens of Arabidopsis thaliana, a plant from the mustard family also known as thale cress, collected in southwestern Germany. He compared these specimens and the microbes they contained to the plants growing in the same area today.
Germany was the location of the historical tailocins that were found in the present-day dataset, indicating that evolution has preserved the diversity of tailocin variants over the past century,” said the researcher. “This suggests a limited number of possible resistance/sensitivity mechanisms within the bacterial population we studied.
Talia Backman, the lead author, wonders if tailocins could be a solution to the growing problem of antibiotic resistance in harmful bacteria that infect humans.
“Our society is in urgent need of new antibiotics, and tailocins have the potential to be new antimicrobial agents,” she said.
Tailocins are an interesting area of study, according to Backman, a graduate student in the Karasov lab. While tailocins have been discovered in other bacterial genomes and have been researched in laboratory settings, their impact and evolution in wild bacterial populations was previously unknown. The discovery that these wild plant pathogens all possess tailocins, and that these tailocins are evolving to destroy neighboring bacteria, demonstrates their potential significance in nature.”
Similar to most pesticides, many of our antibiotics were created years ago to eradicate a wide range of harmful organisms, including those that are detrimental and beneficial to human and plant health. On the other hand, tailocinsOn the other hand, tailocins are more specific than many modern antibiotics, as they only target a small number of bacteria strains. This suggests that they could be used without causing harm to entire biological communities.
According to Karasov, this is currently basic research and not ready for practical use. However, there is potential for adapting tailocins to treat infections. He also pointed out that society typically uses broad-spectrum treatments for pests in agriculture and bacterial pathogens in humans. The specificity of tailocin killing could lead to more tailored treatments in the future.
The study is titled “A recent study published in the June 14 edition of Science found that a phage tail-like bacteriocin is able to suppress competitors in metapopulations of pathogenic bacteria. The research was funded by the National Institutes of Health, University of Utah startup funds, the Leverhulme Trust, and the Royal Society. The U School of Biological Sciences collaborated with University College London, the Max Planck Institute for Biology, the Complex Carbohydrate Research Center Analytical Services and Training Lab at the University of Georgia, New York University, the U’s Department of Biochemistry, and Lawrence Berkeley National Laboratory.
