In the heart of Barcelona, a team of researchers led by Gloria Vique from the University of Barcelona’s Department of Genetics, Microbiology, and Statistics has made a significant stride in the fight against two notorious plant pathogens. Their work, published in the journal Microbiology Spectrum (translated as Microbiology Spectrum), explores the use of bacteriophages—viruses that infect bacteria—as a sustainable and effective method to control fire blight and black rot, diseases that cause substantial economic losses in agriculture.
The study focuses on two phytopathogens: Erwinia amylovora, which causes fire blight in apples and pears, and Xanthomonas campestris pv. campestris, responsible for black rot in cruciferous vegetables like kohlrabi. Traditional chemical pesticides, while effective, often come with a hefty environmental price tag. They can harm soil fertility, contaminate water sources, and impact non-target organisms such as natural predators and pollinators. This has sparked a global search for more sustainable pest control methods, and bacteriophages are emerging as a promising alternative.
Vique and her team isolated three virulent phages from urban wastewater: ɸEF1 and ɸEF2, which target E. amylovora, and ɸXF1, which targets X. campestris pv. campestris. Genetic analysis confirmed the absence of known lysogeny-related genes, meaning these phages do not integrate into the bacterial genome and instead lyse, or burst, the bacterial cells. This makes them ideal candidates for biocontrol applications.
In vitro assays demonstrated significant bacterial population reductions. “We were thrilled to see that ɸEF1 killed 92.1% of the E. amylovora population at a multiplicity of infection (MOI) of 1 after just 3 hours,” Vique explains. “But when we combined ɸEF1 and ɸEF2 in a 1:1 ratio, the reduction was even more dramatic—99.7%—with no regrowth of resistant cells.” This is a crucial finding, as the development of resistant bacterial strains can often hinder the effectiveness of single-phage treatments.
The team also tested the phages in vivo using pears and kohlrabi as infection models. The results were equally promising. Treated pears showed reduced fire blight symptoms, and kohlrabi plants exhibited markedly less necrosis from black rot compared to untreated controls. “These findings highlight the potential of these phages as biocontrol agents for managing bacterial plant diseases,” Vique says. “They offer an alternative to traditional chemical treatments, which can have harmful environmental impacts.”
The commercial implications of this research are substantial. The global market for agricultural biocontrol agents is projected to grow significantly in the coming years, driven by increasing demand for sustainable and eco-friendly solutions. Phage-based biocontrol agents could play a pivotal role in this market, offering farmers an effective and environmentally friendly way to protect their crops.
Moreover, the use of phage cocktails—combinations of multiple phages—could help prevent the development of resistant bacterial strains, ensuring the long-term effectiveness of these treatments. This could be particularly beneficial in the energy sector, where crops are often grown for biofuel production. By protecting these crops from disease, phage-based biocontrol agents could help ensure a steady supply of feedstock for biofuel production, contributing to a more sustainable energy future.
This research is a significant step forward in the field of agricultural biocontrol. As Vique and her team continue to explore the potential of bacteriophages, they are paving the way for a more sustainable and productive future for agriculture. Their work, published in Microbiology Spectrum, serves as a testament to the power of innovative research in addressing global challenges.