The potato is the vegetable of choice in the United States. On average, Americans devour about 65 kg of them per year. Credit: Scott Bauer, USDA ARS
Key Points:
- Researchers have discovered solanimycin, a new antifungal antibiotic produced by a range of plant pathogenic bacteria.
- The team is working with chemists to learn more about the molecular structure of solanimycin and better understand how it works.
- Plant-associated bacteria are a potential source of antibiotics that could be used clinically and agronomically.
The growing threat of antibiotic resistance has scientists looking high and low for alternatives. Recently, a multinational team of researchers in Europe found their answer by looking down—in the soil.
As reported in mBio, the researchers discovered a new antifungal antibiotic named solanimycin. The compound, initially isolated from a pathogenic bacterium that infects potatoes, appears to be produced by a broad spectrum of related plant pathogenic bacteria.
Solanimycin isn’t the first antibiotic discovered from associated soil microbes. In previous work, researchers found that Dickeya solani—the pathogenetic potato bacterium—produces an antibiotic called oocydin A, which is highly active against multiple fungal plant pathogens.
Those previous discoveries, together with the analysis of the genome of the bacterium, hinted that it might synthesize additional antibiotics. With that in mind, microbiologists Miguel Matilla, Rita Monson, George Salmond and colleagues discovered that when they silenced the genes responsible for the production of oocydin A, the bacterium continued to show antifungal activity. That observation led to the identification of solanimycin and the identification of the gene clusters responsible for the proteins that make the compound.
The researchers found that the bacterium uses the compound sparingly, producing it in response to cell density. An acidic pH environment—as that present in a potato—also activates the solanimycin gene cluster.
“It’s an antifungal that we believe that will work by killing fungal competitors, and the bacteria benefit so much from this,” said Monson, a professor at the University of Cambridge. “But you don’t turn it on unless you’re in a potato.”
Monson said the researchers have begun collaborating with chemists to learn more about the molecular structure of solanimycin and better understand how it works.
“Our future steps are focused on trying to use this antibiotic antifungal for plant protection,” said Matilla, a researcher at the Spanish Research Council’s Estación Experimental del Zaidín.
The research team sees the discovery as an encouraging sign that plant pathogens—like D. solani—could be coaxed to make compounds that may be used against diseases in plants and people.
“We have to open to the exploration of everything that’s out there to find new antibiotics,” said Matilla.
Information provided by American Society for Microbiology.