Since antimicrobial resistance is getting worse, scientists are constantly searching for novel substances.

This week, a group of multinational scientists working in Europe reported in the journal mBio that they have found a new antifungal antibiotic called solanimycin.

The chemical, first identified from a potato-infecting pathogen, appears to be generated by related plant pathogens.

The researchers found that solanimycin inhibits a variety of fungus known to damage and infect agricultural crops.

In lab experiments, the compound was also effective against Candida albicans, a naturally occurring fungus that can cause serious infections.

The findings imply that solanimycin and related drugs may be helpful in both clinical and agricultural situations.

Most of the antibiotics used in medicine today are produced by soil microbes, particularly those belonging to the phylum Actinobacteria. According to scientist Rita Monson, Ph.D., of the University of Cambridge, the new finding shows that plant-based microorganisms are worth further investigation, particularly as crops grow resistant to current treatments. She co-led the investigation with molecular microbiologist Miguel Matilla, Ph.D., at the Estación Experimental del Zaidn of the Spanish Research Council in Granada.

Monson said, “We have to look more expansively across much more of the microbial populations available to us.”

More than 15 years ago, the pathogenic potato bacteria Dickeya solani was identified. About ten years ago, scientists in molecular microbiologist George Salmond’s group at the University of Cambridge started looking into the substance’s antibiotic potential.

According to Matilla, “These strains emerged rapidly, and now they are widely distributed.”

Solanimycin is not the first antibiotic that scientists have found in a microbe. In earlier research, scientists discovered that D. solani generates the antibiotic oocydin A, which is very effective against a variety of fungal plant infections.

These earlier findings suggested that the bacterium might produce other antibiotics with the potential to be antifungal, according to Matilla, who also analyzed the genome of the organism. That tip paid off: Matilla, Monson, Salmond and their colleagues discovered that the bacteria continued to exhibit antifungal activity even after silencing the genes essential for the production of oocydin A.

This led to the discovery of solanimycin and the finding of the clusters of genes that make the proteins that make the compound.

Scientists discovered that the bacterium produces the substance in response to cell density and uses it sparingly. The solanimycin gene cluster is also activated in an acidic pH environment, like the one found in potatoes. It almost seems like a clever protection system, according to Monson.

The antifungal, according to Monson, “will work by killing fungal competitors, and the bacteria benefit so much from this. But you don’t turn it on unless you’re in a potato” .

Monson said that scientists have began working with chemists to better understand the molecular structure and mechanism of solanimycin. They hope for more research on the substance using plant and animal models.

“Our future steps are focused on trying to use this antibiotic antifungal for plant protection,” Matilla added. 

They are optimistic that plant pathogens like D. solani can be induced to produce chemicals that can be used to treat plant and human ailments.

“We have to open to the exploration of everything that’s out there to find new antibiotics,” Matilla added.

Source: 10.1128/mbio.02472-22

Image Credit: Getty

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