Antimicrobial resistance is a global health challenge, leading researchers to search for new compounds everywhere. Now, a multinational team of researchers in Europe has discovered a new antifungal antibiotic. The compound was initially isolated from a pathogenic bacterium that infects potatoes, and is produced by a broad spectrum of related plant pathogenic bacteria. The new antifungal antibiotic produced by some plant pathogenic bacteria is called solanimycin. The findings, led by researchers from the American Society for Microbiology, were recently published in the journal mBio.
What is solanimycin?
Solanimycin is an antibiotic that acts against a wide range of fungi known to infect and wreak havoc on agricultural crops, the authors noted in the study. During lab studies, the researchers observed that the compound acted against Candida albicans, a fungus that occurs naturally in the body but can cause dangerous infections.
The findings suggest that solanimycin and related compounds could be useful in both agricultural and clinical settings.
Soil microbes, especially those belonging to the Actinobacteria phylum, produce most therapeutic antibiotics used today. Plant-based microorganisms are worth a closer look, especially because crops develop a resistance to existing treatments, Rita Monson, one of the lead authors on the paper, said in a statement released by the American Society for Microbiology.
She also said that researchers have to look more expansively across much more of the microbial populations available to them.
What is the bacterium that produces the antifungal antibiotic?
The pathogenic potato bacterium is called Dickeyasolani. It was first identified more than 15 years ago.
About a decade ago, researchers in the lab of molecular microbiologist George Salmond from the University of Cambridge began investigating the antibiotic potential of Dickeyasolani.
Molecular microbiologist Miguel Matilla, one of the lead authors on the paper, said the strains emerged rapidly, and now, they are widely distributed.
The potato pathogenic bacterium synthesises additional antibiotics
According to the study, solanimycin is not the first antibiotic discovered from the pathogenic microbe Dickeyasolani. Researchers had earlier found that Dickeyasolani produces an antibiotic called oocydin A, which is highly active against multiple fungal plant pathogens.
Matilla said that the previous discoveries, together with the analysis of the genome of the bacterium, hinted that it may synthesise additional antibiotics, also with antifungal potential.
How solanimycin works
The hint paid off because Matilla, Monson, Salmond and their colleagues found that when they silenced the genes responsible for the production of oocydin A, the bacterium continued to show antifungal activity.
In this way, the researchers identified solanimycin and gene clusters responsible for the proteins that make the compound.
The study found that the pathogenic bacterium uses the compound sparingly, and produces it in response to cell density. According to the study, an acidic pH environment, which is found in potatoes, also activates the solanimycin gene cluster, something Monson calls a “clever protective mechanism”.
She further said that it is an antifungal the team believes will work by killing competitors. The bacteria benefit a lot from the antifungal antibiotic.
What’s next?
Next, the researchers aim to understand the molecular structure of solanimycin and know how it works, in order to produce compounds that can offer protection against diseases in plants and people.