Antibiotic found in potato disease thwarts fungal infections

Antibiotic resistance is a worry for human and plant health alike. The more we use existing antibiotics in clinical settings and in agriculture, the more antibiotic resistance develops. Without new antibiotic compounds, we will struggle to treat once-controlled diseases in both humans and plants.

Exciting new research from Europe details the discovery of a new antifungal antibiotic called solanimycin hiding within a bacteria which causes disease in potatoes.

Most therapeutic antibiotics actually come from soil microbes, so this discovery broadens the search for new compounds to plant-based microorganisms.

“We have to look more expansively across much more of the microbial populations available to us,” said Dr. Rita Monson a microbiologist at the University of Cambridge and one of the study’s authors.

Blackleg in potatoes one of the symptoms of Dickeya solani. Credit: Liudmyla Liudmyla/Getty Images

The bacteria itself, known as Dickeya solani, has been known for over 15 years, with another antibiotic called oocydin A originally isolated from the bacteria and used as an effective fungicide against many plant ailments.

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From this, and a sequencing of the bacterium’s genome, the researchers realised the potential for other antibiotic compounds to be hiding in the background. When they switched off the genes responsible for producing oocydin A and when the bacteria were within an acidic background – such as that found inside a potato – it would switch on genes responsible for creating solanimycin.

“It’s an antifungal that we believe that will work by killing fungal competitors, and the bacteria benefit so much from this,” said Monson. “But you don’t turn it on unless you’re in a potato.”

Antiobiotic resistance: an arms race going on millions of years

Computer illustration of Candida fungi (yeast). C. albicans is found on the skin and mucous membranes of the mouth, genitals, respiratory and digestive tracts. Credit: Kateryna Koc/Science Photo/Library/Getty Images

Solanimycin has been demonstrated to act against fungal disease in both plants and also on a common organism known as Candida albicans, which is present inside the body naturally, but can become out of control and cause dangerous infections.

Monson and colleagues want to understand more about solanimycin and how it works, so they have teamed up with chemists to investigate the molecular structure in detail. From there, they hope to progress to testing the compound in plant and animal models.