Dangerous bacterium discovered in potato produces new antibiotics

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New finding shows plant-based microbes deserve further investigation, especially as crops become resistant to current treatments





Antimicrobial resistance is increasingly becoming a problem, so researchers everywhere are looking for new substances. This week in mBio, a global research team in Europe reports the discovery of the new antifungal antibiotic solanimycin.












The chemical, which was discovered from a pathogenic bacterium that infects potatoes, appears to be produced by a diverse group of closely related plant pathogenic bacteria. Solanimycin, the researchers found, inhibits a wide range of fungi known to harm and infect agricultural crops. The substance also inhibited the growth of Candida albicans, a fungus that normally lives in the body but can cause potentially dangerous infections, in lab tests. The results suggest that solanimycin and related drugs may be beneficial in clinical and agricultural settings.

Antimicrobial resistance is increasingly becoming a problem, so researchers everywhere are looking for new substances. The majority of antibiotics used today are produced by soil microorganisms, particularly those of the Actinobacteria phylum. According to University of Cambridge scientist Rita Monson, PhD, the new finding shows that plant-derived microbes deserve further investigation, especially as crops become resistant to current treatments.

She co-led the study with molecular microbiologist Miguel Matilla, PhD, at the Spanish Research Council’s Estacion Experimental del Zaidn in Granada. “We need to more broadly investigate many more microbial populations available to us,” Monson said. Dickeya solani, a potato pathogen discovered more than 15 years ago, produces solanimycin. Scientists from molecular microbiologist George Salmond’s group at the University of Cambridge began studying the substance’s antibiotic potential about a decade ago.












“These strains evolved rapidly and are now widely available,” says Matilla. Solanimycin is not the first antibiotic derived from bacteria. Previously, scientists had found that D. solani produced the antibiotic oocydin A, which is extremely effective against a wide range of plant fungal infections. According to Matilla, who also examined the organism’s genome, previous findings suggested that the bacterium could produce other antibiotics with antifungal properties.

This trick paid off: Matilla, Monson, Salmond and their colleagues discovered that the bacterium retained antifungal activity even after silencing the genes necessary for the production of oocydin A. As a result of this observation, the chemical solanimycin and the gene clusters responsible for the proteins that produce it have been discovered. The bacterium produces the chemical in response to cell density and uses it sparingly, the researchers said.

An acidic pH environment, such as that found in potatoes, also activates the solanimycin gene cluster. According to Monson, it almost feels like an intelligent protection system. According to Monson, the antifungal “will work by destroying fungal competitors, and the bacteria will benefit greatly.” You can’t light it unless you’re inside a potato. Scientists began working with chemists, according to Monson, to better understand the molecular makeup of solanimycin and how it works. She went on to say that she and Matilla hoped more research on the substance would be conducted using plant and animal models.












According to Matilla, the next step will be to try to use this antifungal antibiotic for plant protection. The study results are interpreted as a positive sign that plant pathogens like D. solani can be encouraged to produce chemicals that can be used to treat plant and human diseases.

(Source: American Society for Microbiology)











First published: October 11, 2022, 11:08 IST


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