Potato Review

www.potatoreview.com POTATO REVIEW NOVEMBER/DECEMBER 2022 15 NEWS AN international team of researchers has discovered a new antibiotic in bacteria that infects potatoes. The team of researchers in Europe reported discovering 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. It acts against fungi known to infect and wreak havoc on crops, according to the researchers. In lab studies, it also acted against Candida albicans, a fungus that occurs naturally in the body but can cause dangerous infections. Results suggest solanimycin and related compounds could be used in agricultural and clinical settings. Soil microbes, especially from the Actinobacteria phylum, produce most therapeutic antibiotics used today. The new discovery suggests plant- based microorganisms are worth a closer look, especially as crops develop resistance to existing treatments. Microbiologist Rita Monson, Ph.D., at the University of Cambridge, co-led the study with molecular microbiologist Miguel Matilla, Ph.D., at the Spanish Research Council’s Estación Experimental del Zaidín, in Granada. The pathogenic potato bacterium Dickeya solani, which produces solanimycin, was first identified more than 15 years ago. Researchers in the lab of molecular microbiologist George Salmond, Ph.D., at the University of Cambridge, began investigating its antibiotic potential about a decade ago. Miguel Matilla said: “These strains emerged rapidly, and now they are widely distributed.” In previous work, researchers found that D. solani produces an antibiotic called oocydin A, which is highly active against multiple fungal plant pathogens. Those discoveries, together with the analysis of the genome of the bacterium, hinted that it might synthesize additional antibiotics. The team found that when they silenced the genes responsible for the production of oocydin A, the bacterium continued to show antifungal activity. This 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 such as that found in potato also activates the solanimycin gene cluster. Rita said it almost looks like a clever protective mechanism. “It’s an antifungal that we believe will work by killing fungal competitors, and the bacteria benefit so much from this,” she said. “But you don’t turn it on unless you’re in a potato.” The researchers have begun collaborating with chemists to learn more about the molecular structure of solanimycin and to better understand how it works. They hope to see continued testing of the compound in plant and animal models. New antibiotic in diseased potatoes thwarts fungal infections in plants and humans. Bacteria’s friend could save lives “It’s an antifungal that we believe 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.”