Keanu Reeves, The Molecule: New Active Ingredient From Bacteria Could Protect Plants

By Ronja Münch, Leibniz Institute for Natural Products and Infection Biology

Researchers at Leibniz Natural Products Research and Infection Biology (Leibniz-HK) found that bacteria from the genus Pseudomonas produce powerful antimicrobial natural products. They found that the substance was effective against plant fungal diseases and fungi pathogenic to humans. The research is published in the Journal of the American Chemical Society and is discussed in an editorial in Nature .

Keanomycins, a group of natural products recently discovered on bacteria, are effective against the pest Botrytis cinerea, which causes gray mold and significant annual yield loss. However, the active ingredients prevent the appearance of harmful fungi for humans, such as Candida albicans. Previous studies have shown it is harmless to plants and human cells.

Therefore, keanomycin can be an environmentally friendly alternative to chemical pesticides, but it can also be an alternative for controlling resistant fungi. "We have a problem with anti-inflammatory drugs," said Sebastian Götz, first author of the study and postdoctoral researcher at Leibniz-HK. "Many fungi pathogenic to humans are now resistant to antifungal drugs, in part because they are widely used in agriculture."

A killer like John Wick

It is no coincidence that researchers discovered a new active principle in the bacteria of the genus Pseudomonas. "We have been working with pseudomonads for some time and we know that many of these types of bacteria are highly toxic to the amoebas that feed on them," said study leader Pierre Stalfort. He is head of the Department of Paleotechnology at Leibniz-HKI and Professor of Bioorganic Chemistry and Paleotechnology at Friedrich Schiller University Jena.

Several poisons are responsible for the lethal effect of bacteria, one of which is still unknown. The researchers found genes for the biosynthesis of the newly discovered natural substances kenomycin A, B and C in the bacterial genome.

Together with colleagues from Leibniz-HK Biotechnikum, the researchers were able to identify one of the keanomycins and carry out further studies. "Lipopeptides are so good at killing that we named them after Keanu Reeves because he is the deadliest in his field," explained Goetz with a wink.

Researchers suspect that cyanomycin may kill the fungus because it resembles an amoeba in several ways. This hypothesis was confirmed by the Center for Horticultural Research at the University of Erfurt. Keanomycin was found there to be effective against gray mold that rots hydrangea leaves. In this case, the culture liquid that does not contain bacterial cells is sufficient to significantly inhibit the growth of the fungus.

"Theoretically, the supernatant from Pseudomonas cultures containing keanomycin can be used directly for plants," says Götze. Further tests were carried out with colleagues in Erfurt. Keanomycin is biodegradable, so no permanent residue forms in soil. This means that natural products can be an environmentally friendly alternative to chemical pesticides.

Fungal diseases such as Botrytis cinerea, which causes gray rot, cause enormous crop losses in horticulture and vegetables each year. More than 200 types of fruit and vegetables are affected, including unripe strawberries and grapes.

Possible human applications

“We also tested the isolated substances against various fungi that attack humans. We found that it strongly inhibited the fungal pathogen Candida albicans and others," said Goetz.

Keanomycin can be used in humans as a plant substitute. According to preliminary tests, the natural product has low toxicity to human cells and is effective against fungi even in very small doses. This makes it a good candidate for the development of new antifungal drugs. There are very few antifungal drugs on the market, and they are urgently needed.

Further information: Sebastian Goetze et al., Ecological Niche-Induced Genome Mining Leads to Discovery of Non-Plant Defense Lipopeptides as Building Blocks of Transient Amino Acids, Journal of the American Chemical Society (2023). DOI: 10.1021/jacs.2c11107

Andrew Mitchinson, Predicted bacterial defenses against bronchitis, Nature (2023). DOI: 10.1038/d41586-023-00195-x

Presented by the Leibniz Institute for Natural Products and Infection Biology

Excerpt: Keanu Reeves, Molecules: New bacterial materials can protect plants (6 February 2023) Accessed 6 February 2023, from https://phys.org/news/2023-02-keanu-reeves-molecule-ingredient-bacteria HTML

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