Helper bacteria protect button mushrooms from disease by enzymatically disarming toxins and disabling pathogens' motility, according to a study. The bacterial pathogen Pseudomonas tolaasii causes brown blotch disease in white button mushrooms, an important food source. Helper bacterial strains Mycetocola tolaasinivorans and Mycetocola lacteus appear to protect the mushrooms from the tolaasin toxin, but the underlying mechanism is unclear. Christian Hertweck and colleagues report that helper bacteria defend mushrooms against the pathogen by enzymatically disabling the toxin as well as the pathogen's motility. When the authors grew the helper bacteria together with the pathogen, they found that toxin production was reduced and the pathogen's ability to swarm was hampered. Two different molecules with a ring-like chemical structure confer motility and toxicity on P. tolaasii. The authors isolated one of the enzymes underlying the helper bacteria's protective action by analyzing fractions of Mycetocola cell lysate. Next, the authors analyzed the specificity of the enzyme, a lactonase, and found that it neutralizes tolaasin through lipopeptide cleavage, snipping the ring-shaped peptide into a linear structure. According to the authors, understanding how helper bacteria prevent infection in important agricultural species could help develop biocontrol strains for use in food production as well as medicine.
Article #20-06109: "Helper bacteria halt and disarm mushroom pathogens by linearizing structurally diverse cyclolipopeptides," by Ron Hermenau, Susann Kugel, Anna J. Komor, and Christian Hertweck.
MEDIA CONTACT: Christian Hertweck, Leibniz Institute for Natural Product Research and Infection Biology (HKI) and Friedrich Schiller University Jena, GERMANY; e-mail: christian.hertweck@leibniz-hki.de
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Proceedings of the National Academy of Sciences