The Antimicrobial Compound Xantholysin Defines a New Group of Pseudomonas Cyclic Lipopeptides

Summary

This research discovered a new antibiotic compound called xantholysin produced by soil bacteria. The compound has unique properties that allow it to kill both harmful bacteria and fungi, making it potentially useful for protecting plants from diseases. The study reveals how bacteria can evolve to produce new antibiotic compounds by mixing and matching different genetic building blocks. Impacts on everyday life: – Could lead to new agricultural treatments to protect crops from bacterial and fungal diseases – Demonstrates nature’s ability to produce new antibiotics, important for fighting drug resistance – Provides insights for developing new antimicrobial compounds through biotechnology – May help improve our understanding of how beneficial soil bacteria protect plants – Could inspire new approaches for controlling harmful bacteria in various settings

Background

Certain soil-dwelling and plant-associated bacteria display highly versatile secondary metabolism and are valuable sources for structurally diverse metabolites with useful biological activities, including antibiotics. While Streptomyces and other actinomycetes are major producers of clinical antibiotics, several antimicrobials from other soil bacteria like Bacillus and Pseudomonas contribute to their capacity to suppress fungal plant diseases.

Objective

To characterize the novel antimicrobial compound xantholysin produced by Pseudomonas putida BW11M1, a strain isolated from banana rhizosphere, and determine its biosynthetic pathway and biological activities.

Results

The study identified xantholysin as a novel cyclic lipotetradecapeptide produced by three co-linearly operating non-ribosomal peptide synthetases (XtlA, XtlB, XtlC). The compound showed antimicrobial activity against several Xanthomonas species, some other Gram-negative bacteria, most tested Gram-positive bacteria, and various fungi. Two minor structural variants (xantholysin B and C) were also characterized. Xantholysin was found to be required for swarming motility and contributed to biofilm formation.

Conclusion

Xantholysin represents a new group of Pseudomonas lipopeptides with unusual broad-spectrum antimicrobial activity, including against Gram-negative bacteria. The biosynthetic system shows similarity to other Pseudomonas lipopeptide synthetases but produces structurally distinct compounds, suggesting bacteria can recruit and reshuffle individual biosynthetic units to engineer novel assembly lines for diversified lipopeptide synthesis.
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