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Rediscovery of viomellein as an antibacterial compound and identification of its biosynthetic gene cluster in dermatophytes

Summary

Researchers discovered that dermatophytes, fungi that cause common skin infections like athlete’s foot, produce a red pigment called viomellein that kills bacteria. By studying the genes responsible for making this compound, scientists found that most dermatophytes produce it, which may help explain how these fungi establish infections on skin despite the presence of protective bacteria. This discovery opens new possibilities for understanding skin infections and potentially developing new treatments.

Background

Dermatophytes are widespread human pathogens affecting over one billion people worldwide, but their mechanisms of infection remain poorly understood. While bacterial density at infection sites is abundant, interactions between dermatophytes and bacterial communities have been understudied. Recent advances in genomics and metabolomics provide opportunities to investigate antimicrobial substances produced by dermatophytes.

Objective

To identify antibacterial compounds produced by Trichophyton rubrum and other dermatophytes and characterize their biosynthetic gene clusters. The study aimed to understand how dermatophytes interact with skin microbiota during infection and identify previously unknown molecular entities involved in this process.

Results

Viomellein was identified as a potent antibacterial pigment with MIC of 0.78 µg/mL against Staphylococcus aureus. The vio biosynthetic gene cluster was characterized, revealing a pathway producing viomellein via nor-toralactone, semivioxanthin, and vioxanthin. The cluster is conserved across most dermatophyte species and present in some Aspergillus and Penicillium species, with most dermatophytes producing multiple naphthopyranone compounds.

Conclusion

Dermatophytes produce diverse naphthopyranone compounds with strong antibacterial activity that may represent an initial infection strategy. The genetic and chemical characterization of viomellein biosynthesis provides insights into dermatophyte-microbiota interactions and opens new avenues for understanding infection ecology and potential therapeutic targets.
  • Published in:Applied and Environmental Microbiology,
  • Study Type:Experimental Research,
  • Source: PMID: 40197033
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