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Fruiting body-associated Pseudomonas contact triggers ROS-mediated perylenequinone biosynthesis in Shiraia mycelium culture

Summary

Scientists discovered that bacteria living inside medicinal mushroom fruiting bodies can trigger the production of powerful healing compounds called perylenequinones through direct physical contact. These compounds are being used to fight cancer and harmful bacteria through a therapy called photodynamic therapy. The study shows that when bacteria touch the mushroom’s cells, it causes the mushroom to produce more of these therapeutic compounds by creating controlled stress that activates specific genes.

Background

Perylenequinones (PQs) from Shiraia fruiting bodies are potent photosensitizers used in anticancer and antimicrobial photodynamic therapy. Although fruiting bodies harbor diverse endophytic bacteria, their interactions with the host fungus and effects on PQ production remain poorly understood.

Objective

To investigate the interaction between Shiraia sp. S9 and dominant Pseudomonas isolates, analyzing fungal transcriptional responses and PQ biosynthesis through in vitro confrontation bioassays and comparative assessment of contact versus non-contact co-culture systems.

Results

Direct physical contact was essential for PQ production, particularly extracellular secretion of hypocrellin A (HA), HC, and elsinochrome A-C. Bacterial contact induced ROS generation (O₂·⁻ and H₂O₂), resulting in 2.4-fold increase in total PQ yield (362.2 mg/L). RNA-seq identified 646 differentially expressed genes with enrichment in oxidative stress defense, carbohydrate metabolism, and membrane transport functions.

Conclusion

Contact-dependent ROS signaling by endophytic Pseudomonas regulates fungal secondary metabolism and PQ biosynthesis. This study provides the first evidence that direct physical contact between bacteria and fungi within fruiting bodies mediates enhanced production of bioactive perylenequinones through ROS-mediated mechanisms.
  • Published in:Bioresource and Bioprocess Journal,
  • Study Type:Experimental Research,
  • Source: PMID: 41003957, DOI: 10.1186/s40643-025-00946-w
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