MYCOLab Ai Logo - gold and army green

Genomic characterization and fermentation study of the endophyte Stemphylium sp. (Aa22), a producer of bioactive alkyl-resorcinols

Summary

Scientists sequenced the complete genome of a fungus called Stemphylium sp. (strain Aa22) that lives inside wormwood plants without harming them. This fungus produces natural compounds called alkyl-resorcinols that can repel aphids and kill plant-damaging nematodes, making them potentially useful as organic pesticides. The researchers found the genetic instructions for making these compounds and determined that growing the fungus in liquid culture produces more of the useful compounds than growing it on rice, offering a promising path toward developing these natural biopesticides on a larger scale.

Background

Endophytic fungi are present in plant tissues without causing damage and produce diverse bioactive metabolites with potential biopesticide applications. Stemphylium sp. (strain Aa22), isolated from wormwood (Artemisia absinthium), was previously identified as a producer of bioactive alkyl-resorcinols including stemphol and stempholones A and B with antifeedant and nematicidal properties.

Objective

To complete the genome sequence of Stemphylium sp. Aa22, determine its taxonomic placement through phylogenomic analysis, identify biosynthetic gene clusters responsible for alkyl-resorcinol production, and optimize fermentation conditions to enhance production of these bioactive compounds.

Results

The near-complete genome of 34.1 Mb was assembled with 96.5% BUSCO completeness. Phylogenomic analysis placed Aa22 closest to Stemphylium lycopersici. Genome mining identified 38 biosynthetic gene clusters including a single type III polyketide synthase (T3PKS) likely responsible for alkyl-resorcinol biosynthesis. PDB liquid fermentation yielded the highest extract yields with high levels of stempholone A, while rice solid fermentation produced primarily lipid-based compounds without alkyl-resorcinols.

Conclusion

The T3PKS identified in the Aa22 genome is a candidate for future manipulation to enhance bioactive alkyl-resorcinol production. Liquid PDB fermentation is superior to solid-state fermentation for production of target compounds, while talcum powder addition suppresses stempholone A production. Further optimization of culture conditions and transcriptomic validation of the T3PKS gene are needed for biotechnological application.
  • Published in:PLoS One,
  • Study Type:Genomic and Fermentation Study,
  • Source: PMID: 40961083, DOI: 10.1371/journal.pone.0323031
Scroll to Top