Belt Katharina, Flematti Gavin R, Bohman Björn, Chooi Heng, Roper Margaret M, Dow Lachlan, Truman Andrew W, Wilkinson Barrie, Singh Karam B, Thatcher Louise F
Commonwealth Scientific and Industrial Research Organisation (CSIRO) Agriculture and Food, Floreat, Western Australia, Australia.
School of Molecular Sciences, The University of Western Australia, Crawley, Western Australia, Australia.
Microb Biotechnol. 2025 Mar;18(3):e70082. doi: 10.1111/1751-7915.70082.
Bacteria and fungi produce a wide range of specialised metabolites, including volatile organic compounds (VOCs) that can act as signals or act directly to inhibit niche-competing microbes. Despite their ecological importance, most VOCs involved as signalling compounds remain uncharacterised. We have previously screened a collection of Actinobacteria strains sourced from Western Australia for their ability in vitro to suppress the growth of plant fungal pathogens. Here we explored the potential of four of the most active strains to produce antifungal metabolites by growing the strains on a range of nutrient-containing media. A casein-based (CYPS) culture medium was found to induce the production of antifungal compounds with high activity against Sclerotinia sclerotiorum, a major necrotrophic fungal pathogen of crops such as canola. We further observed that VOCs were produced that influenced pH and affected the bacterium-fungus interaction. The presence of Sclerotinia induced further VOC production in the Actinobacteria. Solid-phase microextraction (SPME) coupled with gas chromatography-mass spectrometry (GC-MS) analysis identified 2,4,6-trimethylpyridine, a compound not identified previously from Actinobacteria, which showed antifungal activity against different isolates of S. sclerotiorum and increased the pH of the medium. Overall, this study showed that Actinobacteria or their volatile products have the potential to be used in the protection of crops against S. sclerotiorum.
细菌和真菌会产生多种特殊代谢产物，包括挥发性有机化合物（VOCs），这些化合物可作为信号分子，或直接作用以抑制生态位竞争微生物。尽管它们在生态学上具有重要意义，但大多数作为信号化合物的挥发性有机化合物仍未得到表征。我们之前筛选了一批源自西澳大利亚的放线菌菌株，考察它们在体外抑制植物真菌病原体生长的能力。在此，我们通过在一系列含营养物质的培养基上培养这四种活性最高的菌株，探究它们产生抗真菌代谢产物的潜力。结果发现，一种基于酪蛋白的（CYPS）培养基能诱导产生对核盘菌具有高活性的抗真菌化合物，核盘菌是油菜等作物的一种主要坏死性真菌病原体。我们进一步观察到，产生的挥发性有机化合物会影响pH值并影响细菌与真菌的相互作用。核盘菌的存在会诱导放线菌产生更多的挥发性有机化合物。固相微萃取（SPME）结合气相色谱 - 质谱（GC - MS）分析鉴定出2,4,6 - 三甲基吡啶，这是一种此前未从放线菌中鉴定出的化合物，它对不同分离株的核盘菌均表现出抗真菌活性，并使培养基的pH值升高。总体而言，这项研究表明放线菌或其挥发性产物有潜力用于保护作物免受核盘菌侵害。
