Location: Fruit and Tree Nut ResearchTitle: Antifungal activity of different Xenorhabdus and Photorhabdus species against various fungal phytopathogens and identification of the antifungal compounds from X. szentirmaii
|CIMEN, HARUN - Adnan Mederes University|
|TOURAY, MUSTAPHA - Adnan Mederes University|
|SEBNEM, GULSEN - Adnan Mederes University|
|ERINCIK, OMER - Adnan Mederes University|
|WENSKI, SEBASTIAN - Goethe University|
|BODE, HELGE - Goethe University|
|Shapiro Ilan, David|
|HAZIR, SELCUK - Adnan Mederes University|
Submitted to: Applied Microbiology and Biotechnology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/16/2021
Publication Date: 7/12/2021
Citation: Cimen, H., Touray, M., Sebnem, G., Erincik, O., Wenski, S., Bode, H., Shapiro Ilan, D.I., Hazir, S. 2021. Antifungal activity of different Xenorhabdus and Photorhabdus species against various fungal phytopathogens and identification of the antifungal compounds from X. szentirmaii. Applied Microbiology and Biotechnology. vol 105: 5517-5528. https://doi.org/10.1007/s00253-021-11435-3.
Interpretive Summary: A number of serious fungal diseases attack crop plants and thereby limit yields. It is important to find new environmentally-friendly methods of controlling these diseases. A group of naturally occurring bacteria in the genera Xenorhabdus and Photorhabdus have been shown to suppress certain fungi. These bacteria are symbionts of beneficial nematodes (round worms) and are safe to human and the environment. In our study, we compared a wide array of these bacteria for their suppressive abilities against four major fungal diseases. The most potent bacterium was X. szentirmaii. Additionally, we identified some of the bioactive compounds that are responsible for the suppressive ability; the compounds are called fabclavines. This research indicates potential to use these bacteria or their byproducts as safe and effective natural fungicides.
Technical Abstract: Xenorhabdus and Photorhabdus spp., are enteric bacterial symbionts of Steinernema and Heterorhabditis nematodes, respectively. These bacteria produce an extensive set of natural products (NPs) with antibacterial, antifungal, antiprotozoal, insecticidal or other bioactivities when vectored into insect hemocoel by nematodes. We assessed the in vitro activity of different Xenorhabdus and Photorhabdus cell-free supernatants against important fungal phytopathogens, viz. Cryphonectria parasitica, Fusarium oxysporum, Rhizoctonia solani and Sclerotinia sclerotiorum and identified the bioactive antifungal compound/s present in the most effective bacterial supernatant using the easyPACId (easy promoter activated compound identification) approach against chestnut blight C. parasitica. Our data showed that supernatants from Xenorhabdus species were comparatively more effective than extracts from Photorhabdus in suppressing the fungal pathogens; among the bacteria assessed, X. szentirmaii was the most effective species against all tested phytopathogens especially against C. parasitica. Subsequent analysis revealed fabclavines as antifungal bioactive compounds in X. szentirmaii, generated by a polyketide synthase (PKS) and non-ribosomal peptide synthetase (NRPS) hybrid system. Fabclavines are broad-spectrum, heat-stable NPs that have great potential as biological control compounds against fungal plant pathogens. More studies are needed to assess the potential phytotoxicity of these compounds and effects on non-target organisms before commercialization.