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ARS Home » Southeast Area » Byron, Georgia » Fruit and Tree Nut Research » Research » Publications at this Location » Publication #346971

Research Project: Mitigating Alternate Bearing of Pecan

Location: Fruit and Tree Nut Research

Title: Thermo-stability, dose effects and shelf-life of antifungal compounds produced by the symbiotic bacterium Xenorhabdus szentirmaii

item HAZIR, SELCUK - Adnan Mederes University
item Shapiro Ilan, David
item Bock, Clive
item LEITE, LUIS - Instituto Biologicio - Brazil

Submitted to: American Phytopathological Society Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/17/2017
Publication Date: 12/1/2017
Citation: Hazir, S., Shapiro Ilan, D.I., Bock, C.H., Leite, L.G. 2017. Thermo-stability, dose effects and shelf-life of antifungal compounds produced by the symbiotic bacterium Xenorhabdus szentirmaii. American Phytopathological Society Annual Meeting. 107: S5.26.

Interpretive Summary:

Technical Abstract: Xenorhabdus spp bacteria are associated with Steinernematid nematodes and produce antifungal metabolites that protect nematode-infected cadavers from fungal colonization. Previous work demonstrated concentrated or cell-free metabolites of X. szentirmaii were toxic to fungal phytopathogens. We prepared cell free extracts by filtration and heating, determining 1. thermo-stability, 2. dose-response, and 3. shelf-life of antifungal metabolites of X. szentirmaii against Monilinia fructicola (cause of brown rot of peach and other stone fruit) and Glomerella cingulata (cause of antharacnose). Thermo-stability was determined by autoclaving bacterial culture broths (121oC and 15 psi for 15 minutes). Bacterial culture broths were filtered (0.22 mm Millipore filter) to remove bacterial cells. Subsequent growth of phytopathogens was measured on amended potato dextrose agar (PDA) containing 10% of the supernatants from the autoclaved or filtered samples. Autoclaving had no impact on antifungal activity. Autoclaved or filtrated supernatants were tested monthly for 9 months: activity was not altered when stored at room temperature, 4 oC or -20 oC. A dose-response study (10, 20, 40, 60, 80 and 100% supernatant-containing metabolite) demonstrated that a greater dose of supernatant increased antifungal activity. The supernatant of X. szentirmaii has potential as a bio-fungicide. The results demonstrate the metabolite(s) are thermo-stable, they have a long shelf-life.