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POSTERS: Phytobiomes

Carbon amendments alter composition and pathogen-inhibitory capacities of indigenous soil bacterial communities
Jose Pablo Dundore-Arias - University of Minnesota. Laura Felice- University of Minnesota, Linda Kinkel- University of Minnesota, Epidemiology and Ecology of Plant Diseases, Sarah Castle- University of Minnesota, Ruth Dill-Macky- University of Minnesota

Organic amendments can enhance microbial activity and improve soil health. However, the impacts of specific carbon amendments on indigenous microbiomes and their functions in agricultural soils remain underexplored. We investigated the effects of carbon amendments on antibiotic inhibitory capacities of indigenous soil Streptomyces, and composition of bacterial communities. Mesocosms were established in sterile jars with soil from two field sites varying in nutrient status, and were amended at intervals over nine months with glucose, fructose, malic acid, a nutrient mixture, or water control. In initially low-nutrient soils, carbon amendments increased frequencies of Streptomyces inhibitory against both bacterial (Streptomyces scabies) and fungal (Fusarium oxyxporum) pathogens. Sequencing of 16S rRNA genes showed that community composition differed significantly among carbon-amended and non-amended soils. Carbon type and dose had significant effects on bacterial community composition in low-nutrient soils, while communities were only responsive to differences in carbon substrates among initially high-nutrient soils. In total, these results suggest that nutrient additions to soil may play an important role in disease management by enhancing pathogen-inhibitory microbial communities in agricultural soils, but the effects vary with nutrient type, dose, and initial soil nutrient status.