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The Flower and Berry Microbiomes of Wild and Cultivated Cranberries in Southeastern Massachusetts

Scott Soby: Midwestern University

<div>Healthy plants host large and diverse populations of bacteria, but much of the attention that has been paid to plant-associated bacteria has centered on pathogenic bacteria, and the soil and rhizosphere microbiome. We examined bacterial populations on cranberry flower and fruit surfaces using culture-dependent and culture-independent approaches. Our results show that flowers and fruits harbor bacterial communities with limited diversity, but that the communities on each organ are significantly different. Proteobacteria, Firmicutes, Actinobacteria and Bacterioidetes were the most dominant bacterial phyla on both flowers and berry surfaces. Tenericutes, a phylum that includes the genus <a href=""><em>Phytoplasma</em></a>, were observed in appreciable numbers only in flowers. The most represented genera included <em>Pseudomonas</em>, <em>Burkholderia</em>, <em>Acinetobacter</em>, <em>Sphingomonas</em>, <em>Candidatus Phytoplasma</em>, <em>Bacteroides</em>, <em>Salinibacterium</em>, <em>Escherichia</em>, and <em>Bacillus</em>. Culture-dependent methods indicated that there are several notable shifts in population structure associated with maturation of berries on vines over the winter. Among the Gram negative bacteria, only g-proteobacteria (<em>Pseudomonas</em>, <em>Pantoea</em>, <em>Ewingella</em>, <em>Erwinia</em>) and b-proteobacteria (<em>Xylophilus,</em> <em>Delftia</em>) were present. Gram positive bacteria were limited to Firmicutes (<em>Bacillus</em>, <em>Lysinibacillus</em>, <em>Paenibacillus</em>), and Actinobacteria (<em>Curtobacterium,</em> <em>Leifsonia</em>).</div>