Metaproteomic characterization of theVitis vinifera rhizosphere.

The rhizosphere is a hotspot of microbial activity where the release of root exudates stimulates bacterial density and diversity. The majority of the bacterial cells in soil are viable, unculturable, but active. Proteomic tools could be useful in gaining information about microbial community activity and to better understand the real interactions between roots and soil. The aim of this work was to characterize the bacterial community associated with Vitis vinifera cv. Pinot Noir roots using a metaproteome approach. Our results confirmed the large potential of proteomics in describing the environmental microbial communities and their activities: in particular, we showed that bacteria belonging to Streptomyces, Bacillus, Bradyrhizobium, Burkholderia and Pseudomonas genera are the most active in protein expression. Concerning the biological activity of these genera in the rhizosphere, we observed the exclusive presence of the phosphorus metabolic process and the regulation of primary metabolic processes. To our knowledge, this is the first study reporting the rhizosphere proteome of V. vinifera, describing the bacterial community structure and activity of an important ecosystem for the Italian landscape, agriculture and economy.