Comparison of bacterial soil communities between vineyards and their surrounding semi-natural areas

Soil microbial processes play important roles in maintaining soil structure and ecosystem functions where microbiota is influenced by management, plant cover and invertebrates. Comparing the extent of divergence between soil bacteria in vineyards and in semi-natural margins in the same areas was the key objective of this work. Soil samples were collected in 12 vineyards and in their non-cropped surroundings. Farms were located in two neighbouring groups of hills, renowned for their wine quality: the Euganean Hills, with soils of prevalent volcanic origin, and the Berici Hills, with marine sedimentary genesis. Soil bacterial communities were determined based on the 16S rRNA gene analysis through the 454 pyrotag sequencing of the V1-V3 hypervariable region. Soil physical and chemical parameters, fungal communities, and macro- and meso-fauna of the vineyards were also studied, and statistical analyses highlighted interesting correlations between some bacterial taxa and soil characteristics, including the presence of different species of earthworms. Weighted UniFrac distance between soil bacterial communities was calculated, and the related UPGMA tree and PCoA plot showed that the majority of the semi-natural secondary deciduous woodlot soils clustered together, indicating that these, although geographically distant, presented more similar bacterial communities comparing to their respective nearest vineyard soil. Some groups were present with significantly different abundances in vineyard and semi-natural soils: Alphaproteobacteria, Acidobacteria, Bacteroidetes, Chloroflexi, Gammaproteobacteria, Gemmatimonadetes, and few other phyla. Within these, some families were decisive in determining differences. Overall, more than 800 bacterial genera and more than 4000 bacterial species were approximated through rarefaction curves. This study provides novel insights into how environment and soil management can affect and shape soil microbial community composition. This work was carried out within the ‘Veneterroir’ project, PSR 2007-2013 of the EU funding to Veneto Region