Bacterial Communities in the Rhizosphere of Biofuel Crops as Evaluated by 16S rRNA Pyrosequencing.

We studied bacterial communities in soils cultivated with the following biofuel crops in different locations in Michigan: switchgrass, corn, soybean, canola and sunflower. Our objective was to evaluate the effect of biofuel crop, location and soil attributes on soil bacterial communities. 16S rRNA gene sequences have been amplified from community DNA with tagged-primers and sequenced by 454 technology, generating more than 300,000 sequences that have been used for analysis of community structure and composition. Twenty-four phyla were found in the studied soils and Acidobacteria, Proteobacteria, Verrucomirobia, Actinobacteria and Gemmatimonadetes were the most abundant. Sites were ordered based on data for these abundant phyla. The PCoA ordination explained 31% of the variability in the data. Bacterial communities were separated mainly by location and community structure was correlated to pH and soil nutrients such as Ca and Mg. Additional analysis showed that interactions between soil and crops and soil and location accounted for a great part of the explained variation of the data. The results indicate soil attributes play an important role in defining the structure of the studied communities.