Comparative analysis of bacterial communities in a potato field as determined by pyrosequencing

Background: Plants selectively attract particular soil microorganisms, in particular consumers of root-excreted compounds. It is unclear to what extent cultivar type and/or growth stage affect this process. Methodology / Principal Findings: DNA-based pyrosequencing was used to characterize the structure of bacterial communities in a field cropped with potato. The rhizospheres of six cultivars denoted Aveka, Aventra, Karnico, Modena, Premiere and Desiree, at three growth stages (young, flowering and senescence) were examined, in addition to corresponding bulk soils. Around 350,000 sequences were obtained (5,700 to 38,000 per sample). Across all samples, rank abundance distributions best fitted the power law model, which indicates a community composed of a few highly dominant species next to numerous rare species. Grouping of the sequences showed that members of the Actinobacteria, Alphaproteobacteria, next to as-yet-unclassified bacteria, dominated. Other groups that were consistently found, albeit at lower abundance, were Beta-, Gamma- and Deltaproteobacteria and Acidobacteria.