FIG. 1.

Assessment of bacterial communities in three agricultural soils as determined by PCR-DGGE analyses on the basis of three extraction methodologies: Smalla et al. (14) (S), Powersoil (P), and CIAT (C). Soils: Buinen (B), Valthermond (V), and Kollumerwaard (K). (A) Overall unweighted-pair group method using average linkages (UPGMA)-based clustering analysis. (B) UPGMA clustering per soil. (C) Venn diagrams indicating numbers of shared and method-specific bands across different soils. Letters above, below, and next to the circles indicate the soil and extraction method. Numbers in the circles and in the intercepts indicate numbers of method-specific and shared bands, respectively. The diagrams were generated by establishing the number of bands based on the presence of particular bands in at least two (+) or less than 2 (−) replicates per soil.