Denaturing gradient gel electrophoresis (DGGE) band patterns obtained with specific primers for 16S rRNA gene fragments; from Archaea in sediment samples (a) and Deltaproteobacteria in cultures (b). The band patterns resulted from 40-70% (a) and 30-50% (b) denaturing gradients. The patterns are from two different seasons, rainy (R) and dry (D), and their respective depths are: 1) surface (0–5 cm), 2) 5–15 cm, 3) 15–25 cm and 4) 25–35 cm. Bands with numbers were excised from the gels and sequenced. Sequences were identified by the prefix describing the community sampled (Rw, Rs, Dw and Ds), technique used (da for DGGE and archaea) and ID number.