Figure 6. Ethidium bromide–stained DGGE profiles of rDNA fragments of PCR products derived from DNA extracted from mesocosm-scale reactors that were inoculated with digester sludge using a 25–70% denaturant gradient gel. Lane 1 corresponds to community DNA obtained from the no-substrate control after 126 days of incubation in the absence of any added growth substrates. Lanes 2 and 3 correspond to community DNA obtained from duplicate aliquots of the 3-CB–amended digester mesocosm (SBZ1 and SBZ2) that were obtained after ~ 130 days of incubation and 3-CB biodegradation. The aliquots were perturbed with a high dose (~ 14 mM) of benzoate. Benzoate was completely degraded in the aliquots within 40 days and before the DNA was extracted. An arrow indicates the gel portion (SBZ1-D1) that was excised, reamplified, and sequenced. Sequence SBZ1-D1 was submitted to GenBank (http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db_nucleotide) with the accession number AY646238.