Figure 3: Detection of Desulfovibrio spp. in environmental samples by PCR amplification of the [NiFe] hydrogenase gene using primer pair Hyd1FHyd5R. (A) Negative image of an ethidium bromide-stained agarose gel with PCR products obtained from DNAs from bacteria isolated from a microbial mat (lane 5), bacteria grown under anaerobic conditions in wastewater treatment reactors (lanes 3, 6, and 7), bacteria grown under aerobic conditions in a wastewater treatment reactor (lane 4). Lanes 1 and 9 represent the PCR products obtained after amplification of the genomic DNAs from D. vulgaris BCMPS82 and D. desulfuricans A, respectively. Lanes 2 and 8 contain DNA size markers (Bio-Rad). (B) Results after hybridization analysis using the DIG-labelled oligonucleotide probe Hyd4F, whose target sequence is located with in the amplified region.