Diversity and Distribution of sulfate-reducing bacteria in Siders Pond, a meromictic salt pond

Genetic diversity and community structure of sulfate-reducing bacteria was investigated down the 12 meter water column of Siders Pond, a meromictic salt pond in Falmouth, MA. The physical and chemical gradients down this water column were also investigated, as they provide distinct niches for the microorganisms of Siders Pond. Microbial DNA was extracted from water samples at 12 depths. The dissimilatory sulfite reductase (dsr) gene was amplified via PCR, and dsr amplicons from three depths were subsequently cloned and sequenced. Of the 12 sampled depths, dsr was detected in the lower 10 samples, all of which were taken from the anoxic portion of the water column. The dsr sequences in 12 m were genetically distinct from the dsr found in the 4 and 8 m samples, and contained more diversity, exemplifying niche differentiation of sulfate-reducing bacteria along the profile of the water column. Using BLAST to compare Siders Pond dsr sequences to the GenBank database also showed that the closest relatives of Siders Pond sulfate-reducing bacteria were all isolated from human-impacted and organic-rich environments.