Stressed by Heavy Metal

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Science  08 Oct 2010:
Vol. 330, Issue 6001, pp. 153
DOI: 10.1126/science.330.6001.153-c

When an ecosystem is stressed, do the more tolerant species benefit or do all species decline? In natural microbial communities, examples of both responses occur, but comparisons across field sites and experiments are difficult. In a relatively controlled natural setting, Gough and Stahl studied the stress response to metals in anoxic sediments of a eutrophic lake that are loaded with high but variable levels of metal contaminants from a nearby zinc smelter. By using a broad sequencing technique to identify dominant microbial sequences at the domain level, they found that across a range of metal concentrations, the communities were quite similar, and except in a few instances, the abundance and diversity of bacteria, archaea, and eukaryotes were uncorrelated with metal concentrations. In a notable exception within the archaeal fraction, cold-adapted Crenarchaeota were strongly correlated with high levels of zinc, arsenic, and copper. Although little is known about these freshwater anaerobes—even their metabolic role in the microbial communities is unclear—they appear to have a competitive advantage in their response to metal stress over other archaeal clades, including more common methanogens.

ISME J. 4, 10.1038/ismej.2010.132 (2010).

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