Multiple Metabolic Cooperations

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Science  03 Jun 2011:
Vol. 332, Issue 6034, pp. 1128-1129
DOI: 10.1126/science.332.6034.1128-d

The toxic liquids that ooze out of old mine workings have been fruitful hunting grounds for microbial ecologists, primarily because the range of organisms that can tolerate such extreme conditions is limited and makes for tractable wild ecosystems to study. Bertin et al. undertook a metagenomic investigation of the microflora in a stream biofilm exiting the former mine of Carnoulès in France. They found a community dominated by seven organisms with complementary and apparently intertwined metabolisms. Three strains allied to Thiomonas, Acidithiobacillus, and Gallionella are inorganic nitrogen and carbon dioxide fixers. These primary producers supply other members of the consortium with organic nutrients, in an apparently coordinated way: For example, an Acidobacteria clade possesses transporters for simple carbohydrates, whereas a Thiobacillus-like organism is equipped to handle complex carbohydrates. A candidate new species of Fodinabacter appears to make important contributions to recycling organic compounds released by other organisms, and in turn provides them with essential cofactors, such as cobalamin, which then activates iron oxidation in Acidiothiobacillus. The seven also seem to be represented by other genotypes, which indicates an ability to shift the metabolic emphasis when conditions change.

ISME J. 5, 10.1038/ismej.2011.51 (2011).

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