A new role for nitrogen fixers

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Science  29 May 2015:
Vol. 348, Issue 6238, pp. 986-987
DOI: 10.1126/science.348.6238.986-c

North American coniferous forests harbor large amounts of the bacteria called bradyrhizobia. This genus made its name as obligatory symbionts of legumes, able to snatch atmospheric nitrogen via the nif gene product and supply it as nitrate to the plant and to fertilize soils. In return, the bacterium's nod genes allow it to live within the safety of the plants' roots. But legumes are rare in coniferous forests. Nevertheless, VanInsberghe et al. discovered that diverse bradyrhizobia, all lacking nif and nod genes, occur abundantly in these forests' soils. They are not symbionts, but they have other metabolic talents, depending on their environment. The symbionts are instead the minority in the genus.

ISME J. 10.1038/ismej.2015.54 (2015).

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