Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
2024752 | Soil Biology and Biochemistry | 2014 | 8 Pages |
Abstract
The relative contributions of the alternative (V- and Fe-only) and canonical (Mo-) nitrogenases to N2 fixation in natural environments are still largely unknown. Here we combine chemical and molecular approaches to examine their role in terrestrial ecosystems. Pure-culture studies show that while the R ratio (defined as RÂ =Â acetylene reduction rate/N2 fixation rate by nitrogenase) is highly variable, low R ratios (0.5Â <Â RÂ <Â 2) are usually an indication of alternative nitrogenase activity. Microcosm experiments with temperate soils showed low R ratios and a large increase in N2 fixation rates in response to vanadium amendments, indicating V-nitrogenase activity. Using RT-PCR, we were able to demonstrate expression of the V-nitrogenase, together with the Mo-nitrogenase, in these soils. An analysis of published R ratios showed that the contribution of alternative nitrogenases to asymbiotic N2 fixation in soils may be more prevalent than previously recognized.
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Authors
J.P. Bellenger, Y. Xu, X. Zhang, F.M.M. Morel, A.M.L. Kraepiel,