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 R=acetylene reduction rate/N2 fixation rate by nitrogenase) is highly variable, low R ratios (0.5<R<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.
Original language | English (US) |
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Pages (from-to) | 413-420 |
Number of pages | 8 |
Journal | Soil Biology and Biochemistry |
Volume | 69 |
DOIs | |
State | Published - Feb 2014 |
All Science Journal Classification (ASJC) codes
- Microbiology
- Soil Science
Keywords
- Acetylene reduction assay
- Alternative nitrogenase
- Molybdenum
- N method
- Nitrogen fixation
- Vanadium