Vanadium and the Nitrogen Cycle

To date, only the role of vanadium in biogenic nitrogen fixation has been established unambiguously. In addition, there are a few reports on a putative importance of vanadium in (bacterial) nitrate reductases, otherwise a domain of molybdenum. These reports are based on investigations which remain to be backed up. They are nonetheless briefly addressed, with a question mark, in Section 4.4.2. 

alternative substrates (such as alkynes, nitriles, isonitriles and azide)  

In a Brief note on the catalysis of the biological nitrogen fixation from 1933, Hans Bortels communicated the following observation 

WeitereUntersuchungen iiberdie Bedeutung von Molybdan, Vanadium, Wolfram undanderenErdaschenstoffen fur stickstoffbindende und andere Mikroorganismen. 

A role of tungsten could later be ruled out, and earlier findings of minor effects by tungsten were traced back to impurities of tungsten present in the culture media, due to the difficulty of separating molybdenum and tungsten completely. 

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