One major beneficial function of V is to allow the synthesis of an alternative nitrogenase when Mo is unavailable (Harwood, 2020). When there is a scarcity of Mo, some organisms are able to synthesize alternative forms of nitrogenase that replace Mo with V or use an Fe-only cofactor in place of the MoFe complex present in the Mo-dependent enzyme. These alternative types of nitrogenase appear to provide a back-up function since they are only found in Bacteria and Archaea that also express, usually as the preferred enzyme, a Mo-containing nitrogenase. 

Vanadium is often present as an oxyanion (vanadate) and this species is the cofactor for a family of V-dependent haloperoxidases (VHPOs) in marine algae and some bacteria (Wever et al., 2018). These enzymes play an important role in the generation of volatile organohalide compounds in marine systems, and thereby affect the biogeochemical cycling of the halides (Baumgartner & McKinnie, 2021; Wever et al., 2018). 

Vanadium is accumulated to high levels in certain marine invertebrates often called sea squirts (tunicates). In these organisms, V can accumulate to levels >300 mM. V is present in complexes with specific binding proteins (vanabins) within blood cells (vanadocytes) (Michibata et al., 2003; Ueki et al., 2015). Despite the presence of specific binding proteins, and a compartment specific accumulation, the physiological role of V in tunicates has not yet been satisfactorily explained (Rehder, 2015). 

 

Some Bacteria can use the V oxyanion vanadate as an electron acceptor in dissimilatory respiration (Rehder, 2015). 

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