Cobalt: A must-have element for life and livelihood

Abstract

Cobalt is in the news—demanded by life’s metabolisms and seemingly irreplaceable in our technological world, yet the element averages only 25 ppm in Earth’s crust. So, impending deficiency for both life and technology is always looming. For humans and other animals, cobalt is the active center of vitamin B12 involved in methyl, and other, biochemistries. Although it is toxic in excess, we need ∼40 ng of Co daily, while other animals need their proportionate share, as do many microbes. In vitamin B12, the variable valence metal is coordinated within a corrin ring by four nitrogen ligands. The same Co-bearing core, although attached to iron sulfide, is central also to life’s acetyl coenzyme-A pathway (1). Indeed, Co had, and has, a vital part to play in the emergence and evolution of both the animate and the technological systems. Right down at the bottom of our evolutionary tree, the acetogens and the methanogens require such Co corrinoid iron sulfide enzymes for methyl biochemistry (2). This would be impossible without this Co(FeS) protein needed to mediate the attachment or detachment of a methyl group to or from carbon monoxide or another entity involved in the biosynthesis of acetyl-CoA (1, 2). In industry, cobalt is best known today as an obligatory constituent of batteries and smartphones as well as wear-resistant tools, whereas it was already playing a central role in the chemical industry as the “cobalt blue” of paints and pigments in the 19th century and as a catalyst in the 20th century. In PNAS, He et al. (3) revisit cobalt’s catalytic propensities as they explore the hydrothermal synthesis of long-chain hydrocarbons from sodium bicarbonate as substrate. Previous geochemical experiments on hydrothermal syntheses of hydrocarbons involved the hydrogenation of CO as in the Fischer–Tropsch reaction—a reaction assumed to operate during exothermic … [↵][1]1Email: michaeljrussell80{at}gmail.com. [1]: #xref-corresp-1-1

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