Hailiang Dong1
1China University of Geosciences, Beijing, China, 100083
Methane is a greenhouse gas and its cycling plays an important role in regulating surface temperature. Microorganisms are key drivers of methane, with methanogens and methanotrophs regulating most of atmospheric CH4 flux. Notably, many enzymes involved in these organisms depend on metal cofactors, which may be derived from minerals and rocks. Methanogenesis depends on metal-rich enzymes and cofactors, such as Fe, Ni, and Co. Inlaboratory media, these metals are supplied as dissolved salts; however, in early Earth environments, dissolved metal concentrations may have been highly variable, and solid-phase minerals and rocks may have served as important alternative sources. Experimental systems using peridotite, basalt, or granite have shown that mineral-derived metals are bioavailable and can sustain methanogenic activity. Methane oxidation is opposite of methanogenesis and is responsible for maintaining methane balance in nature. Aerobic methane oxidation requires Cu as an essential metal cofactor. However, in Archean and early Proterozoic oceans, soluble Cu concentrations were likely low because of sequestration in sulfide minerals. In modern redox-stratified environments, soluble Cu can be limited as well. Nevertheless, aerobic methanotrophs can remain active in such settings. Multiple studies have shown that aerobic methanotrophs can acquire Cu from sulfides through specialized Cu-binding compounds.
Key words: Cycling; Metal cofactor; Methane; methanogen; methanotroph; mineral
Author Profile
Hailiang Dong, Male, Professor, PhD, mainly engaged in mineralogy, geochemistry, and geomicrobiology research. Email: dongh@cugb.edu.cn
