Copper acquisition from mineral promotes aerobic methane oxidation

Aerobic microbial methane oxidation plays an important role in the global carbon cycle. This process is catalyzed by enzyme methane monooxygenase. Particulate methane monooxygenase requires copper as a cofactor. However, studies have shown aerobic methanotrophic activity in environments with low aqueous copper. Here we hypothesize that minerals can serve as a source of copper. This hypothesis is tested by incubating a particulate methane monooxygenase-obligate methanotroph Methylocystis parvus OBBP with chalcopyrite. Cell growth, methane oxidation, and copper concentrations were measured. Gene expression, protein expression, and metabolite profiles were characterized. The presence of chalcopyrite promoted cell growth and methane oxidation, with similar rates and extents to those of copper ion. OBBP extracted copper from chalcopyrite by secreting a chalkophore (copper-binding metabolite) through expressions of specific methanobactin gene clusters and proteins. These results provide insights into copper bioavailability and have important implications for methane cycling on early Earth and in modern environments. >i<Methylocystis parvus>/i<OBBP, a methanotroph bacteria extract copper from chalcopyrite through synthesis and secret of a copper-binding metabolite to support cell growth and aerobic microbial methane oxidation, according to gene and protein expression, and metabolites profile analysis.