Enigmatic persistence of aerobic methanotrophs in oxygen-limiting freshwater habitats

Abstract

Methanotrophic bacteria mitigate emissions of the potent greenhouse gas methane (CH4) from a variety of anthropogenic and natural sources, including freshwater lakes, which are large sources of CH4 on a global scale. Despite a dependence on dioxygen (O2) for CH4 oxidation, abundant populations of putatively aerobic methanotrophs have been detected within microoxic and anoxic waters and sediments of lakes. Experimental work has demonstrated active aerobic methanotrophs under those conditions, but how they are able to persist and oxidize CH4 under O2 deficiency remains enigmatic. In this review, we discuss possible mechanisms that underpin the persistence and activity of aerobic methanotrophs under O2-limiting conditions in freshwater habitats, particularly lakes, summarize experimental evidence for microbial oxidation of CH4 by aerobic bacteria under low or no O2, and suggest future research directions to further explore the ecology and metabolism of aerobic methanotrophs in O2-limiting environments.

Methane-Driven Perchlorate Reduction by a Microbial Consortium

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Pond Water Microbiome Taxa Profiles and Antibiotic Resistance Genes Associated with Acidity and Tannins

“…Studies estimate that ponds comprise 30 percent of earth's standing fresh water. Freshwater microbes play important roles as producers, consumers and scavengers (4), and they mediate production and consumption of greenhouse gases such as methane (5,6).…”