Metagenome of a Versatile Chemolithoautotroph from Expanding Oceanic Dead Zones

Abstract

Life in Dead Zones Oxygen minimum zones, or oceanic “dead zones,” are expanding. Marine dead zone expansion and intensification results in amplification of biological nitrogen and greenhouse gas production, with implications for marine fisheries' productivity and for climate balance. Little is known about the microbial communities mediating the underlying biogeochemistry of dead zones. Walsh et al. (p. 578 ) present metagenomic analyses of a ubiquitous, abundant, and uncultivated bacterium in oceanic dead zones. Similar bacteria, related to chemoautotrophic gill symbionts of deep-sea clams and mussels, play a role in sulfide detoxification in African shelf waters. Reconstruction of the carbon and energy metabolism of this enigmatic lineage revealed a metabolic repertoire mediating carbon sequestration, sulfur-detoxification, and biological nitrogen loss in oxygen-deficient oceanic waters.