Abstract
Sulfate reduction is an essential metabolism that maintains biogeochemical cycles in marine and terres-trial ecosystems.Sulfate reducers are exclusively prokaryotic,phylogenetically diverse,and may have evolved early in Earth's history.However,their origin is elusive and unequivocal fossils are lacking.Here we report a new microfossil,Qingjiangonema cambria,from～518-million-year-old black shales that yield the Qingjiang biota.Qingjiangonema is a long filamentous form comprising hundreds of cells filled by equimorphic and equidimensional pyrite microcrystals with a light sulfur isotope composition.Multiple lines of evidence indicate Qingjiangonema was a sulfate-reducing bacterium that exhibits similar patterns of cell organization to filamentous forms within the phylum Desulfobacterota,including the sulfate-reducing Desulfonema and sulfide-oxidizing cable bacteria.Phylogenomic analyses confirm sepa-rate,independent origins of multicellularity in Desulfonema and in cable bacteria.Molecular clock anal-yses infer that the Desulfobacterota,which encompass a majority of sulfate-reducing taxa,diverged～2.41 billion years ago during the Paleoproterozoic Great Oxygenation Event,while cable bacteria diverged～0.56 billion years ago during or immediately after the Neoproterozoic Oxygenation Event.Taken together,we interpret Qingjiangonema as a multicellular sulfate-reducing microfossil and propose that cable bacteria evolved from a multicellular filamentous sulfate-reducing ancestor.We infer that the diversification of the Desulfobacterota and the origin of cable bacteria may have been responses to oxy-genation events in Earth's history.
基金项目
国家自然科学基金(41890843)
国家自然科学基金(41890845)
国家自然科学基金(41930319)
国家自然科学基金(42242201)
国家自然科学基金(42272354)
Overseas Expertise Introduction Project for Discipline Innovation(the 111 Project)(D17013)
陕西省自然科学基金(2022JC-DW5-01)
National Science Foundation of USA(EAR-1554897)
NETL
NSTL
万方数据