The rise of atmospheric O_2 was a milestone in the history of life. Although O_2 itself is not a climate-active gas, its appearance would have removed a methane greenhouse present on the early Earth and potentially led to dramatic cooling. Moreover, by fundamentally altering the biogeochemical cycles of C, N, S and Fe, its rise first in the atmosphere and later in the oceans would also have had important indirect effects on Earth's climate. Here, we summarize major lines of evidence from the geological literature that pertain to when and how O_2 first appeared in significant amounts in the atm

The rise of atmospheric O[subscript 2] was a milestone in the history of life. Although O[subscript 2] itself is not a climate-active gas, its appearance would have removed a methane greenhouse present on the early Earth and potentially led to dramatic cooling. Moreover, by fundamentally altering the biogeochemical cycles of C, N, S and Fe, its rise first in the atmosphere and later in the oceans would also have had important indirect effects on Earth's climate. Here, we summarize major lines of evidence from the geological literature that pertain to when and how O[subscript 2] first appeared

The Great Oxidation Event marks the first substantial increase in atmospheric oxygen on Earth. Despite the oxygenic photosynthesis that emerged hundreds of million years before this event, the specific biogeochemical mechanisms responsible for maintaining low oxygen levels for an extended period remain elusive. Here, we show the critical role of urea as a nitrogen source for cyanobacteria, the cascading impact of nickel on abiotic urea production, and their combined effects on the proliferation of cyanobacteria leading to the great oxidation event. Urea formation was experimentally evaluated u

Recent progresses of studies on the rise of atmospheric oxygen during 2.4-2.1 billion years ago (the Great Oxidation Event), the Paleoproterozoic snowball Earth event occurred 2.3-2.2 billion years ago, and a possible relationship between them are reviewed and discussed. Formation of manganese ore deposits at 2.2 billion years ago suggests that the rise of oxygen may have occurred just after the Paleoproterozoic snowball Earth event and, also, an overshoot of the atmospheric oxygen level is suggested to have occurred 2.2-2.1 billion years ago. Numerical results with a coupled model of biogeoch

Around 2.4 billion years ago, cyanobacteria ignited a planetary revolution—the Great Oxidation Event (GOE)—by releasing oxygen into Earth’s atmosphere through photosynthesis

Abstract The anaerobic ammonium oxidation (anammox) bacteria can transform ammonium and nitrite to dinitrogen gas, and this obligate anaerobic process accounts for up to half of the global nitrogen loss in surface environments. Yet its origin and evolution, which may give important insights into the biogeochemistry of early Earth, remain enigmatic. Here, we performed a comprehensive phylogenomic and molecular clock analysis of anammox bacteria within the phylum Planctomycetes. After accommodating the uncertainties and factors influencing time estimates, which include implementing both a tradit

ABSTRACT Marine biofilms were newly revealed as a giant microbial diversity pool for global oceans. However, the cyanobacterial diversity in marine biofilms within the upper seawater column and its ecological and evolutionary implications remains undetermined. Here, we reconstructed a full picture of modern marine cyanobacteria habitats by re-analyzing 9.3 terabyte metagenomic data sets and 2,648 metagenome-assembled genomes (MAGs). The abundances of cyanobacteria lineages exclusively detected in marine biofilms were up to ninefold higher than those in seawater at similar sample size. Analyses revealed that cyanobacteria in marine biofilms are specialists with strong geographical and environmental constraints on their genome and functional adaption, which is in stark contrast to the generalistic features of seawater-derived cyanobacteria. Molecular dating suggests that the important diversifications in biofilm-forming cyanobacteria appear to coincide with the Great Oxidation Event (GOE), “boring billion” middle Proterozoic, and the Neoproterozoic Oxidation Event (NOE). These new insights suggest that marine biofilms are large and important cyanobacterial factories for the global oceans.IMPORTANCECyanobacteria, highly diverse microbial organisms, play a crucial role in Earth’s oxygenation and biogeochemical cycling. However, their connection to these processes remains unclear, partly due to incomplete surveys of oceanic niches. Our study uncovered significant cyanobacterial di