All posts tagged: microbial life

Scientists recreate Enceladus’s ocean and watch Earth microbes thrive

Scientists recreate Enceladus’s ocean and watch Earth microbes thrive

Published by Jenni Sidey

Laboratory experiments show that a methane-producing archaeon from Earth can grow under simulated Enceladus seafloor conditions at pH values as high as 11, far beyond its previously reported natural range. Water-rock reactions in the experiment produced hydrogen that fueled microbial metabolism, while Enceladus-like concentrations of dissolved inorganic carbon helped the organisms overcome the severe shortage of available carbon dioxide. The results do not show that life exists on Saturn’s moon, but they broaden the conditions considered potentially habitable and strengthen the case for future missions that directly sample Enceladus’s ocean-derived plumes. Beneath the frozen surface of Saturn’s moon Enceladus lies an ocean unlike anything familiar on Earth. It is dark, highly alkaline and separated from space by kilometers of ice, yet its chemistry may be surprisingly accommodating to life. Laboratory experiments now show that an Earth microorganism can grow under conditions designed to reproduce parts of the moon’s hydrothermal seafloor. The microbe survived at pH values reaching 11, producing methane while drawing energy and carbon from reactions involving water, rock, hydrogen and dissolved carbonate. Researchers …

Ancient ocean chemistry may explain how Earth kept its oxygen

Ancient ocean chemistry may explain how Earth kept its oxygen

Published by Jenni Sidey

Earth’s atmosphere did not become oxygen-rich in one clean transition. More than 2 billion years ago, oxygen repeatedly rose and fell as climate, ocean chemistry, microbes and nutrients pushed the planet through major environmental swings. A new study suggests phosphorus played a central role in determining whether those oxygen increases lasted. Researchers from UC Riverside, studying ancient South African rocks, found evidence that changing ocean conditions repeatedly recycled phosphorus into seawater. That nutrient could then support more photosynthetic life, leading to greater production of organic matter. When some of that carbon became buried in sediments instead of decomposing, oxygen remained behind in the atmosphere. The study, published in Nature Communications, combines measurements of different phosphorus pools with sulfur isotopes, redox-sensitive elements and biogeochemical modeling. Together, the evidence reveals a feedback among phosphorus, sulfur, climate and oxygen during one of the most important transitions in Earth’s history. Trends in atmospheric oxygenation and ocean redox conditions are based on Fe-S1 and redox-sensitive trace elements (this study) systematics. (CREDIT: Andrey Bekker et al, Nature Communications 2026) Oxygen rose …

Meteorite 200x larger than the dinosaur killer reshaped the course of evolution on Earth

Meteorite 200x larger than the dinosaur killer reshaped the course of evolution on Earth

Published by Jenni Sidey

A meteorite 50 to 200 times more massive than the one linked to the dinosaurs struck Earth 3.26 billion years ago. The impact triggered a tsunami, ocean heating and darkness, but it also carried phosphorus and moved iron-rich deep water toward the surface. Those nutrients may have helped iron-using microbes recover quickly, showing that early impacts could support life as well as destroy it. A meteorite far larger than the one linked to the dinosaurs struck Earth 3.26 billion years ago, yet the devastation may have briefly created better conditions for some of the planet’s earliest microbes. The S2 impactor measured an estimated 37 to 58 kilometers across and carried 50 to 200 times the mass of the Chicxulub object. Its collision unleashed a tsunami, heated the atmosphere, disturbed the oceans and darkened the surface with dust. Rock layers in South Africa’s Barberton Greenstone Belt record what followed. The evidence points to a disaster that damaged shallow-water life, then supplied iron and phosphorus that may have fueled a rapid microbial rebound. Drabon with students David …

50 years ago, did NASA’s Viking landers destroy the Martian life they were searching for?

50 years ago, did NASA’s Viking landers destroy the Martian life they were searching for?

Published by Jenni Sidey

Nearly half a century after NASA’s Viking landers touched Mars, one question shadows their experiments: Did they miss life, or did they destroy it while trying to prove it was there? Dirk Schulze-Makuch, an astrobiologist at Technical University Berlin, has proposed that Viking’s life-detection tests may have exposed native Martian microbes to lethal amounts of liquid water. Organisms adapted to an extremely dry world, he argues, might not have survived the treatment intended to reveal their metabolism. “NASA may have unwittingly uncovered life on Mars nearly 50 years ago and accidentally destroyed it before understanding its significance,” Schulze-Makuch argues. The idea challenges the assumptions behind the 1976 mission. Viking 1 and Viking 2 carried four experiments designed to search Martian soil for organic compounds, metabolic activity and changes associated with living organisms. Viking, Gas Chromatograph Mass Spectrometer. (CREDIT: National Air and Space Museum) Four tests produced an uneven picture The Gas Chromatograph Mass Spectrometer heated soil samples, separated the released compounds and identified molecules by their mass signatures. It found no organic molecules, a result …