Related Experiment Video
Updated: Jul 11, 2026
08:11
Adaptation at the Extremes of Life: Experimental Evolution with the Extremophile Archaeon Sulfolobus acidocaldarius
Published on: June 14, 2024
Early Archaean microorganisms preferred elemental sulfur, not sulfate
Pascal Philippot1, Mark Van Zuilen, Kevin Lepot
1Equipe Géobiosphère Actuelle et Primitive, Institut de Physique du Globe de Paris, CNRS and Université Denis Diderot, 4 place Jussieu, 75005 Paris cedex, France. philippot@ipgp.jussieu.fr
Science (New York, N.Y.)
|September 18, 2007
Summary
Early life on Earth may have involved sulfur-disproportionating organisms, not just sulfate-reducing ones. Microscopic sulfides in ancient Australian rocks show unique sulfur isotopes, suggesting a novel microbial metabolism predating sulfate reduction.
Area of Science:
- Geochemistry
- Paleobiology
- Early Earth conditions
Background:
- Microscopic sulfides in the 3.49-billion-year-old Dresser Formation exhibit low 34S/32S ratios.
- These sulfides have been previously interpreted as evidence for early sulfate-reducing organisms.
Purpose of the Study:
- To investigate the origin of microscopic sulfides in the Dresser Formation.
- To re-evaluate the evidence for early microbial life based on sulfur isotopes.
Main Methods:
- Analysis of sulfur isotopic composition (34S/32S and Delta33S) in microscopic sulfides and host barite.
- Comparison of observed isotopic signatures with known biological and abiologic sulfur cycling processes.
Main Results:
- Microscopic sulfides display a mass-independent fractionation of sulfur (Delta33S) distinct from their host sulfate.
- The observed isotopic signature (negative delta34S and positive Delta33S) is inconsistent with sulfate reduction by microbes or abiologic sulfate reduction.
Conclusions:
- The studied sulfides likely originated from organisms that disproportionate elemental sulfur.
- This finding suggests an earlier and more diverse microbial sulfur metabolism than previously recognized.
Related Concept Videos
01:29Microbes and the Sulfur Cycle
Sulfur is a vital element in Earth's biogeochemical systems. It transitions through various inorganic states, including sulfate (SO₄²⁻), elemental sulfur (S⁰), and sulfide (S²⁻). Abiotic and biological mechanisms across oxic and anoxic environments intricately mediate these transformations. Sulfate, the most oxidized form of sulfur, is predominantly stored in rocks, marine sediments, and oceanic waters, acting as a long-term reservoir in the global sulfur cycle.In oxic environments,...
01:27Diversity of Archaea III
Crenarchaeota, a prominent phylum of Archaea, is remarkable for its ability to thrive in extreme environments characterized by high temperatures and acidity. These microorganisms inhabit sulfuric hot springs, volcanic systems, and submarine hydrothermal vents, where temperatures often exceed 100°C. The unique adaptations of Crenarchaeota not only allow survival under such extreme conditions but also provide insights into the mechanisms of life in primordial Earth-like environments.Morphological...
01:20Sulfur Assimilation
Sulfur is an essential element in biological systems, contributing to synthesizing key biomolecules, including amino acids such as cysteine and methionine, and cofactors such as coenzyme A and biotin. Microorganisms primarily assimilate sulfur as sulfate (SO₄²⁻) from the environment, which must undergo a series of biochemical transformations before it can be incorporated into cellular components. As sulfate is highly oxidized, it must undergo assimilatory sulfate reduction to become...
01:24Diversity of Archaea II
Archaea, one of the three domains of life, exhibit remarkable diversity and adaptability, thriving in both extreme and moderate environments. Historically, most identified archaea have been classified into two major phyla: Euryarchaeota and Crenarchaeota. However, recent molecular studies have expanded this classification to include three additional phyla: Thaumarchaeota, Nanoarchaeota, and Korarchaeota, each exhibiting unique characteristics and ecological roles.Thaumarchaeota: Mesophiles...
01:24Microbes and Other Elemental Cycles
Microbial activity plays a pivotal role in the biogeochemical cycling of iron and manganese, especially at the redox gradients characteristic of stratified aquatic environments. These cycles are driven by microbial transformations between oxidized and reduced forms of the metals, allowing organisms to exploit them for metabolic energy and structural purposes.Iron Cycling Across Redox GradientsIn neutral, oxygen-rich surface waters, iron is predominantly found in its oxidized, insoluble ferric...
01:30Diversity of Archaea I
Archaea, a domain of single-celled microorganisms, are classified into five major phyla based on genetic and biochemical characteristics: Euryarchaeota, Crenarchaeota, Thaumarchaeota, Korarchaeota, and Nanoarchaeota. Among these, the phylum Euryarchaeota is notable for its remarkable diversity in morphology, metabolism, and ecological adaptations.Morphological and Metabolic DiversityMembers of Euryarchaeota exhibit a variety of cellular shapes, including rods and cocci. Their metabolic pathways...