Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Evolution upset: Oxygen-making microbes came last, not first

25.10.2002


Get ready to rewrite those biology textbooks – again. Although the "lowly" blue-green algae, or Cyanobacteria, have long been credited as one of Earth’s earliest life forms and the source of the oxygen in the early Earth’s atmosphere, they might be neither.

By creating a new genetic family tree of the world’s most primitive bacteria and comparing it to the geochemistry of ancient iron and sulfur deposits, Carrine Blank of Washington University has found evidence that instead of Cyanobacteria being very ancient, they may have appeared much later, perhaps as much as a billion years later, than previously assumed. Blank will present the results of her research at the annual meeting of the Geological Society of America in Denver on Tuesday, Oct. 29.

"What paleontologists and geologists have had to do is reconstruct evolutionary events because biologists haven’t had a very good evolutionary tree of bacteria," says Blank. To get a better family tree, Blank took advantage of growing genome archives and studied 38 genes in the whole gene sequences of 53 species of extant bacteria, including Cyanobacteria. By mapping out the rates of change in the slowest-changing genes, Blank was able to generate a bacterial evolutionary history that shows cyanobacteria branching off last.



If correct, Blank’s tree essentially flip-flops the traditional order in which bacteria appeared on the scene.

Traditionally, it has been thought that Cyanobacteria came on stage very early in Earth’s history, perhaps at least 3.5 billion years ago. They produced the first abundant oxygen molecules. All that oxygen bound to the abundant free iron in the oceans and rained to the seafloor – creating the economically important banded iron formations. The advent of atmospheric oxygen also caused sulfide minerals on land to break down into sulfates and wash into the oceans – where sulfur-loving bacteria gobbled them up. The earliest geological evidence for sulfur bacteria is changes in sulfur isotopes – indicating organisms are preferentially using isotopes of the element – that began about 2.4 billion years ago. This was followed by a sudden rise in oxygen in the atmosphere at about 2.2 or 2.3 billion years ago.

"The (traditional) model was that the cyanobacteria were present all the time," says Blank. Reasonable as all this sounds, it doesn’t match the genetic evolutionary tree, she says.

In Blank’s version of the story, the sulfur-loving bacteria came on the scene at about 2.4 billion years ago, and the Cyanobacteria came along at least 100 million years later, she says. Because banded iron formations were formed much earlier than these dates, Cyanobacteria are not likely to have led to their creation, she explains.

Blank’s model could explain the puzzling lack of actual cyanobacteria fossils in the earliest days of the banded iron formations. It could also resolve an apparent contradiction regarding the biochemistry of Cyanobacteria, says Blank. The contradiction is that cyanobacteria have a surprisingly advanced biochemistry that was the product of a long evolutionary history. In other words, cyanobacteria must have evolved from more primitive photosynthetic bacteria.

If Blank is correct, her revised evolutionary history of the bacteria raises a difficult question: If cyanobacteria came later, where did the Earth’s earliest oxidants come from which produced banded iron formations? There are many competing theories on this matter, Blank says. Among them are hypotheses that call on inorganic reactions in the oceans and the air to release limited amounts of oxidants. There is even the possibility that there was also an early and so-far undiscovered iron oxidizing microbe that may have produced banded iron formations as a result of their metabolism, Blank says.

Blank’s cyanobacteria research was conducted as part of her recent doctoral thesis at the University of California at Berkeley. Her bacterial phylogeny research is currently under review for publication in the journal Molecular Phylogenetics and Evolution. Blank is an Assistant Professor of Molecular Geobiology in the Department of Earth and Planetary Sciences at Washington University in St. Louis.


CONTACT INFORMATION

During the GSA Annual Meeting, Oct. 27-30, contact Christa Stratton at the GSA Newsroom in the Colorado Convention Center, Denver, Colorado, for assistance and to arrange for interviews: 303-228-8565.

The abstract for this presentation is available at: http://gsa.confex.com/gsa/2002AM/finalprogram/abstract_46069.htm

Post-meeting contact information:

Carrine Blank
Earth and Planetary Sciences
Washington University
blank@levee.wustl.edu
314-935-4456

Ann Cairns
Director of Communications
Geological Society of America
acairns@geosociety.org
303-357-1056


Ann Cairns | EurekAlert!
Further information:
http://gsa.confex.com/gsa/2002AM/finalprogram/abstract_46069.htm

More articles from Life Sciences:

nachricht New switch decides between genome repair and death of cells
27.09.2016 | University of Cologne - Universität zu Köln

nachricht A blue stoplight to prevent runaway photosynthesis
27.09.2016 | National Institute for Basic Biology

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

Im Focus: Complex hardmetal tools out of the 3D printer

For the first time, Fraunhofer IKTS shows additively manufactured hardmetal tools at WorldPM 2016 in Hamburg. Mechanical, chemical as well as a high heat resistance and extreme hardness are required from tools that are used in mechanical and automotive engineering or in plastics and building materials industry. Researchers at the Fraunhofer Institute for Ceramic Technologies and Systems IKTS in Dresden managed the production of complex hardmetal tools via 3D printing in a quality that are in no way inferior to conventionally produced high-performance tools.

Fraunhofer IKTS counts decades of proven expertise in the development of hardmetals. To date, reliable cutting, drilling, pressing and stamping tools made of...

Im Focus: Launch of New Industry Working Group for Process Control in Laser Material Processing

At AKL’16, the International Laser Technology Congress held in May this year, interest in the topic of process control was greater than expected. Appropriately, the event was also used to launch the Industry Working Group for Process Control in Laser Material Processing. The group provides a forum for representatives from industry and research to initiate pre-competitive projects and discuss issues such as standards, potential cost savings and feasibility.

In the age of industry 4.0, laser technology is firmly established within manufacturing. A wide variety of laser techniques – from USP ablation and additive...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Laser use for neurosurgery and biofabrication - LaserForum 2016 focuses on medical technology

27.09.2016 | Event News

Experts from industry and academia discuss the future mobile telecommunications standard 5G

23.09.2016 | Event News

ICPE in Graz for the seventh time

20.09.2016 | Event News

 
Latest News

New switch decides between genome repair and death of cells

27.09.2016 | Life Sciences

Nanotechnology for energy materials: Electrodes like leaf veins

27.09.2016 | Physics and Astronomy

‘Missing link’ found in the development of bioelectronic medicines

27.09.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>