Exotic bacteria that do not rely on oxygen may have played an important role in determining the composition of Earth’s early atmosphere, according to a theory that UChicago researcher Albert Colman is testing in the scalding hot springs of a volcanic crater in Siberia.
He has found that bacteria at the site produce as well as consume carbon monoxide, a surprising twist that scientists must take into account as they attempt to reconstruct the evolution of Earth’s early atmosphere.
Colman, an assistant professor in geophysical sciences, joined an American-Russian team in 2005 working in the Uzon Caldera of eastern Siberia’s Kamchatka Peninsula to study the microbiology and geochemistry of the region’s hot springs. Colman and his colleagues focused on anaerobic carboxydotrophs — microbes with a physiology as exotic as their name. They use carbon monoxide mostly for energy, but also as a source of carbon for the production of new cellular material.
This carbon monoxide-based physiology results in the microbial production of hydrogen, a component of certain alternative fuels. The research team thus also sought to probe biotechnological applications for cleaning carbon monoxide from certain industrial waste gases and for biohydrogen production.
“We targeted geothermal fields,” Colman says, “believing that such environments would prove to be prime habitat for carboxydotrophs due to the venting of chemically reduced, or in other words, oxygen-free and methane-, hydrogen-, and carbon dioxide-rich volcanic gases in the springs.”
The team did discover a wide range of carboxydotrophs. Paradoxically, Colman found that much of the carbon monoxide at the Kamchatka site was not bubbling up with the volcanic gases; instead “it was being produced by the microbial community in these springs,” he says. His team began considering the implications of a strong microbial source of carbon monoxide, both in the local springs but also for the early Earth.
“This important transition enabled a widespread diversification and proliferation of metabolic strategies and paved the way for a much later climb in oxygen to levels that were high enough to support animal life,” Colman says.
The processing of carbon monoxide by the microbial community could have influenced atmospheric chemistry and climate during the Archean, an interval of Earth’s history that preceded the Great Oxidation Event.
Previous computer simulations rely on a primitive biosphere as the sole means of removing near-surface carbon monoxide produced when the sun’s ultraviolet rays split carbon dioxide molecules. This theoretical sink in the biosphere would have prevented substantial accumulation of atmospheric carbon monoxide.
“But our work is showing that you can’t consider microbial communities as a one-way sink for carbon monoxide,” Colman says. The communities both produce and consume carbon monoxide. “It’s a dynamic cycle.”
Colman’s calculations suggest that carbon monoxide may have nearly reached percentage concentrations of 1 percent in the atmosphere, tens of thousands of times higher than current concentrations. This in turn would have exerted influence on concentration of atmospheric methane, a powerful greenhouse gas, with consequences for global temperatures.Toxic Concentrations
“A much larger fraction of the microbial community would’ve been exposed to higher carbon monoxide concentrations and would’ve had to develop strategies for coping with the high concentrations because of their toxicity,” Colman says.
Colman and UChicago graduate student Bo He have conducted fieldwork in both Uzon and California’s Lassen Volcanic National Park. Colman has most recently journeyed to Kamchatka for additional fieldwork in 2007 and 2010.
“This fantastic field site has a wide variety of hot springs,” he says. “Different colors, temperatures, chemistries, different types of micro-organisms living in them. It’s a lot like Yellowstone in certain respects.” Lassen’s springs have a narrower range of acidic chemistries, yet microbial production of carbon monoxide appears to be widespread in both settings.
Collaborator Frank Robb of the University of Maryland, Baltimore, lauds Colman for his “boundless enthusiasm” and for his “meticulous preparation,” much-needed qualities to ensure the safe transport of delicate instruments into the field.
Some of the microbial life within the caldera’s complex hydrothermal system may survive in even more extreme settings than scientists have observed at the surface, Colman says. “One thing we really don’t know very well is the extent to which microbial communities beneath the surface influence what we see at the surface, but that’s possible as well,” Colman says. “We know from culturing deep-sea vent microbes that they can live at temperatures that exceed the temperatures we’re observing right at the surface, and some of the turn out to metabolize carbon monoxide.”
The National Science Foundation and the National Aeronautics and Space Administration’s Astrobiology Institute have funded Colman’s Kamchatka research. The work offers insights into astrobiology, the study of the potential for life on other worlds, by showing how organisms might thrive in extreme environments beyond Earth, including the subsurface of Mars, Jupiter’s moon Europa, or even planets orbiting other stars.
By Steve Koppes
Steve Koppes | EurekAlert!
Water - as the underlying driver of the Earth’s carbon cycle
17.01.2017 | Max-Planck-Institut für Biogeochemie
Modeling magma to find copper
13.01.2017 | Université de Genève
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
Many pathogens use certain sugar compounds from their host to help conceal themselves against the immune system. Scientists at the University of Bonn have now, in cooperation with researchers at the University of York in the United Kingdom, analyzed the dynamics of a bacterial molecule that is involved in this process. They demonstrate that the protein grabs onto the sugar molecule with a Pac Man-like chewing motion and holds it until it can be used. Their results could help design therapeutics that could make the protein poorer at grabbing and holding and hence compromise the pathogen in the host. The study has now been published in “Biophysical Journal”.
The cells of the mouth, nose and intestinal mucosa produce large quantities of a chemical called sialic acid. Many bacteria possess a special transport system...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
17.01.2017 | Earth Sciences
17.01.2017 | Materials Sciences
17.01.2017 | Architecture and Construction