"We used to believe that microbes only consumed methane in marine anaerobic sediment if sulfate was present," said Emily Beal, graduate student in geoscience, Penn State. "But other electron acceptors, such as iron and manganese, are more energetically favorable than sulfate."
Beal, working with Christopher H. House, associate professor of geoscience, Penn State, and Victoria J. Orphan, assistant professor of geobiology, California Institute of Technology, incubated a variety of marine sediments to determine if there were microbes that could convert methane to carbon dioxide without using any sulfur compounds. They report their results in today's (July 10) issue of Science.
Using samples of marine sediment taken 20 miles off the California coast and about 1,800 feet deep near methane seeps in the Pacific, Beal incubated a variety of sediment systems including as controls, an autoclaved sterile sample, a sample with sulfate as a control and a sample that was sulfate, iron oxide and manganese oxide free, but live. She also incubated samples that were sulfate free but contained iron oxide or manganese oxide. She placed methane gas that contained the non-radioactive carbon-13 isotope in the empty space in the flasks above the sediment and tested any resulting carbon dioxide produced by the samples. All the carbon dioxide had the carbon-13 isotope and so came from the methane samples.The sterile control showed no activity, while the live control without sulfate showed minute activity. The sulfate control showed the most activity as expected, but both the iron and manganese oxide-laced samples showed activity, although less activity than the sulfate.
One reason they are important is that some of the carbon dioxide produced reacts with both the manganese and iron to form carbonates that precipitate and sequester carbon in the oceans. Even if the carbon dioxide escaped into the atmosphere, it is a less problematic greenhouse gas than methane.
On the early Earth, where oxygen was absent from the atmosphere, sulfates were scarce. Without sulfates, iron and manganese oxides may have been essential in converting methane to carbon dioxide.
"Sulfate comes mostly from oxidative weathering of rocks," said Beal. "Oxygen is needed for this to occur."
While manganese and iron oxides are made in today's oxygen atmosphere, they where also formed by photochemical reactions in a low oxygen atmosphere. These oxides were probably more abundant in the early Earth's oceans than sulfates.
While Beal has categorized the more than a dozen microorganisms living in the sediments she used, she does not know which of these microbes is responsible for consuming methane. It might be one bacteria or archaea species, or it may be a consortium of microbes. She is trying to identify the organisms responsible.
The National Science Foundation and the NASA Astrobiology Institute supported this work.
A'ndrea Elyse Messer | EurekAlert!
Researchers uncover protein-based “cancer signature”
05.12.2016 | Universität Basel
The Nagoya Protocol Creates Disadvantages for Many Countries when Applied to Microorganisms
05.12.2016 | Leibniz-Institut DSMZ-Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...
Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
05.12.2016 | Power and Electrical Engineering
05.12.2016 | Materials Sciences
05.12.2016 | Power and Electrical Engineering