Doe Science news source
The DOE Science News Source is a Newswise initiative to promote research news from the Office of Science of the DOE to the public and news media.
  • 2017-05-01 10:05:50
  • Article ID: 673855

Microbes Making the Most of Their Energy Sources

Understanding an enigmatic energy-harnessing process in microorganisms, to inform biofuels research

  • Credit: Image courtesy of Saroj Poudel

    A generalized electron bifurcation reaction. An electron donor provides two electrons that are bifurcated simultaneously to two acceptor molecules with lower energy and higher energy in a hypothetical enzyme.

  • Credit: Image courtesy of Nathan Johnson

    Imagine a blue ball rolls downhill. Normally, it hits the yellow ball at the bottom of the hill, forcing that second sphere to go up the hill. In electron bifurcation, the energy from the blue ball goes into the hill.

Microorganisms are most typically thought of as biological nuisances that cause disease or spoil food. However, bacteria and other microorganisms are responsible for many important processes on Earth, without which the planet would be uninhabitable for any form of life.

Microorganisms can even be used to help bridge the gap towards more abundant and economical energy sources. This can occur by microbes that naturally generate biofuels such as hydrogen gas and methane. They can also be engineered to produce other biofuels such as butanol and biodiesel.

The key is that microorganisms need to harness, or conserve, energy in order to live — as all life does. It just so happens that they can also provide useful byproducts — resultant from their unique means of energy conservation — such as biofuels.

One mechanism of energy conservation — termed electron bifurcation — was not discovered until as recently as 2008. Before this discovery, there were only two known ways that life forms can conserve energy.

Several key biofuel targets for next-generation energy development are reliant on electron bifurcation as a means of energy conservation. As a result, this discovery ignited interest from the Department of Energy due to its relevance in hitting targets for next-generation energy development.

Now scientists at the Biological Electron Transfer and Catalysis (BETCy) Energy Frontier Research Center are beginning to understand how this process works and how it can aid in meeting next-generation energy demands.

Harnessing energy through electron bifurcation. To understand how electron bifurcation can be leveraged in biofuels research, an understanding of how it works is necessary.

A unifying theme of all life is that energy must be acquired to fuel biochemical processes that require energy. This is accomplished by coupling reactions that are favorable and provide energy, known as exergonic reactions, to reactions that are unfavorable and require energy input, known as endergonic reactions.

Imagine a blue ball rolls downhill. Normally, it hits the yellow ball at the bottom of the hill, forcing that second sphere to go up the hill. The energy is transferred between the two spheres in this example. In electron bifurcation, the hill, or enzyme, itself mediates this energy transfer from the blue ball to the yellow ball. In the ball analogy, the energy would power an escalator that simultaneously takes the yellow ball up the hill. The hill manages the energy transfer and separates the motion of both balls, allowing both events to occur instantaneously and separately. 

Electron bifurcation is similar in this regard. It is unique, however, in that the energy released from the exergonic reaction involves the direct transfer of electrons, and energy is conserved to simultaneously power the unfavorable reaction that also involves the direct transfer of electrons.

To conceptualize electron bifurcation, imagine two hills with a ball at the top of one hill and one in between the hills. By pushing the first one downhill, the impact pushes the other ball up the other hill. However, this process happens simultaneously in electron bifurcation. Perhaps more directly analogous, imagine the first ball is rolled downhill and that energy is transferred to the hill where it powers an escalator that simultaneously conveys the second ball up the other hill. The hill, in this example, mediates the energy transfer and separates the movements of both balls.

Analogously, electron bifurcation proceeds through the simultaneous transfer of electrons to both exergonic (downhill) and endergonic (uphill) reaction pathways. The process occurs within a single protein structure, or enzyme, that consists of multiple protein components, or subunits. Recalling the above example, the enzyme acts as the hill that mediates energy transfer. By coupling the two electron transfer reactions within a single enzyme simultaneously, energy loss that would otherwise escape as heat is minimized. Efficiency is critical for bifurcation because the organisms that perform it tend to live in environments where there is little energy. Thus, every bit of energy that is harnessed is crucial for survival.

Understanding the mechanisms behind electron bifurcation. Unraveling the mechanisms that allow electron bifurcation to occur in microorganisms has clear biotechnological and bio-energy implications. Understanding how microorganisms minimize energy loss during chemical reactions will enable the design of more efficient bio-inspired energy technologies. More directly, several electron bifurcating enzymes are important biotechnological and bio-energy targets. Gaining insight into how these enzymes function at the molecular level will provide a framework for enhancing their utilization in energy science.

Scientists at the BETCy Energy Frontier Research Center are investigating hydrogenases, which are a type of bifurcating enzyme that catalyze the production of hydrogen gas during cellular metabolism in microorganisms. Hydrogenases display high rates of hydrogen production and are thus highly sought-after bio-energy targets. This microbially produced hydrogen can then be harnessed and used as an alternative fuel source.

Interestingly, some hydrogenases catalyze hydrogen production through electron bifurcation (or rather, a version of bifurcation that operates in reverse as the above example). Yet, other than the discovery of the process in hydrogenases, little is known about how it occurs at the molecular level.

Recently, BETCy scientists compared the gene and protein repertoires of microbes that contain hydrogenases (bifurcating and non-bifurcating). The team’s goal was to better understand which hydrogenase enzyme components are determinants of the ability to bifurcate. These comparisons indicated that, aside from the enzyme subunit that catalyzes hydrogen production, additional enzyme protein components were likely necessary for bifurcating ability.

The team found that the presence of protein subunits that contain specific electron transferring inorganic components (coordinated iron and sulfur molecules) appear to be one key to bifurcation. In addition, organic electron transferring subunits (termed flavins — naturally occurring pigments) also appeared to be key to bifurcation ability. In other types of bifurcating enzymes, these electron transferring protein components are also almost certainly integral to the bifurcating process.

Untangling how electrons taken from a single source are sent down two different transfer pathways is a major focus of bifurcation research. Naturally, electrons should be transferred through the exergonic (downhill) pathway without active interference, forcing them towards the endergonic (uphill) pathway. One idea being investigated by BETCy involves an electron “gating” mechanism. Gating by the protein subunits would allow the transfer and separation of each set of electrons towards endergonic and exergonic pathways. This is where the iron-sulfur and flavin electron transfer components of the enzymes become important. These co-factors then mediate the transfer of electrons through each of these pathways.

Thus, analogous to the ball and hill example, the first electron transfer downhill would drive an enzyme change that simultaneously forces the other electron up the other hill.

Clearly, electron bifurcation represents an intriguing energy transfer process in biology. Understanding how this process occurs, as the BETCy team is investigating, promises significant advances in understanding biological energy transfer. Further, a more complete understanding of these processes holds substantial promise for bio-inspired energy advances.


Peters et al. This work was supported as part of the Biological Electron Transfer and Catalysis (BETCy) Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. P.W.K. was supported by the U.S. Department of Energy contract with the National Renewable Energy Laboratory.

Poudel et al. This work was supported as part of the Biological Electron Transfer and Catalysis Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences. The mass spectrometry facility at Montana State University receives funding from the Murdock Charitable Trust and National Institutes of Health of the Centers of Biomedical Research Excellence program.

More Information: 

Peters JW, AF Miller, AK Jones, PW King, and MW Adams. 2016. “Electron Bifurcation.” Current Opinion in Chemical Biology 31:146-152. DOI: 10.1016/j.cbpa.2016.03.007

Poudel S, M Tokmina-Lukaszewska, DR Colman, M Refai, GJ Schut, PW King, PC Maness, MW Adams, JW Peters, B Bothner, and ES Boyd. 2016. “Unification of [FeFe]-Hydrogenases into Three Structural and Functional Groups.” Biochimica et Biophysica Acta 1860(9):1910-1921. DOI: 10.1016/j.bbagen.2016.05.034

This item, written by Dan Colman, is part of Frontiers in Energy Research, a newsletter for the Energy Frontier Research Centers created by early career members of the centers. See

  • Filters

  • × Clear Filters

Discovered: A Quick and Easy Way to Shut Down Instabilities in Fusion Devices

Article describes use of second neutral beam injector to suppress instabilities on the NSTX-U

Researchers Create Molecular Movie of Virus Preparing to Infect Healthy Cells

A research team has created for the first time a movie with nanoscale resolution of the three-dimensional changes a virus undergoes as it prepares to infect a healthy cell. The scientists analyzed thousands of individual snapshots from intense X-ray flashes, capturing the process in an experiment at the Department of Energy's SLAC National Accelerator Laboratory.

Nanotechnology Gives Green Energy a Green Color

Solar panels have tremendous potential to provide affordable renewable energy, but many people see traditional black and blue panels as an eyesore. Architects, homeowners and city planners may be more open to the technology if they could install colorful, efficient solar panels, and a new study, published this week in Applied Physics Letters, brings us one step closer. Researchers have developed a method for imprinting existing solar panels with silicon nanopatterns that scatter green light back toward an observer.

New 3-D Simulations Show How Galactic Centers Cool Their Jets

Scientists at Berkeley Lab and Purdue University developed new theories and 3-D simulations to explain what's at work in the mysterious jets of energy and matter beaming from the center of galaxies at nearly the speed of light.

Are Your Tweets Feeling Well?

Study finds opinion and emotion in tweets change when you get sick, a method public health workers could use to track health trends.

"Getting to 80%" on Energy Cutbacks Cannot Occur Unless Behaviors Change

California's plan to cut energy consumption by 80 percent by 2050 cannot be achieved with current proposed policy changes because most solutions focus on changing technologies rather than changing behavior, a new UC Davis study suggests.

New Battery Material Goes with the Flow

Scientists at the U.S. Department of Energy's (DOE) Argonne National Laboratory have engineered a new material to be used in redox flow batteries, which are particularly useful for storing electricity for the grid. The material consists of carefully structured molecules designed to be particularly electrochemically stable in order to prevent the battery from losing energy to unwanted reactions.

Simulation Demonstrates How Exposure to Plasma Makes Carbon Nanotubes Grow

PPPL research performed with collaborators from Princeton University and the Institute for Advanced Computational Science at the State University of New York at Stony Brook has shown how plasma causes exceptionally strong, microscopic structures known as carbon nanotubes to grow.

Night Vision for Bird- & Bat-Friendly Offshore Wind Power

The ThermalTracker software analyzes video with night vision, the same technology that helps soldiers see in the dark, to help birds and bats near offshore wind turbines.

Drone Tech Offers New Ways to Manage Climate Change

An innovation providing key clues to how humans might manage forests and cities to cool the planet is taking flight. Cornell researchers are using drone technology to more accurately measure surface reflectivity on the landscape, a technological advance that could offer a new way to manage climate change.

  • Filters

  • × Clear Filters

Kathryn Hastie Wins Spicer Award for Lassa Virus Work at SLAC's X-Ray Synchrotron

Kathryn Hastie, staff scientist at The Scripps Research Institute, has spent the last decade studying how the deadly Lassa virus - which causes up to half a million cases of Lassa fever each year in West Africa - enters human cells via a cell surface receptor.

Southern Research to Play Key Role in Low Cost Carbon Fiber Project

Southern Research's Energy & Environment division (E&E) will participate as a subcontractor to WRI to provide renewable acrylonitrile -- the key raw material needed to produce the highest quality carbon fibers -- produced from biomass-derived second generation sugars.

Newly Upgraded Laser Allows Scientists to Peer Further Into the Extreme Universe at SLAC's LCLS

Scientists at the Department of Energy's SLAC National Accelerator Laboratory recently upgraded a powerful optical laser system used to create shockwaves that generate high-pressure conditions like those found within planetary interiors. The laser system now delivers three times more energy for experiments with SLAC's ultrabright X-ray laser, providing a more powerful tool for probing extreme states of matter in our universe.

Three Brookhaven Lab Scientists Selected to Receive Early Career Research Program Funding

Three scientists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory have been selected by DOE's Office of Science to receive significant research funding through its Early Career Research Program.

Upcoming 232nd ECS Meeting to Feature International Energy Summit, Nobel Laureate Lecture

The 232nd ECS Meeting will include 49 topical symposia and over 2,300 technical presentations, including the 7th International Electrochemical Energy Summit, the Society's inaugural OpenCon and Hack Day events, and plenary lecture delivered by former U.S. Secretary of Energy and Nobel Prize Laureate Steven Chu.

PNNL Scientist Jiwen Fan Receives DOE Early Career Research Award

Jiwen Fan of the Department of Energy's Pacific Northwest National Laboratory has been selected to receive a 2017 Early Career Research Program award from the U.S. Department of Energy. Fan will use the award to study severe thunderstorms in the central United States - storms that produce large hail, damaging winds, tornadoes, and torrential rainfall.

Three SLAC Scientists Receive DOE Early Career Research Grants

Three scientists at the Department of Energy's SLAC National Accelerator Laboratory will receive DOE Early Career Research Program grants for research to find evidence of cosmic inflation, understand how plasmas excite particles to high energies and develop a way to accelerate particles in much shorter distances with terahertz radiation.

Four ORNL Researchers Receive DOE Early Career Funding Awards

Four Oak Ridge National Laboratory researchers specializing in nuclear physics, fusion energy, advanced materials and environmental science are among 59 recipients of Department of Energy's Office of Science Early Career Research Program awards.

Missouri S&T Professor Earns Patent for Energy Storage Technology

ceramic engineering professor at Missouri University of Science and Technology has received a federal patent for his latest innovation, a multi-layer ceramic capacitor that could help boost energy storage in applications ranging from pulse power devices to military hardware.

James Peery Named Chief Scientist of the Global Security Directorate at Oak Ridge National Laboratory

James Peery, who has led critical national security programs at Sandia National Laboratories and Los Alamos National Laboratory, has been selected as the chief scientist of the Global Security Directorate at Oak Ridge National Laboratory.

  • Filters

  • × Clear Filters

Creating a Molecular Super Sponge, From the Ground Up

A new uranium-based metal-organic framework, NU-1301, could aid energy producers and industry.

Physicists Move Closer to Listening in on Sub-Atomic Conversation

Calculations of a subatomic particle called the sigma provide insight into the communication between subatomic particles deep inside the heart of matter.

Meet the Director: Chuck Black

This is a continuing profile series on the directors of the Department of Energy (DOE) Office of Science User Facilities. These scientists lead a variety of research institutions that provide researchers with the most advanced tools of modern science including accelerators, colliders, supercomputers, light sources and neutron sources, as well as facilities for studying the nano world, the environment, and the atmosphere.

Making an Ultra-small Silicon "Chip"

A new polymer, created with a structure inspired by crystalline silicon, may make it easier to build better computers and solar cells.

How to Keep a Vital Diagnostic Isotope in Stock

Researchers succeed in producing larger quantities of a long-lived radioisotope, titanium-44, that generates a needed isotope, scandium-44g, on demand.

When Strontium Is Away, Iridium Comes Out to Play

Developing a highly active and acid-stable catalyst for water splitting could significantly impact solar energy technologies.

On Track Towards a Zika Virus Vaccine

Antibody's molecular structure reveals how it recognizes the Zika virus

Quantum Computing Building Blocks

Scientists invented an approach to creating ordered patterns of nitrogen-vacancy centers in diamonds, a promising approach to storing and computing quantum data.

Scientists Program Yeast to Turn Plant Sugars into Biodiesel

Redox metabolism was engineered in Yarrowia lipolytica to increase the availability of reducing molecules needed for lipid production.

Soils Could Release Much More Carbon than Expected as Climate Warms

Deeper soil layers are more sensitive to warming than previously thought.


Saturday May 20, 2017, 12:05 PM

Rensselaer Polytechnic Institute Graduates Urged to Embrace Change at 211th Commencement

Rensselaer Polytechnic Institute (RPI)

Monday May 15, 2017, 01:05 PM

ORNL, University of Tennessee Launch New Doctoral Program in Data Science

Oak Ridge National Laboratory

Friday April 07, 2017, 11:05 AM

Champions in Science: Profile of Jonathan Kirzner

Department of Energy, Office of Science

Wednesday April 05, 2017, 12:05 PM

High-Schooler Solves College-Level Security Puzzle From Argonne, Sparks Interest in Career

Argonne National Laboratory

Tuesday March 28, 2017, 12:05 PM

Champions in Science: Profile of Jenica Jacobi

Department of Energy, Office of Science

Friday March 24, 2017, 10:40 AM

Great Neck South High School Wins Regional Science Bowl at Brookhaven Lab

Brookhaven National Laboratory

Wednesday February 15, 2017, 04:05 PM

Middle Schoolers Test Their Knowledge at Science Bowl Competition

Argonne National Laboratory

Friday January 27, 2017, 04:00 PM

Haslam Visits ORNL to Highlight State's Role in Discovering Tennessine

Oak Ridge National Laboratory

Tuesday November 08, 2016, 12:05 PM

Internship Program Helps Foster Development of Future Nuclear Scientists

Oak Ridge National Laboratory

Friday May 13, 2016, 04:05 PM

More Than 12,000 Explore Jefferson Lab During April 30 Open House

Thomas Jefferson National Accelerator Facility

Monday April 25, 2016, 05:05 PM

Giving Back to National Science Bowl

Ames Laboratory

Friday March 25, 2016, 12:05 PM

NMSU Undergrad Tackles 3D Particle Scattering Animations After Receiving JSA Research Assistantship

Thomas Jefferson National Accelerator Facility

Tuesday February 02, 2016, 10:05 AM

Shannon Greco: A Self-Described "STEM Education Zealot"

Princeton Plasma Physics Laboratory

Monday November 16, 2015, 04:05 PM

Rare Earths for Life: An 85th Birthday Visit with Mr. Rare Earth

Ames Laboratory

Tuesday October 20, 2015, 01:05 PM

Meet Robert Palomino: 'Give Everything a Shot!'

Brookhaven National Laboratory

Tuesday April 22, 2014, 11:30 AM

University of Utah Makes Solar Accessible

University of Utah

Wednesday March 06, 2013, 03:40 PM

Student Innovator at Rensselaer Polytechnic Institute Seeks Brighter, Smarter, and More Efficient LEDs

Rensselaer Polytechnic Institute (RPI)

Friday November 16, 2012, 10:00 AM

Texas Tech Energy Commerce Students, Community Light up Tent City

Texas Tech University

Wednesday November 23, 2011, 10:45 AM

Don't Get 'Frosted' Over Heating Your Home This Winter

Temple University

Wednesday July 06, 2011, 06:00 PM

New Research Center To Tackle Critical Challenges Related to Aircraft Design, Wind Energy, Smart Buildings

Rensselaer Polytechnic Institute (RPI)

Friday April 22, 2011, 09:00 AM

First Polymer Solar-Thermal Device Heats Home, Saves Money

Wake Forest University

Friday April 15, 2011, 12:25 PM

Like Superman, American University Will Get Its Energy from the Sun

American University

Thursday February 10, 2011, 05:00 PM

ARRA Grant to Help Fund Seminary Building Green Roof

University of Chicago

Tuesday December 07, 2010, 05:00 PM

UC San Diego Installing 2.8 Megawatt Fuel Cell to Anchor Energy Innovation Park

University of California San Diego

Monday November 01, 2010, 12:50 PM

Rensselaer Smart Lighting Engineering Research Center Announces First Deployment of New Technology on Campus

Rensselaer Polytechnic Institute (RPI)

Friday September 10, 2010, 12:40 PM

Ithaca College Will Host Regional Clean Energy Summit

Ithaca College

Tuesday July 27, 2010, 10:30 AM

Texas Governor Announces $8.4 Million Award to Create Renewable Energy Institute

Texas Tech University

Friday May 07, 2010, 04:20 PM

Creighton University to Offer New Alternative Energy Program

Creighton University

Wednesday May 05, 2010, 09:30 AM

National Engineering Program Seeks Subject Matter Experts in Energy

JETS Junior Engineering Technical Society

Wednesday April 21, 2010, 12:30 PM

Students Using Solar Power To Create Sustainable Solutions for Haiti, Peru

Rensselaer Polytechnic Institute (RPI)

Wednesday March 03, 2010, 07:00 PM

Helping Hydrogen: Student Inventor Tackles Challenge of Hydrogen Storage

Rensselaer Polytechnic Institute (RPI)

Thursday February 04, 2010, 02:00 PM

Turning Exercise into Electricity

Furman University

Thursday November 12, 2009, 12:45 PM

Campus Leaders Showing the Way to a Sustainable, Clean Energy Future

National Wildlife Federation (NWF)

Tuesday November 03, 2009, 04:20 PM

Furman University Receives $2.5 Million DOE Grant for Geothermal Project

Furman University

Thursday September 17, 2009, 02:45 PM

Could Sorghum Become a Significant Alternative Fuel Source?

Salisbury University

Wednesday September 16, 2009, 11:15 AM

Students Navigating the Hudson River With Hydrogen Fuel Cells

Rensselaer Polytechnic Institute (RPI)

Wednesday September 16, 2009, 10:00 AM

College Presidents Flock to D.C., Urge Senate to Pass Clean Energy Bill

National Wildlife Federation (NWF)

Wednesday July 01, 2009, 04:15 PM

Northeastern Announces New Professional Master's in Energy Systems

Northeastern University

Friday October 12, 2007, 09:35 AM

Kansas Rural Schools To Receive Wind Turbines

Kansas State University

Thursday August 17, 2006, 05:30 PM

High Gas Prices Here to Stay, Says Engineering Professor

Rowan University

Wednesday May 17, 2006, 06:45 PM

Time Use Expert's 7-Year Fight for Better Gas Mileage

University of Maryland, College Park

Showing results

0-4 Of 2215