Featured Research

from universities, journals, and other organizations

New Possibilities For Hydrogen-producing Algae

Date:
March 25, 2009
Source:
Carnegie Institution
Summary:
Photosynthesis produces the food that we eat and the oxygen that we breathe -- could it also help satisfy our future energy needs by producing clean-burning hydrogen? Researchers studying a hydrogen-producing, single-celled green alga, Chlamydomonas reinhardtii, have unmasked a previously unknown fermentation pathway that may open up possibilities for increasing hydrogen production.

Scanning electron microscope image, showing an example of the green algae Chlamydomanas reinhardtii.
Credit: Dartmouth Electron Microscope Facility, Dartmouth College / Courtesy of Wikimedia Commons

Photosynthesis produces the food that we eat and the oxygen that we breathe ― could it also help satisfy our future energy needs by producing clean-burning hydrogen? Researchers studying a hydrogen-producing, single-celled green alga, Chlamydomonas reinhardtii, have unmasked a previously unknown fermentation pathway that may open up possibilities for increasing hydrogen production.

C. reinhartii, a common inhabitant of soils, naturally produces small quantities of hydrogen when deprived of oxygen. Like yeast and other microbes, under anaerobic conditions this alga generates its energy from fermentation. During fermentation, hydrogen is released though the action of an enzyme called hydrogenase, powered by electrons generated by either the breakdown of organic compounds or the splitting of water by photosynthesis. Normally, only a small fraction of the electrons go into generating hydrogen. However, a major research goal has been to develop ways to increase this fraction, which would raise the potential yield of hydrogen.

In the new study by Dubini et al., published in the Journal of Biological Chemistry, researchers at the Carnegie Institution's Department of Plant Biology, the National Renewable Energy Laboratory (NREL), and the Colorado School of Mines (CSM), examined metabolic processes in a mutant strain that was unable to assemble an active hydrogenase enzyme.

The researchers, who include Alexandra Dubini (NREL), Florence Mus (Carnegie), Michael Seibert (NREL), Matthew Posewitz (CSM), and Arthur Grossman (Carnegie), expected the cell's metabolism to compensate by increasing metabolite flow along other known fermentation pathways, such as those producing formate and ethanol as end products. Instead, the algae activated a pathway leading to the production of succinate, which was previously not associated with fermentation metabolism in C. reinhardtii. Notably, succinate, a widely used industrial chemical normally synthesized from petroleum, is included in the Department of Energy's list of the top 12 value added chemicals from biomass.

"We actually didn't know that this particular pathway for fermentation metabolism existed in the alga until we generated the mutant," says Carnegie's Arthur Grossman. "This finding suggests that there is significant flexibility in the ways that soil-dwelling green algae can metabolize carbon under anaerobic conditions. By blocking and modifying some of these metabolic pathways, we may be able to augment the donation of electrons to hydrogenase under anaerobic conditions and produce elevated levels of hydrogen."

Grossman points out that it makes evolutionary sense that a soil organism such as Chlamydomonas would have a variety of metabolic pathways at its disposal. Oxygen levels, nutrient availability, and levels of metals and toxins can be extremely variable in soils, over both the short and long term. "In such an environment", Grossman says, "these organisms must evolve flexible metabolic circuits; the variety of conditions to which the organisms are exposed might favor one pathway for energy metabolism over another, which would help the organism compete in the soil environment over evolutionary time."

Grossman led the effort to generate a fully sequenced Chlamydomonas genome, which has allowed researchers to identify key genes encoding proteins involved in both fermentation and hydrogen production. Grossman feels that it is of immediate importance to generate new mutant strains to help us understand how we may be able to alter fermentation metabolism and the production of hydrogen. NREL's Michael Seibert, the project's Principal Investigator, observed that "the overarching goal of the work is to gain a fundamental understanding of the total suite of metabolic processes occurring in Chlamydomonas and how they interact; this discovery effort will lead to the development of novel ways to produce renewable hydrogen and other biofuels, which will benefit all of us".

"These are really exciting times in the field," says Matthew Posewitz. "The tools developed at Carnegie and by other groups in the field are presenting unprecedented opportunities for scientists to make important advances in our understanding of the basic biology of organisms such as Chlamydomonas."

As an energy source to potentially replace fossil fuels, hydrogen would greatly reduce the emission of greenhouse gases. Proponents of algal-based hydrogen production point out that, unlike ethanol produced from crops, it would not compete with food production for agricultural land.

The Project is being supported by the US Department of Energy's GTL Program within the Office of Biological and Environmental Research.


Story Source:

The above story is based on materials provided by Carnegie Institution. Note: Materials may be edited for content and length.


Journal Reference:

  1. Alexandra Dubini, Florence Mus, Michael Seibert, Arthur R. Grossman and Matthew C. Posewitz. Flexibility in Anaerobic Metabolism as Revealed in a Mutant of Chlamydomonas reinhardtii Lacking Hydrogenase Activity. Journal of Biological Chemistry, 2008; 284 (11): 7201 DOI: 10.1074/jbc.M803917200

Cite This Page:

Carnegie Institution. "New Possibilities For Hydrogen-producing Algae." ScienceDaily. ScienceDaily, 25 March 2009. <www.sciencedaily.com/releases/2009/03/090324171556.htm>.
Carnegie Institution. (2009, March 25). New Possibilities For Hydrogen-producing Algae. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2009/03/090324171556.htm
Carnegie Institution. "New Possibilities For Hydrogen-producing Algae." ScienceDaily. www.sciencedaily.com/releases/2009/03/090324171556.htm (accessed October 20, 2014).

Share This



More Earth & Climate News

Monday, October 20, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Traditional Farming Methods Gaining Ground in Mali

Traditional Farming Methods Gaining Ground in Mali

AFP (Oct. 20, 2014) He is leading a one man agricultural revolution in Mali - Oumar Diatabe uses traditional farming methods to get the most out of his land and is teaching others across the country how to do the same. Duration: 01:44 Video provided by AFP
Powered by NewsLook.com
Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-Fuel Impala

3BL Media (Oct. 20, 2014) Hey, Doc! Sewage, Beer and Food Scraps Can Power Chevrolet’s Bi-fuel Impala Video provided by 3BL
Powered by NewsLook.com
White Rhino's Death In Kenya Means Just 6 Are Left

White Rhino's Death In Kenya Means Just 6 Are Left

Newsy (Oct. 20, 2014) Suni, a rare northern white rhino at Ol Pejeta Conservancy, died Friday. This, as many media have pointed out, leaves people fearing extinction. Video provided by Newsy
Powered by NewsLook.com
Beijing Marathon Runners Brave Hazardous Air Pollution

Beijing Marathon Runners Brave Hazardous Air Pollution

AFP (Oct. 19, 2014) Tens of thousands of runners battled thick smog at the Beijing Marathon on Sunday, with some donning masks as the levels of PM2.5 small pollutant particles soared to 16 times the maximum recommended level. Duration: 00:54 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins