Photosynthesis produces the food that we consume and the oxygen that we breathe, does it help solve future energy needs by creating clean burning hydrogen?
Scientists are studying hydrogen-producing single-celled green algae, Chlamydomonas reinhardtii, which has discovered a new way of fermentation that could open up the possibility of increasing hydrogen production.
C. reinhartii, living in soil, produces a small amount of hydrogen when losing oxygen. Like yeast and other bacteria, under anaerobic conditions this algae concentrate energy from fermentation. During fermentation, hydrogen is released through the action of an enzyme called hydrogenase, powered by electrons generated by the breakdown of compounds or muscle or water splitting by photosynthesis. Normally, only a small fraction of electrons are converted into hydrogen.However, a major research goal is to develop methods to increase this amount of electrons, thereby producing higher hydrogen yields. In the new study of Dubini and other authors, published in the Journal of Biological Chemistry, researchers from the Carnegie Institution's Department of Plant Biology, National Renewable Energy Laboratory (NREL) ), and the Colorado Field School (CSM), have examined metabolic processes in a mutant line that are unable to form a hydrogenase enzyme.
Researchers, including Alexandra Dubini (NREL), Florence Mus (Carnegie), Michael Seibert (NREL), Matthew Posewitz (CSM), and Arthur Grossman (Carnegie), expect cell metabolism to compensate. cover by increasing the metabolic flow in other known fermentation ways, such as increasing formate and methane in the form of end products. Instead, the blue algae activated the fermentation pathway, leading to the formation of succinate, previously unrelated to fermentation metabolism in C. reinhardtii. In particular, succinate, a widely used industrial chemical to synthesize gasoline, is on the list of 12 energy-added chemicals of the Ministry of Energy.
Arthur Grossman said: 'We really don't know if this fermentation pathway exists in green algae until we create a mutant line. This finding shows the flexibility in how soil-dwelling green algae can metabolize carbon under anaerobic conditions. By blocking or altering some metabolic pathways, we can change the amount of electrons for hydrogenase under anaerobic conditions and increase hydrogen production '.
Grossman points out that it is very likely that soil organisms such as Chlamydomonas may have many different metabolic pathways. Oxygen concentrations, nutrient reserves, and levels of metal and toxins can vary in soil, in the short or long term. Grossman explains: 'In such an environment, these organisms must evolve its metabolic cycle, the different conditions in which the organism is exposed can lead to energy metabolism, giving birth. wrestling competition in the soil environment '.
Grossman directed the complete decoding of Chlamydomonas' genome, allowing researchers to identify key genes that encode proteins involved in fermentation and hydrogen production. Grossman thinks it is necessary to create new mutants to help us better understand how fermentation metabolism and hydrogen production can be changed. Michael Seibert of NREL, observed 'the overarching goal of the study is to gain a basic understanding of the excellent metabolic processes in Chlamydomonas, and how they interact, the study's findings will lead to develop new methods for making hydrogen and renewable bioenergy, which are of great benefit to us. '
Matthew Posewitz said: 'This is an exciting time. The tools developed at Carnegie and other groups are providing unprecedented opportunities for scientists to make significant advances in our understanding of organisms like Chlamydomonas'.
As an energy source that has the potential to replace fossil fuels, hydrogen can significantly reduce greenhouse gas emissions. The proposal to make hydrogen from algae shows that, unlike ethanol produced from plants, it does not compete with food production.
The project is funded by the Office of Biological and Environmental Research, GTL program of the US Department of Energy.
Refer:
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