Chlamydomonas reinhardtii Katie Nenninger
Chlamydomonas reinhardtii, or “Chlamy”, is a single cell green algae. It uses photosynthesis as its main means for energy. Chlamy can also survive in the dark in acetate media. It is a spherical or ellipsoidal organism with two equal-sized flagella located on the anterior of the cell. These organisms contain cup shaped chloroplast, pyrenoids and “eyespots” which sense light. Chlamy are found in fresh water, damp soil, the sea and sometimes even snow. They survive many different environments. This organism is used very often as a model organism in biology because of its very fast generation time, robustness, grows both in the light and dark, and can reproduce sexually or asexually. Chlamydomonas reinhardtii is an ancestor of both plants and animals and retains many features from both, including the flagella and the photosynthetic ability.
Chlamy is being studied currently for alternate fuels and energies. One use of Chlamydomonas reinhardtii is for the production of oil. Algae can produce and store lipids that are very similar to vegetable oils. By manipulating this trait in this species, scientists are hoping to find ways to produce a large amount of lipids, without having to use food. Chlamy is not the best organism to use for oil production but due to it being a model organism is being studied extensively. The process for the production and storage of oil is still largely unknown and scientists hope the study of this organism will help to determine the pathway of this function.
Another use for Chlamy as an alternative energy is as a hydrogen producing organism. Hydrogen is currently one of the most promising alternative energy sources because it is a “clean” energy source. Under certain conditions and in the absence of oxygen, Chlamy can produce hydrogen using hydrogenase. This process is only active in the absence of oxygen and is very short lived. The positives to this process are that the organism needs only sunlight and water to produce hydrogen, and it releases no greenhouse gases in return. When there is no oxygen, the creation of extra electrons in the cell forms a gradient and there is a build up of electrons within the cell. This hydrogen producing process works as a safety valve to release the extra electrons created during sugar production. This is an 80% efficient method for hydrogen synthesis. The main problem with this problem is the fact that the mechanism lasts for a few seconds to a few minutes maximum. The reaction is stopped by oxygen that is also released from the sugar production. Oxygen is an inhibitor of hydrogenase and as soon as enough oxygen is again present in the cell the hydrogen production gets stopped. They are currently researching two methods of fixing this problem. Both look very promising so far. One method of keeping the hydrogen production going longer is to decouple the hydrogenase from photosynthesis. This keeps the oxygen accumulation from inhibiting the hydrogenase. You can also keep the oxygen from inhibiting the hydrogenase by changing the genetic structure of hydrogenase. The hydrogen production will then use the electron flux formed from the breakdown of the cells own stock starch. The other method scientists are currently studying to elongate the hydrogen production process is to interrupt the photosynthetic process. This inhibits oxygen from reaching a high enough level to inhibit the hydrogenase. Though problems exist at this time with this mechanism of hydrogen production, promising strides are being made towards using Chlamydomonas reinhardtii as an alternative energy source.
Anastasios Melis and Thomas Happe
Hydrogen Production. Green Algae as a Source of Energy
Plant Physiology 2001 127: 740-748.
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.
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