After mashing up rock and algae chunks known as stromatolites, researchers have found a new type of chlorophyll, the pigment in plants that takes in light and provides energy for photosynthesis. Unlike its known cousins, this chlorophyll uses infrared light--that's a surprise to some researchers, who doubted that lower frequency infrared had enough energy to split water for photosynthesis's oxygen-creation.
"Nobody thought that oxygen-generating organisms were capable of using infrared light... ," says Samuel Beale, a molecular biologist at Brown University whose work centers in part on chlorophylls [but who was not involved with the study]. "I think what they found here is a new modification of chlorophyll that shows the flexibility of photosynthetic organisms to use whatever light is available." [Scientific American]
Though the paper only appeared yesterday in Science, some researchers already have grand plans for the molecule, called "chlorophyll f." Because f can harness the energy in lower frequency light (706 nanometer wavelength) and over half of the sun's light comes in infrared, the newly found chlorophyll might find use in solar cells. Comments Shuguang Zhang:
"It's like a wider net to catch more fish." He is currently working with Michael Grätzel of the Swiss Federal Institute of Technology in Lausanne, developer of low-cost dye-sensitised solar cells that use inorganic molecular dyes to absorb light in the same way that chlorophyll does. [New Scientist]
Chlorophyll f joins a previously known family of four: chlorophyll a, b, c, and d. Chlorophyll a is the most popular--appearing in green plants. It absorbs light in the blue (465 nanometer wavelength) and red (665 nanometer wavelength) parts of the spectrum, and reflects the green light we see. The other types each have a shifted spectrum, but even chlorophyll d, absorbing most light around 697 nanometers, doesn't reach chlorophyll f's range. Having the ability to absorb infrared might help the blue-green algae that produced chlorophyll f thrive in its stromatolites habitat, where water, sediment and other organisms may prevent other frequencies of light from reaching the algae.
“In nature this very small modification of the pigment happens, and then the organism can use this unique light,” says molecular biologist Min Chen of the University of Sydney in Australia. Chen and her colleagues identified the new pigment in extracts from ground-up stromatolites, the knobby chunks of rock and algae that can form in shallow waters. The samples were collected in the Hamelin pool in western Australia’s Shark Bay, the world’s most diverse stromatolite trove. [Science News]
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Image: flickr /robertpaulyoung