A new type of photosynthesis has been discovered by an international team of
scientists. The discovery, led by Imperial College London, and involved
groups from Australia and France changes the understanding of basic
mechanism of photosynthesis.

Photosynthesis uses visible red light, but the new type uses near-infrared
light instead. It was detected in a wide range of cyanobacteria (blue-green
algae) when they grow in near-infrared light, found in shaded conditions
like bacterial mats in Yellowstone and in beach rock in Australia.
Scientists have discovered that it also occurs in a cupboard fitted with
infrared LEDs in Imperial College London.

Photosynthesis uses chlorophyll-a, both to collect light and make useful
biochemicals and oxygen. The way chlorophyll-a absorbs light means only the
energy from red light can be used for photosynthesis. Chlorophyll-a is
present in all known plants, algae, and cyanobacteria. Red light's energy
sets the 'red limit' for photosynthesis, which is the minimum amount of
energy needed to produce oxygen. However, when some cyanobacteria are grown
under near-infrared light, the standard chlorophyll-a-containing systems
shut down and different systems containing a different kind of chlorophyll,
chlorophyll-f, takes over.

Lead researcher Professor Bill Rutherford from the Department of Life
Sciences at Imperial said, "The new form of photosynthesis made us rethink
what we thought was possible. It also changes how we understand the key
events at the heart of standard photosynthesis. This is textbook changing
stuff."

[www.imperial.ac.uk]