SoylentNews

takyon [soylentnews.org] writes:

A newly discovered form of photosynthesis [imperial.ac.uk] could have implications for exoplanet/exomoon [soylentnews.org] habitability:

The vast majority of life on Earth uses visible red light in the process of photosynthesis, 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. As scientists have now discovered, it also occurs in a cupboard fitted with infrared LEDs in Imperial College London.

The standard, near-universal type of photosynthesis uses the green pigment, chlorophyll-a, both to collect light and use its energy to make useful biochemicals and oxygen. The way chlorophyll-a absorbs light means only the energy from red light can be used for photosynthesis.

Since chlorophyll-a is present in all plants, algae and cyanobacteria that we know of, it was considered that the energy of red light set the 'red limit' for photosynthesis; that is, the minimum amount of energy needed to do the demanding chemistry that produces oxygen. The red limit is used in astrobiology to judge whether complex life could have evolved on planets in other solar systems.

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.

Also at ScienceAlert [sciencealert.com].

Photochemistry beyond the red limit in chlorophyll f–containing photosystems [sciencemag.org] (DOI: 10.1126/science.aar8313) (DX [doi.org])

Original Submission