Saturday, August 21, 2010

Life in the Infrared

In1996 scientists were surprised to find a version of chlorophyll, chlorophyll d, in a cyanobacterium (blue-green algae or blue-green bacteria) that can photosynthesize light at 710nm, just in the infrared region. How it can get enough energy to photosynthesize is a mystery right now. It is possible that it acts more like chlorophyll a, passing on the captured energy to other chlorophyll molecules which then do the actual photosynthesis.

Recently, Dr Min Chen, from the University of Sydney, discovered in cyanobacterium living inside stromatolites another chlorophyll molecule which can absorb infrared light - this time deeper into the infrared range at 720 nm. This molecule, chlorophyll f, raises the same question as with chlorophyll d: how does it get enough energy from infrared light to photosynthesize oxygen? Or does it act as a helper, passing on the energy to other chlorophyll?

While this discovery has implications for biotechnology and bioenergy, it also has implications for life on other planets. As Dr. Chen remarks:
the fact that we have discovered a cyanobacterium that exploits a tiny modification in its chlorophyll molecule to photosynthesise in light that we cannot see, opens our mind to the seemingly limitless ways that organisms adapt to survive in their environment.
This helps expands the environmental range where we can look for life. For instance, it helps increase the possibility of life arising around class M stars (see Color of Life for more information). Yet more evidence that Dr. Ian Malcolm's (Jurassic Park) adage is correct: life will find a way.


Chen, Min, et. al. "A Red-Shifted Chlorophyll." Science Magazine. 19 August 2010. Web. 21 August 2010. <>


Anonymous said...

To make oxygenic photosynthesis on infrared light would require the combination of four photons into one reaction, which no terran organism has managed to do despite infrared photosynthesis having evolved multiple times independently, so there is a big risk that such worlds would be anoxic, with only microbial life.

Anonymous said...

Sorry for my comment. Now it has been iscovered a multicellular anaerobic animal, it seems that oxygen is not necessary for complex life.