Tech & Science

Hunt for Alien Life: Everything We Know About Photosynthesis Could Be Wrong

The discovery of a new way that bacteria can absorb infrared light and turn it into energy has transformed scientific understanding of life on Earth and could change the way humans hunt for alien life.

Plants use a process called photosynthesis to generate sugars from carbon dioxide and water, which they use as fuel. Until now, this was thought to be driven only by red light, but a team of researchers at Imperial College London discovered a type of photosynthesis that uses light from the infrared spectrum.

“The new form of photosynthesis made us rethink what we thought was possible,” said biochemist Bill Rutherford, a co-author of the study, which was published in the journal Science. “It also changes how we understand the key events at the heart of standard photosynthesis. This is textbook changing stuff.”

Beach-rock-0618 A section of beach rock that shows cyanobacteria growing deep inside the rock. Scientists discovered a new way that bacteria can absorb infrared light and turn it into energy. Dennis Nuernberg

This type of photosynthesis was detected in blue-green algae found in shady areas in Yellowstone National Park in the U.S. and growing deep into beach rock in Australia.

Normal photosynthesis is largely carried out by the green pigment chlorophyll-a, which gives plants their coloring.

All plants and photosynthetic bacteria have chlorophyll-a and scientists have long thought that there was a “red limit” on photosynthesis. Astrobiologists have even used the “red limit” to assess whether complex life could have developed on far away planets outside of our solar system, but it looks like the researchers at Imperial College London have disproven this.

They found that under the right conditions, another pigment called chlorophyll-f can also perform photosynthesis, even without the red light that normally helps the organisms produce energy.

The team of scientists tested these abilities by putting cyanobacteria inside cupboards under infrared lights.

“Finding a type of photosynthesis that works beyond the red limit changes our understanding of the energy requirements of photosynthesis,” said Andrea Fantuzzi, co-author of the study.

Aside from expanding the search for alien life, this research could help with genetically engineering crops that can live in lower light conditions.

“It is amazing what is still out there in nature waiting to be discovered,” said another co-author of the study, Dennis Nürnberg, a life sciences professor at Imperial College London.

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