By Marina Wang
Scientists have recently discovered a new type of photosynthesis that could change the search for alien life as well as improve engineered crops.
Photosynthesis typically occurs using a pigment called chlorophyll a which uses red light to convert carbon dioxide and water into sugar and oxygen. However, scientists from Imperial College London discovered that certain types of cyanobacteria, or blue-green algae, can perform photosynthesis using a different pigment called chlorophyll f under low-light conditions. Unlike chlorophyll a, chlorophyll f uses light from the near-infrared part of the spectrum.
The cyanobacteria capable of this kind of photosynthesis live in shaded areas such as bacterial mats in Yellowstone National Park or in beach rock in Australia. The researchers were able to grow the bacteria in a cupboard fitted with near-infrared lights.
“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,” said lead researcher Bill Rutherford. “This is textbook changing stuff.”
Astrobiologists searching for photosynthesis on other planets were restrained by something called a “red limit”, or the minimum amount of energy required for photosynthesis. Now, without this limit, astrobiologists can widen the scope of where they might be able to search, as darker planets with different wavelengths of light might be capable of harboring life.
The discovery might also improve agriculture by engineering crops to photosynthesize with a wider range of light. This could enable them to grow more efficiently in darker conditions.
“I did not expect that my interest in cyanobacteria and their diverse lifestyles would snowball into a major change in how we understand photosynthesis,” said Dennis Nürnberg, first author of the study. “It is amazing what is still out there in nature waiting to be discovered.”
The findings were published in Science on Thursday.
