LONDON, March 15 (UPI) -- New research suggests a primitive form of photosynthesis originated in much older bacteria than previously thought.
Performed by plants, algae and cyanobacteria, photosynthesis is the conversion of sunlight into energy. The conversion of water and carbon dioxide to sugar produces oxygen as byproduct. The widespread adoption of this form of photosynthesis flooded the atmosphere of early Earth with oxygen and enabled the development of more complex lifeforms.
But there is another type of photosynthesis which does not produce oxygen -- converting hydrogen, hydrogen sulfide or iron instead of water. A few strains of modern bacteria employ anoxygenic photosynthesis, and researchers believed the ancestors of these strains first evolved the strategy some 3.5 billion years ago.
New research, however, suggests even older, more primitive bacteria -- strains likely long extinct -- first used anoxygenic photosynthesis.
Tanai Cardona, a professor of life sciences at Imperial College London, came to the revelation after tracing the evolutionary history of BchF, a protein key to the process of anoxygenic photosynthesis. The rehashed evolutionary tree suggests anoxygenic photosynthesis developed before the evolution of most modern bacterial strains.
Cardona detailed the findings in the journal PLOS ONE.
"Pretty much every group of photosynthetic bacteria we know of has been suggested, at some point or another, to be the first innovators of photosynthesis," Cardona said in a press release. "But this means that all these groups of bacteria would have to have branched off from each other before anoxygenic photosynthesis evolved, around 3.5 billion years ago."
"My analysis has instead shown that anoxygenic photosynthesis predates the diversification of bacteria into modern groups, so that they all should have been able to do it," Cardona added. "In fact, the evolution of oxygneic photosynthesis probably led to the extinction of many groups of bacteria capable of anoxygenic photosynthesis, triggering the diversification of modern groups."