The first new chlorophyll discovered in 60 years has been found on the Western Australia coast, in bacteria so primitive they may date back to the origins of life on Earth.
It is only the fifth known type of chlorophyll, the pigment molecules that allow plants to harvest energy from the sun through the process of photosynthesis, according to a new study published online today in the journal Science.
The rare find – named chlorophyll f - also extends the known ways in which photosynthesis can occur and may have evolved in extremely ancient times, notes one of the authors of the paper, Professor Brett Neilan, who heads the UNSW Centre for Cyanobacteria and Astrobiology.
"This is a really unusual chlorophyll because it can use the lowest light energy yet reported, in the non-visible red spectrum of sunlight," Professor Neilan says. "It means that photosynthesis can take advantage of a much wider spectrum of sunlight than we realised and can sustain life even under very poor light conditions.
"It may be no coincidence that chlorophyll f occurs in blue-green algae that are indistinguishable in structure from those in fossil stromatolites that are the oldest known evidence of life.
"We can't say at this stage but these algae may have evolved this capacity to harvest such low light energy under extreme conditions, perhaps deep in the ocean or when the Earth's atmosphere was much dimmer than it is today."
The study, led by Dr Min Chen from the University of Sydney, was focussed on the algae living in stromatolites – rock-like structures built up over many thousands of years by microbial communities - at Shark Bay. The oldest fossil stromatolites are also found in Western Australia and date back more than three billion years.
Professor Neilan has a longstanding interest in the Shark Bay microbial communities as part of a search for explanations into how early life evolved.
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