August 25, 2014
Newly Discovered Hot Springs Bacteria Can Use Far-Red Light For Photosynthesis
redOrbit Staff & Wire Reports - Your Universe Online
A type of bacteria growing in a hot spring near Yellowstone National Park in Montana uses a previously unidentified process to harvest energy and produce oxygen from sunlight, according to new research published in a recent edition of the journal Science.
The bacteria grows in far-red light, researchers from the Pennsylvania State University, the University of California, Davis, and Montana State University report in their study, and their discovery could help scientists discover ways to improve plant growth, harvest energy from the Sun and better understand dense blooms growing on lakes.
“We have shown that some cyanobacteria, also called blue-green algae, can grow in far-red wavelengths of light, a range not seen well by most humans,” Penn State biotechnology, biochemistry and molecular biology professor Donald A. Bryant explained in a statement Thursday.
“Most cyanobacteria can't 'see' this light either. But we have found a new subgroup that can absorb and use it, and we have discovered some of the surprising ways they manipulate their genes in order to grow using only these wavelengths,” he added.
The new subgroup is known as Leptolyngbya, and Bryant and his colleagues report that this cyanobacterial strain completely alters its photosynthetic apparatus in order to use far-red light that has wavelengths longer than 700 nanometers (slightly longer than the range of light visible to most humans).
Their experiments revealed that these cyanobacteria replace 17 proteins in three major light-using complexes, while manufacturing new chlorophyll pigments capable of capturing the far-red light and also using pigments known as bilins in unusual ways. They are able to accomplish all of this by quickly activating several genes to modify cellular metabolism and switching off a large number of other genes, the researchers said.
Bryant and his colleagues have dubbed this process Far-Red Light Photoacclimation (FaRLiP), and they explain that since the genes that are activated determine which proteins will be produced by the organism, the massive changes in the bacteria’s available gene profile has a dramatic impact.
“Our studies reveal that the particular cyanobacterium that we studied can massively change its physiology and metabolism, and its photosynthetic apparatus,” Bryant explained. “It changes the core components of the three major photosynthetic complexes, so one ends up with a very differentiated cell that is then capable of growing in far-red light. The impact is that they are better than other strains of cyanobacteria at producing oxygen in far-red light.”
In fact, the researchers report that cells grown in far-red light produce 40 percent more oxygen when studied in far-red light than those grown in red light assayed under the same types of conditions. This discovery was made through various biological, genetic, physical, and chemical experiments, all focused on better understanding how this unusual photosynthesis system works.
The authors explained that their study of this process included biochemical analyses, spectroscopic analyses, studies of the structures and functions of proteins, profiles of gene-transcription processes, and sequencing and comparisons of cyanobacteria genomes. Bryant said their genome-sequence analysis of the various strains found an addition 13 types of cyanobacteria that are also capable of using far-red light for photosynthesis.
The Leptolyngbya cyanobacterial strain used in the study was collected at the LaDuke hot spring in Montana, and was living in the underside of a thick mat that was so densely covered with microbes that only far-red wavelengths of light can penetrate to the bottom. The study suggests that it might be possible to introduce the ability to use far-red wavelengths in plants, though Bryant cautions that additional research will be necessary first.
“Our research already has shown that it would not be enough to insert a new far-red-light-absorbing pigment into a plant unless you also have the right protein scaffolds to bind it so that it will work efficiently,” he said. “In fact, it could be quite deleterious to just start sticking long-wavelength-absorbing chlorophylls into the photosynthetic apparatus.”
“We now have clearly established that photosynthesis can occur in far-red light, in a wavelength range where people previously did not think that oxygenic photosynthesis could take place, and we have provided details about many of the processes involved,” Bryant added. “Now there are a whole set of associated scientific questions that need to be answered about more of the details before we can begin to investigate any applications that may or may not be possible. Our research has opened up many new questions for basic scientific research.”
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