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Biological switch could improve biofuel production by algae

Scientists have discovered a biological switch in blue-green algae that reacts to light and changes how electrons are transported within the cells.

Scientists have discovered a biological switch in blue-green algae that reacts to light and changes how electrons are transported within the cells. The new findings could help in engineering algae for improved biofuel production. The results of the research were published on July 10, 2012 in Proceedings of the National Academy of Sciences.

Blue-green algae, also known as cyanobacteria, are well known for their explosive growth when given the right combination of light, nutrients and warm water. Due in part to their high growth rate, their ability to use wastewater as a source for nutrients and their ability to grow without competing with arable land used to grow food, cyanobacteria and other types of algae have become a prime target for biofuel production.

Lack of light is often a major constraint in algae biofuel production systems because algae need light to photosynthesize. Attempts to increase the amount of light delivered to algae in bioreactors typically involve the use of energy-demanding mixing systems or smaller and more expensive growth chambers.

Alternatively, scientists could try to improve the way that algae grow under low light conditions. But first, they need to more fully understand how the biological molecules within cells respond to light.

Cyanobacteria displaying a green fluorescent tag. Image credit: Queen Mary, University of London.

To examine how cyanobacterial cells respond to light, scientists attached a green fluorescent protein tag to two key respiratory complexes in the species Synechococcus elongatus. Then, they exposed the cyanobacterial cells to either low light or moderate light conditions in the laboratory and tracked changes in the cells by viewing the cells under a microscope.

The scientists discovered that brighter light caused the respiratory complexes to redistribute throughout the cells from discrete patches into more evenly distributed locations. The redistribution of respiratory complexes appeared to be triggered by changes in the redox state of an electron carrier close to plastiquinone, and resulted in a major increase in the probability that electrons would be transferred to photosystem I, an integral component of the photosynthetic complex shown in the diagram below.

The research was carried out by seven scientists from Queen Mary, University of London, the Imperial College London and the University College London.

Flow of electrons (light blue circles) inside a cell during photosynthesis. Image credit: Wikimedia Commons.

Conrad Mullineaux, who is a Professor of Microbiology at Queen Mary, University of London and co-author of the new paper, commented on the findings in a press release. He said:

Any organism that breathes or photosynthesizes depends on tiny electrical circuits operating within biological membranes. We are trying to find out what controls these circuits: what makes the electrons take the routes that they do, and what switches are available to send the electrons to other destinations?

He commented on the new findings further in an interview with Ecoimagination:

It’s rather like a familiar electrical switch. You press on it to change the position of the wires, and thereby change what the electrons do. At this state, we’re just trying to understand what’s happening in the cell. But the potential is there to exploit the knowledge for biofuel production.

Bottom line: Scientists have discovered a biological switch in cyanobacteria that reacts to light and changes how electrons are transported within the cells. The new findings could help in engineering blue-green algae for improved biofuel production. The results of the research were published on July 10, 2012 in Proceedings of the National Academy of Sciences.

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