Synechococcus brewing in a bioreactor. Credit: Pacific Northwest National Laboratory

Synechococcus brewing in a bioreactor. Credit: Pacific Northwest National Laboratory

Phys.org reports that scientists from the University of Southampton have reengineered the fundamental process of photosynthesis to power useful chemical reactions that could be used to produce biofuels, pharmaceuticals and fine chemicals.

Photosynthesis in plants and algae consists of two reactions, the light-reactions absorb light energy from the sun and use this to split water (H2O) into electrons, protons and oxygen, and the dark-reactions, which use the electrons and protons from the light reactions to “fix” CO2 from the atmosphere into simple sugars that are the basis of the food chain. Importantly, the light reactions have a much higher capacity than the dark reactions resulting in much of the absorbed light energy being wasted as heat rather than being used to “fix” CO2.

“In our study, we used synthetic biology methods to engineer an additional enzyme in-between the light-reactions and before the dark-reactions,” said co-author Dr. Adokiye Berepiki, a Postdoctoral Research Fellow from Ocean and Earth Sciences at the University of Southampton. “We have therefore ‘rewired’ photosynthesis such that more absorbed light is used to power useful chemical reactions. This study therefore represents an innovation whereby a range of additional valuable chemical reactions can be powered by the sun in plants and algae.”

In the study, published in ACS Synthetic Biology, the “wasted” electrons were rewired to degrade the widespread environmental pollutant atrazine (an herbicide used in agriculture). Atrazine was banned from the EU over 20 years ago but is still one of the most prevalent pesticides in groundwater. The photosynthetic algae designed by the researchers may be used in the efficient bioremediation of such polluted wastewater areas.

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