Photosynthesis is central to life on Earth, using energy from sunlight to make the oxygen we breathe and the food we eat. However, photosynthesis is only a few per cent efficient when you compare the energy of the sunlight that reaches a plant with the energy that ends up in the biomolecules of the plant (and even less in the parts we eat). Moreover, an analysis of plant breeding efforts over the last few decades has shown that many plant traits have already reached a state that is close to optimal for agricultural use, while photosynthesis clearly has a lot of room for improvement.
The PhotoRedesign project therefore aims to improve the efficiency of photosynthesis, and more specifically the light reactions of photosynthesis that capture light and convert the captured light energy into molecules that can then be used to convert carbon dioxide from the atmosphere into organic biomolecules. In fact, nature has invented several types of organisms capable of photosynthesis. Because they all go back to a common ancestor, these organisms are still genetically compatible, meaning that their genes also work in the other organisms. We chose three very distantly related organisms that can use very different parts of the sun's light for photosynthesis: cyanobacteria, which are blue-green, plants, which are green, and purple bacteria, which are purple. As mentioned earlier, their different colours indicate that they can use very different parts of the sun's light for photosynthesis.
Our goal is to combine the different light-harvesting components of these three organisms. Ideally, this will produce an organism that is black because it uses all parts of sunlight. We are using the cyanobacterium Synechocystis as a test laboratory because it is easily accessible for genetic manipulation.
The creation of such a black cyanobacterium would in itself be a breakthrough in the field of photosynthesis enhancement research. Cyanobacteria are important model organisms for biotechnological applications, and such black cyanobacteria could provide the basis for improved production of biofuels and other valuable compounds. Equally important, the results obtained in cyanobacteria can be transferred to the plants that provide our food. To this end, the cyanobacterium can be used as a test laboratory for enhanced photosynthesis, which can then be replicated in its optimised form in plants.
