Two of the great challenges that humanity faces are, on the one hand, to produce clean energy, and on the other, to limit carbon dioxide emissions into the atmosphere to slow down climate change. Well, plants are capable of doing both through photosynthesis , a process by which they obtain the sugars that give them energy using sunlight, water and carbon dioxide as ingredients, which is why they fix carbon in parallel.
Is it possible to imitate this process in an artificial and more efficient way to produce clean energy and fix carbon? That is the goal, still a long way off, that a team of scientists from the Max Planck Institute for Terrestrial Microbiology (Germany) aims to achieve, which has developed a kind of artificial chloroplasts – organelles of plants in which photosynthesis takes place – capable of convert carbon dioxide to sugar using sunlight and through a chemical process designed in the laboratory.
Laboratory photosynthesis
To convert CO2 into sugar, plants can use different metabolic pathways involving enzymes capable of harnessing solar or chemical energy . In 2016, the team of researchers designed a new way to perform this function in the laboratory. They called it the ‘ CETCH cycle ‘, and it consists of a complicated network of enzymes that manages to be around 20% more efficient than natural photosynthesis pathways .
The next step, which is described in an article recently published in the journal Science , was to assemble this cycle with the rest of the machinery of a living cell. To do this, the researchers used spinach cell chloroplasts and extracted the thylakoids, which are a kind of flattened sachets in which light is captured. The result: a kind of artificial chloroplasts in which the thylakoids obtained from spinach collect energy from the sun and subsequently, the enzymes of the synthetic CETCH cycle use this energy to convert carbon dioxide into glycolate , a molecule that is part of the photorespiratory route and that can also be used as raw material to make organic products.
Possible applications: drug production and CO2 fixation
Thanks to advances in the field of synthetic biology, microbes can now be designed to produce useful molecules in industry, although living cells have certain limits: you cannot synthesize anything or with the desired efficiency. According to the authors of this work, artificial chloroplasts could produce molecules that living cells are unable to obtain.
Another possibility would be the use of these mini reactors to trap carbon dioxide and contribute to the mitigation of climate change, but there are enough limitations to implement this technology on a large scale. One of them, for example, is that growing spinach and extracting the components from its cells is a slow process. One option would be, according to the authors, to develop artificial systems that allow the spinach membranes to be replaced.
“In the long term, these life-like systems could be applied to virtually all areas of technology, including materials science, biotechnology and medicine, ” explains Tobias Erb, one of the authors. “We are only at the beginning of this one. exciting road ”.
Reference: Miller et al. 2020. Light-powered CO2 fixation in a chloroplast mimic with natural and synthetic parts. Science 368, 649–654
