The future of making plants grow without natural photosynthesis


Tam-Tri Le, Phenikaa University (Hanoi, Vietnam)
https://orcid.org/0000-0003-3384-4827

October 4, 2022

Seeing the energizing beauty of plants among the green landscape on Earth, since the early days of civilization, humans have always wanted to gain the power of photosynthesis. Even more ambitiously, we are now seriously thinking about developing extraterrestrial photosynthesis technologies. For example, scientists have proposed a photosynthesis pathway using lunar soil as catalysts to turn water and CO2 into fuel and O2 with solar energy [1].

But before taking the matter to space, scientists have been trying to find different ways to enhance the efficiency of biological photosynthesis to boost agricultural productivity by supporting natural photosynthetic machinery [2]. Plants’ energy conversion efficiency of photosynthesis in typical conditions is only about 1%, much less than the theoretical maximum.

Many aspects of the process can be improved by artificial means. For example, the highly abundant pigment chlorophyll in plants is only efficient in capturing red and blue light (which gives leaves the typical green color). Regarding the weak absorption region of the spectrum, conjugated polymers can work as antenna pigments for increasing the photosynthetically active radiation range [3].

As it is suggested that photovoltaic-driven electrolysis can be more efficient than natural photosynthesis [4], scientists have been trying even more radical approaches. In a new study published in Nature Food, the researchers found a way to completely bypass biological photosynthesis to produce plant- or algae-based biomass [5]. Electrolysis using electricity generated by photovoltaics converts CO2 and H2O into O2 and acetate. Food-producing organisms such as algae and plants then consume acetate for growth, which can happen in the dark, completely independent of natural photosynthesis. The study also employed a state-of-the-art two-step electrocatalytic process that is highly energy efficient compared to typical solar-to-biomass food production processes. For example, their yeast production efficiency is 18 times higher than normal cultivation using sugar from corn.



Figure
: A combined electrochemical–biological system for the production of food from CO2 [5] (CC BY 4.0); https://media.springernature.com/lw685/springer-static/image/art%3A10.1038%2Fs43016-022-00530-x/MediaObjects/43016_2022_530_Fig1_HTML.png

But this technology does not necessarily exclude natural photosynthesis. Besides allowing for farming in the dark, the method can be used to supply acetate to normally grown crops to boost their yields as well. As this is only among the first steps in a big ambition, further research, such as in genetic engineering, can help make popular crops more compatible with utilizing acetate (or future technologies’ alternatives).

It seems that humanity’s dream of harnessing the power of light is getting closer and closer to reality. The implications of these new scientific advancements provoke contemplations about the future. If we can fundamentally change the basic energy-dependent mechanisms of information processing systems [6], will the ecosphere become more human-dependent, or will it be limited by other natural constraints instead?

References

[1] Yao Y, et al. (2022). Extraterrestrial photosynthesis by Chang’E-5 lunar soil. Joule, 6(5), 1008–1014.

[2] Leister D. (2022). Enhancing the light reactions of photosynthesis: Strategies, controversies, and perspectives. Molecular Plant.

[3] Zhou X, et al. (2022). Organic Semiconductor–Organism Interfaces for Augmenting Natural and Artificial Photosynthesis. Accounts of Chemical Research, 55(2), 156–170.

[4] Blankenship RE, (2011). Comparing photosynthetic and photovoltaic efficiencies and recognizing the potential for improvement. Science, 332(6031), 805–809.

[5] Hann EC, et al. (2022). A hybrid inorganic–biological artificial photosynthesis system for energy-efficient food production. Nature Food, 3(6), 461–471.

[6] Vuong QH. (2022). Mindsponge Theory. AISDL.