Photosynthesis is as ubiquitous as air itself, allowing plants to utilize sun’s energy for food production. As part of an ongoing research, scientists across the world are trying to develop artificial photosynthesis systems for quite some time now. What a team at the University of Copenhagen has accomplished, however, is something quite different. For the first time ever, researchers have achieved “reverse photosynthesis”, in which biomass is broken down to generate valuable chemicals and usable energy.

With the help of special molecules called chlorophyll, plants absorb light energy from the sun, converting it into chemical energy that in turn fuels the organisms’ day-to-day activities. This, along with water and carbon dioxide, is then used to produce carbohydrates, such as sugars. The process of photosynthesis actually helps build plant material, thus facilitating growth and development. In the current project, the scientists have discovered an entirely new natural process, which they are calling reverse photosynthesis. Speaking about the research, recently published in the Nature Communications journal, Claus Felby, a professor at the University of Copenhagen, said:

It has always been right beneath our noses, and yet no one has ever taken note: photosynthesis by way of the sun doesn’t just allow things to grow, the same principles can be applied to break plant matter down, allowing the release of chemical substances. In other words, direct sunlight drives chemical processes. The immense energy in solar light can be used so that processes can take place without additional energy inputs.

Like photosynthesis, the newly-found process relies on chlorophyll to trap sunlight. Unlike the former, however, it uses solar energy, coupled with a specific enzyme, to disintegrate biomass into simpler byproducts and energy. The breakthrough, the scientists believe, could drastically reduce the time needed to produce biofuels and other chemicals, while also decreasing pollution.

Central to the new process is a group of enzymes, called monooxygenases. Commonly used in the industrial production of biofuels, these naturally-occurring enzymes actually facilitate the breakdown of biomass into chemicals and usable energy. According to the researchers, their efficiency has been found to significantly increase when exposed to sunlight. Klaus Benedikt Møllers, a postdoctoral student at the university, said:

We use the term “reverse photosynthesis” because the enzymes use atmospheric oxygen and the Sun’s rays to break down and transform carbon bonds, in plants among other things, instead of building plants and producing oxygen as is typically understood with photosynthesis.

Although very little is actually known about reverse photosynthesis, the scientists believe that the process is used in nature, by certain species of fungi and bacteria, to access nutrients and sugars from plant material. As the team points out, the breakthrough could pave the way for faster and more energy-efficient production of biochemicals and biofuels, for such things as plastics. Thanks to the discovery, some reactions, that currently take up to 24 hours to complete, could easily be achieved in under 10 minutes with the help of sunlight. Felby added:

This is a game changer, one that could transform the industrial production of fuels and chemicals, thus serving to reduce pollution significantly.

Reverse photosynthesis, the researchers claim, helps disintegrate chemical bonds between carbon and hydrogen; a feat that could allow us to convert methane sourced from biogas plants into liquid fuels, like methanol, at normal conditions. In the petrochemicals industry, methanol is a valuable substance, which can be used as raw material in the production of a wide variety of chemicals and fuels.

Funded by the Danish Council for Independent Research, the project is the result of a collaboration between the University of Copenhagen and the Copenhagen Plant Science Center.

Source: University of Copenhagen











