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Light-dependent multi-enzymatic synthesis of biofuels

Tenure Track Assistant Professor Bekir Engin Eser and Associate Professor Selin Kara. Photo By Jesper Bruun.
Tenure Track Assistant Professor Bekir Engin Eser and Associate Professor Selin Kara. Photo By Jesper Bruun.

Researchers have found an unusual, light-dependent enzyme in microalgae. A new project will use the enzyme in a system to produce drop-in fuels from waste oils and fats.

A grant of DKK 3 million (EUR 0.4 mill.) from the Novo Nordisk Foundation will kick-start a new research project at Aarhus University aiming to develop a system that, via completely natural processes, converts organic waste into sustainable biofuel we can pump directly into our cars.

It may sound too good to be true, but it’s not.

The focal point is a special light-dependent enzyme, which was first discovered about two years ago. The enzyme is found in microalgae and it has the particular characteristic that, with light as the only source of energy, it can decarboxylate fatty acids into alkanes, and thereby synthesize biofuel.

Compatible with society

“The project covers all stages of the process, from selection of the best mutant of the enzyme to development of the flow system itself, which, via photobiocatalysis, will convert organic waste oils and fats into different biofuels in a continuous flow,” says Tenure Track Assistant Professor Bekir Engin Eser from the Department of Engineering at Aarhus University.

These are the so-called drop-in biofuels, which are functionally equivalent to fossil fuels and are fully compatible with the existing petroleum infrastructure used in society.

In other words, this means that the sustainable biofuel extracted in this process can be used more or less directly in existing engines, so ordinary petrol and diesel vehicles can begin to run on a largely carbon- neutral green fuel.

Production has to be in a single, continuous flow in which waste stream is added at one end and, via enzymatic photobiocatalysis with the algae enzymes, is converted into fuel that comes out at the other end.

Mutation portfolio

However, before we get that far, a great many processes have to be linked together. At the moment, the enzyme produces alkanes of different lengths. The goal is to develop variants of the enzyme by protein engineering, so that we can adjust the individual production of alkanes to a kind of portfolio:

“So far, no one has tried to specialise the enzyme to create the product portfolio we want. For this reason, part of this project is to build a mutation library of the enzyme, so that, using different systems, we can make either diesel, petrol or jet-fuel in one process,” says Associate Professor Selin Kara, who is heading the project.

As biofuel based on waste oil and fat could become a significant part of the energy market of the future, the technology will have to be scaled up:

“The system has to be very, very efficient, because enormous amounts have to be produced if we are to get the industry interested in this transition,” says Associate Professor Selin Kara.


Project title

Light-dependent multi-enzymatic synthesis of biofuels from sustainable resources

Financial framework

DKK 3 million, Novo Nordisk Foundation

About the research section


Selin Kara

Associate professor