A genetically engineered E. coli bacterium efficiently converts glucose into hydrocarbons, which in turn can be used to produce sustainable biofuels.

We are currently looking for ways to make our world more sustainable. Yet many do not want to give up the convenience of the car. An new study now shows that one does not have to exclude the other. Researchers have in fact combined the wonders of biology and chemistry by using peculiar microbes to convert glucose – a type of sugar – into olefins: a hydrocarbon and one of the components that make up gasoline.

E. coli bacteria

It sounds remarkable: converting sugar into hydrocarbons that are processed in gasoline. Yet that is exactly what scientists have achieved. How? In the study, the researchers fed glucose to genetically engineered E coli bacteria (which, by the way, pose no threat to human health). “These microbes are true sugar junkies, worse than children,” said researcher Zhen Wang. The sugar-consuming microbes were able to convert glucose into compounds known as 3-hydroxy fatty acids. While the bacteria feasted on the glucose, they simultaneously made those fatty acids. Using a catalyst, the researchers then removed the unwanted parts from the fatty acids, resulting in the end product: olefins.

Genetically engineered bacteria convert glucose into a fatty acid, which can then be converted into hydrocarbons called olefins. To grow such bacteria, scientists add the microbes to glasses filled with nutrients (the yellow substance). Image: Douglas Levere / University at Buffalo

It means that the researchers have found a method to make olefins directly from glucose. What are olefins? “Olefins are hydrocarbons (chemicals containing only carbon and hydrogen atoms) with double bonds (unsaturated bonds), Wang explains in an interview with Scientias.nl from. “They are found in small amounts in gasoline and other petroleum-derived fuels. In addition, they are used as precursors to make polymers. Most importantly, our produced olefins could potentially be incorporated into gasoline to power cars in the future.”


What’s so interesting about the new method is that the olefins the researchers produced were made from glucose instead of crude oil. “The glucose comes from the air because plants and algae convert carbon dioxide into sugars through photosynthesis,” Wang explains. “So when we use the new olefins as fuel, we’re essentially returning carbon dioxide to the air. This means that the cycle is CO2 neutral. Crude oil, on the other hand, is formed over hundreds of millions of years from the remains of ancient plants and algae. When using fuels from crude oil, an enormous amount of CO2 is released in a very short time, which leads to the greenhouse effect. In contrast, the olefins we have produced are very sustainable.”


Although the researchers have shown that it is technically possible to make olefins from glucose, the method still needs considerable refinement. For example, it still needs to be mapped out how much energy it costs to manufacture the olefins. “We are also working on increasing conversion efficiency,” Wang says. “For example, the conversion of glucose to olefins needs to be much more optimized before it can be used for commercial applications.” For example, it currently takes 100 glucose molecules to produce about 8 olefin molecules. The goal now is to improve that ratio. “Ideal would be to produce about 42-44 olefin molecules per 100 glucose molecules,” Wang says. “That’s the theoretical limit.” One way to do that is to somehow get the E. coli bacteria to produce more 3-hydroxy fatty acids for every gram of glucose consumed.

However, if we succeed in optimizing the process, it could be a major step in our efforts to make sustainable and environmentally friendly biofuels. “The study shows that it is technically feasible to get gasoline-like fuels from renewable sources, so that we are no longer so dependent on crude oil,” emphasizes Wang. “Nature really gives us countless opportunities to solve a problem and gives us the enzymes we long for as a gift. Obtaining fuels from renewable sources will then help us protect the environment and leave the world a better place for generations to come.”