Scientists create bacteria that can eat carbon dioxide

Carbon-neutral is a goal of scientists around the world - the aim to produce what we need without increasing the greenhouse gases which are changing the climate.

Scientists from the Weizmann Institute of Science in Israel believe they may be at the earliest stages of being able to do that.

Normally E.coli feeds on sugar and emits CO2 gas (carbon dioxide).

"So we engineered those bacteria to use CO2 as their feedstock instead of sugars and this was the first time that in science such a transformation took place, of converting organism that is capable of only consuming sugar into an organism that consumes CO2 in order to produce its biomass," said researcher Shmuel Gleizer.

To get the E.coli to swap its preferred sugar diet for the gas, scientists took a genetically modified strain of E.coli and fed successive generations of it big concentrations of CO2 and minute amounts of sugar.

Researchers say the amount of CO2 they were fed was 250 times the concentration of carbon dioxide found in Earth's atmosphere.

The idea of this was that the bacteria starved of sugar would evolve and adapt to its new carbon dioxide diet. The E.coli that were able to evolve were the most successful.

"We set up a special evolutionary regime for this bacteria," said Gleizer. "We basically wanted to give them just a little bit of sugar to enable initial growth and then keep them for a long period in starvation state for sugar, but on the other hand constantly provide them with plenty of CO2, and plenty of a molecule called formate which serves as the energy source for this bacteria. 

"And then after a few months of evolving the bacteria in such conditions we were able to isolate bacteria that no longer needed sugar at all in order to survive."

The E.coli bacteria is found in warm-blooded organisms including humans and is the preferred bacteria for scientists exploring genetics and biotechnology. 

It is easy to reproduce in laboratories and has been extensively studied for over 60 years. Because it's easily found and reproduced, its is used in production of vaccines and biofuels.

"Now that we can feed it with CO2 it gives hope that gradually the bio-technology industry can switch to CO2 being the main feedstock for the bacteria, and the energy for the bacteria could be provided, with future research, from renewable sources that don't involve CO2 at all.

"This could be progressed even more into actual solutions that will be used both in the industry but also in agriculture to create more food and also try to tackle greenhouse gas emissions."

The process isn't yet complete - while the E.coli does consume CO2, researchers say overall it still produces more carbon dioxide than it consumes so it is not yet carbon-neutral. 

The study has been published in the journal Cell.