Researchers have mapped the genes of a remarkable bacterium that consumes carbon dioxide (CO₂) and turns it into useful products. Perhaps they can be used to make plastic, medicine and food while also removing CO₂ from the atmosphere, according to the researchers.
A bacterium called Cupriavidus necator has caught the attention of several researchers because it consumes CO₂ and, in the process, could produce something that is useful to people.
These microbes could produce plastic, biofuels, food or even medicines – while drawing CO₂ out of the atmosphere and helping to restore the global climate balance.
For decades, C. necator sat almost forgotten in a laboratory cellar in Germany. Now scientists have dusted them off and sequenced their entire genome. This shows that some strains have traits that could make them miniature climate-friendly factories.
“In the future, we will need to find new production methods for everything from chemicals to food, and bacteria are promising in this context. These bacteria are especially promising because, in addition to being able to be manipulated to produce useful industrial products, they absorb CO2. This is positive for a climate-friendly type of production,” explains a researcher behind the study, Stefano Donati, Senior Researcher, Novo Nordisk Foundation Centre for Biosustainability, Technical University of Denmark, Kongens Lyngby.
The research has been published in Microbial Biotechnology.
From basement laboratory to climate hope
C. necator was discovered in Germany in the 1960s.
At the time, it aroused the interest of researchers because it can both absorb CO₂ and use hydrogen as fuel to drive an entire chemical process.
Plants can also absorb CO₂ through photosynthesis, but they use sunlight as their energy source. C. necator draws its energy from chemistry.
Since C. necator uses energy from hydrogen to convert CO₂ into potentially useful products, this opens opportunities for growing it in tanks.
In contrast, bacteria that depend on sunlight would be difficult to cultivate on an industrial scale – but supplying hydrogen makes it feasible.
“If we can exploit C. necator in industry, we can make all these useful products with a net negative consumption of CO2. This has future prospects,” says Stefano Donati.
44 potential bacterial strains reveal hidden strengths
However, C. necator is not just one strain of bacteria. Researchers have found several strains in nature or developed them in the laboratory.
The challenge has been that researchers have never had a comprehensive overview of the genetic differences between the strains – and therefore did not know which ones were most promising. The researchers did this in this study.
Stefano Donati and colleagues collected all the available genetic information they could find about C. necator online and then performed a full genetic readout of the bacterial strains that had been sent from Germany.
In the end, they examined the genomes of 44 strains, but after thorough review, only 22 remained as genuine C. necator. The researchers used these to map both their capabilities and the differences between them.
“We now want to determine how the strains of C. necator can be used. To do that, we first need to delve deeply into their genes – and that is what we did in this study. It felt almost like digging for fossils – except that the fossils were hidden in the bacteria,” notes Stefano Donati.
Only a few can produce energy from hydrogen
The study found 22 strains of C. necator. Some strains, which originally came from Germany, Japan and the United States, were so similar that they were not different strains but the same strain. This also means that they originally came from the same source.
In contrast, some of the strains differed more than the researchers had thought.
The biggest surprise was that only a handful of strains carried the full genetic toolkit to use hydrogen as fuel for turning CO₂ into biomass. Most were missing key pieces of the machinery. Nevertheless, all strains could convert CO₂.
“This changes our entire view of C. necator. Some strains can use hydrogen to convert CO₂ – but far from all of them. This has major implications for how we will work with them in the future,” says Stefano Donati.
The researchers also found that all strains can produce polymers for bioplastics, but three stood out in particular: ATCC 25207, TA06 and 1978. They have different genetic characteristics that make them promising candidates for future industrial use.
“By reading the genes, we can identify which strains are most suitable. The study gives us an overview of what these C. necator can do and which of them are best at it. This paves the way for further research. We are currently investigating which C. necator will be most suitable for industrial purposes,” concludes Stefano Donati.
