Hiding in plain sight: The common bacterium that could revolutionize our response to climate change

Replacing petroleum-based production with sustainable alternatives is no small feat. The shift depends on companies abandoning established infrastructure and embracing new technologies, and presents challenges in terms of food security, soil health, storage and safety. But a recent breakthrough discovery in a common bacterium could spark meaningful change. 

The bacterium is called Desulfovibrio desulfuricans, and it’s at the heart of what IE University microbiologist Dr. Irene Sánchez-Andrea has identified as the seventh CO₂ fixation pathway. While other microorganisms require organic carbon sources to survive, Dr. Sánchez-Andrea discovered that this bacterium can grow just on CO₂ and hydrogen - essentially eating greenhouse gases.

The implications of this extend far beyond the lab. Engineered microbial systems based on this pathway could theoretically produce everything from biofuels to pharmaceuticals directly from atmospheric CO₂, offering not just a carbon-neutral but a carbon-negative alternative to fossil fuels. It’s also one of the most energy-efficient pathways discovered to date, which means that it could be easier and more economical to scale.

The environmental crisis as it currently stands

Of the many challenges facing the global response to climate change, arguably the biggest obstacle is economic. Because the platforms for fuel-based production are so well established, there’s little to no economic incentive for sectors and companies to adapt or innovate. It simply makes more financial sense to continue with the status quo.

“Obviously, policy has a big role to play here,” says Dr. Sánchez-Andrea. “If governments put concrete steps in place to mitigate climate change in the form of legal and regulatory requirements, the private sector will have to follow. But until companies are forced to invest in new infrastructure, we’re not likely to see the adoption we need.” 

The scale of the challenge is another factor. Current CO₂ levels and climate projections demand CO₂ removal technologies capable of operating at previously unimagined levels. This means that we need to experiment with and develop as many technologies as possible. To have a net positive effect, numerous innovations will have to be deployed at scale all over the world - CO₂ fixation among them. 

And finally, we need to acknowledge - and act on - the fact that our endless cycle of producing items only to throw them away, again and again and again, is the very definition of unsustainable. Implementing a circular economy shouldn’t be aspirational; it should be imperative. But change will not come fast. Nor will it be easy, of course.

The search for alternatives

The hunt for sustainable alternatives to petroleum-based fuels is nothing new. The environmental impetus, academic research and commercial response have existed for decades. In this time, solar, wind and hydroelectric power have matured from experimental technologies into major energy sources; hydrogen fuel cells have gained traction; and biotechnology options like algae cultivation, biogas and biofuels have come to the fore.

None of these solutions has fully displaced our dependence on fossil fuels, however, and each has presented its own set of challenges. Biomass-based materials, for example, offer a more sustainable alternative to fossil fuels since plants absorb CO₂ as they grow. But converting agricultural crops into fuel and industrial materials puts them in direct competition with food production, and intensive biomass cultivation accelerates erosion and degrades the quality of soils. This is a problem because healthy soils are one of nature’s most important carbon sinks, storing massive amounts of CO₂. 

“We can’t solve one problem by creating two more,” explains Dr. Sánchez-Andrea. “We have to find alternatives to petroleum, but we can’t do so while compromising food security and environmental health.” She adds that we shouldn’t dismiss these options entirely, but rather encourage the pursuit of other, better alternatives.

This thought process turned Dr. Sánchez-Andrea’s attention to bacteria that feed directly on CO₂ from the atmosphere. These wouldn’t require agricultural land or crops, nor would they compete with food production. As she followed this train of thought, what started off as a side project alongside her main research ultimately led to a pivotal breakthrough. 

The seventh pathway 

In October 2020, Dr. Sánchez-Andrea and her colleagues released the results of three years of research in their paper, “The reductive glycine pathway allows autotrophic growth of Desulfovibrio desulfuricans,” published in Nature Communications. Their research revealed the existence of a seventh CO₂ fixation pathway and cast a common bacterium in a whole new light.

The journey began when Dr. Sánchez-Andrea started to explore D. desulfuricans in more detail. A widely studied bacterium, D. desulfuricans is one of the most well-known sulfate-reducing organisms ever isolated and has been a laboratory staple for decades. Earlier research presumed that it needed organic carbon to grow - but Dr. Sánchez-Andrea found that the bacteria appeared in places where organic carbon didn’t exist.

The process was slow initially. While her experiments showed some turbidity, they didn’t offer definitive insight, and even the cell growth results felt unreliable. The transfer process also involved such small quantities that it was difficult to come to any definitive conclusions. When Dr. Sánchez-Andrea saw that she was fixing CO₂, she sequenced the genome and checked for the six known pathways. This result delivered nothing. None of the six known pathways was complete. 

“This brought me two main hypotheses,” she explains. “A: I have grown this bacteria on CO₂ because I have some organic matter in my culture. Or B: It is growing on CO₂, and that is a novel path that needs to be described.” After hundreds of controls, Dr. Sánchez-Andrea concluded that the latter was correct. Her subsequent RNA sequencing process confirmed this, providing a list of potential genes that were different from the other conditions.

The result, in technical terms, is that Dr. Sánchez-Andrea proved that she could grow D. desulfuricans autotrophically. And her genomic, transcriptomic, proteomic and metabolomic analyses showed that it assimilates CO₂ via the reductive glycine pathway—a previously proposed but until now unconfirmed seventh fixation pathway.

In practical terms, she’d found that an everyday bacterium could eat air pollution and turn it into useful fuels and chemicals.

What made this pathway even more exciting, however, was that it proved to be one of the most energy-efficient pathways yet discovered, with just one to two ATP molecules consumed per pyruvate. This is likely to make it more economically viable, easier to scale and more likely to be applied in the real world.

Beyond the lab 

So, what are the commercial applications of this discovery, and how could it benefit global sustainability efforts?

The seventh pathway could be applied in two main ways: first, through its natural capabilities and second, through synthetic biology.

In its natural state, D. desulfuricans already produces several valuable materials. It generates biomass that could serve as a protein source for alternative foods, including lab-grown meat substitutes. And it naturally produces a range of amino acids and organic compounds like acetate and formate, which have many established industrial uses.

If we look at its synthetic applications, the possibilities are fascinating. Scientists could insert specific genes to reprogram the bacterium’s metabolism, turning it into a factory of high-value compounds. This approach is already delivering results across the biotechnology industry, where other CO₂ fixation pathways are producing pharmaceutical compounds, antioxidants for cosmetics and other specialty chemicals.

One especially promising application of D. desulfuricans involves its natural production of formate, which researchers are increasingly interested in as a potential alternative to hydrogen in the green economy transition. While hydrogen and formate are chemically similar, formate’s liquid state makes it easier to transport and safer to store than hydrogen, a gas.

At this stage, commercial scaling and applications for this pathway haven’t yet come into play. When they do, they’re likely to be a source of interest to a huge range of industries—particularly energy-based companies and the chemical sector. The seventh pathway is also being adopted by genetic engineering researchers, who are experimenting with mixed microbial communities that expand the range of possible products even further.

Dr. Sánchez-Andrea’s work was undertaken in collaboration with researchers at Wageningen University & Research in the Netherlands, and their input-at early and key moments throughout the project-has been invaluable. Other partners included the Max Planck Institute. Commercial funding is the next inevitable step.

An endless quest

Of course, as we look to climate change mitigation and alternative sources of fuel, this isn’t the only solution—and it shouldn’t be viewed in isolation. The seventh pathway is one of many theories being explored in this niche field of sustainability research, and all are worth interrogating. We can only find the solution (or solutions) to the complex environmental, economic and social challenges posed by climate change if we have as many options as possible on the table.

“For those of us working in sustainability, it’s clear that it’s important to innovate,” Dr. Sánchez-Andrea says. “Maybe from the countless solutions we uncover, only a handful will ultimately prove useful. But having a variety available will mean that we’re better able to choose and adapt to our current problems and those we are yet to encounter. Maybe this pathway will prove critical down the line, or maybe something else will turn out to be more relevant or valuable. Regardless, we have to continue searching for answers.”

This doesn’t mean the answers need to come in a hurry (which might be paradoxical, given the urgency of the environmental crisis). Dr. Sánchez-Andrea’s research experience gave her a new perspective on the importance of patience and perseverance when looking for innovative breakthroughs.

“This project was well timed,” she says. “I wasn’t under a huge amount of time pressure and was able to take things slowly. I typically work in extreme environments, where growth and change are often gradual. I’ve learnt to be patient. When I wasn’t initially sure that there was any growth, I waited. I kept trying and transferring. I leaned into my theories and gave the process a chance.”

There was every chance that her perseverance wouldn’t be rewarded. Any scientist can tell you that every experiment carries the risk of delivering nothing. But in this case, patience yielded results-and the prize was a new piece of the sustainability puzzle.

Big-picture thinking

As we put all the pieces together, there is a bigger picture that we need to keep in mind.

“We’re worrying about the balance of CO₂,” Dr. Sánchez-Andrea explains, “when in fact we should be setting our sights higher. Yes, achieving carbon neutrality should certainly be our first step. If we don’t stop accumulating CO₂, the impacts of climate change will continue to worsen. But we have to settle our carbon debt as well.”

Historical CO₂ emissions have already warmed the planet to approximately 1.1ºC above pre-industrial levels. This means that even achieving carbon neutrality only stops us from worsening an already poor situation. In order to make a material impact, we need to go carbon negative and undo the damage we’ve already done. We need to actively remove CO₂ from the atmosphere.

It’s an idealistic scenario, and as we race closer towards 1.5ºC, rather than away from it, it feels increasingly impossible. But D. desulfuricans’ ability to produce everything from biofuels to pharmaceuticals directly from atmospheric CO₂ is proof that carbon-negative solutions do exist. A regenerative course of action is possible-and worth pursuing.

How we combine and scale solutions to meet our global challenges is not yet clear. But at IE University, researchers like Dr. Sánchez-Andrea are working on the breakthroughs that could provide the key to a more sustainable future.