Imagine a world where instead of creating CO2 as an emission from burning fuels, you could make fuels from the emissions, the CO2.
And could do so in a way that bypasses the production of biomass and the extraction of fermentable sugars — thereby getting around the energy-intensity of making biomass and then destroying it.
And could do so in a way that bypasses the known limitations of photosynthesis — where no more than 5% of solar energy is captured in the form of biomass.
Broadly speaking, this is the goal of a series of teams researching electrofuels — under a series of ARPA-E grants dating back to 2010 and broadly expiring this year. One of those projects united teams from the University of Georgia and North Carolina State. The project for “Liquid Fuel from Heat-Loving Microorganisms,” won a $2.4 million ARPA-E grant in that 2010 round.
This week in the Proceedings of the National Academy of Sciences, a team from both universities led by Michael Adams has revealed that they have engineered Pyrococcus furiosus to make 3-hydroxypropionic acid using hydrogen gas, and CO2.
Using no sunlight, no biomass, no sugars.
Since 3-hydroxypropionic acid rarely comes up at cocktail parties — we’ll describe it as one of the DOE’s top 12 value added building-block chemicals from it’s 2004 survey, the same report that stimulated, for example, the rush to make succinic, levulinic and glucaric acids as well as glycerol. More importantly, if you can make that today — you can make fuels down the line.
OK, what’s Pyrococcus furiosus?
I know, Pyrococcus furiosus sounds like a Harry Potter spell, right up there with “wingardium leviosa.”
Actually, it may feel a little magical, at the end of the day — at least the claims that are now being advanced as to this microvarmint’s skills. But it’s a relatively well-known microorganism found in the vicinity of underwater geothermal vents or volcanoes. It’s one of the archaea — a group of one-celled critters long thought to be a subset of bacteria, but which in recent years have been shunted off to a domain in the taxonomy of life all their own.
This little archaeon is one for the books — whose name translates from a mash-up of Medieval Latin and Classical Greek as “raging fireball” — known for having a preferred temperature of 100 degrees celsius.
P. furiosus was originally isolated anaerobically from geothermally heated marine sediments with temperatures between 194 °F and 212 °F collected at the beach of Porto Levante, Vulcano Island, about 16 miles north of Sicily. It’s the island from which the word “volcano” takes its name.
Yep, some like it hot. Real hot.
It’s other amazing property is that it doesn’t require sunlight for energy. It’s limitation? Historically, P. furiosus fed on carbohydrates — which put it squarely back into the biomass cycle, because plants make carbs using sunlight — and if you are processing carbs, you are dependent on their formation even if you don’t make them as an intermediate product yourself.
Enter our team from the University of Georgia and North Carolina State, who have inserted a clutch of DNA borrowed from another archaeon, Metallosphaera sedula, originally also discovered in the volcanic fields of Italy. Which have conferred on the newly-improved P. furiosus the ability to use carbon dioxide in the presence of hydrogen gas to directly generate the afore-mentioned 3-hydroxypropionic acid.
As the research team reports:
“The engineered P. furiosus strain is able to use hydrogen gas and incorporate carbon dioxide into 3-hydroxypropionic acid, one of the top 12 industrial chemical building blocks. The reaction can be accomplished by cell-free extracts and by whole cells of the recombinant P. furiosus strain. Moreover, it is carried out some 30°C below the optimal growth temperature of the organism in conditions that support only minimal growth but maintain sufficient metabolic activity to sustain the production of 3-hydroxypropionate. The approach described here can be expanded to produce important organic chemicals, all through biological activation of carbon dioxide.”
What does it mean?
Well, consider the pathways being pursued by some of the very hottest companies in bioenergy. There’s been huge admiration for Solazyme — stemming from its production of tailored renewable oils using dark fermentation performed by algae — thereby bypassing problems experienced growing algae at scale in open ponds. Here, like Solazyme, the microorganisms do not use sunlight — but in the case of P. furiosus, the organism is directly utilizing CO2 instead of munching sugar.
In the case of hot companies like Joule and Proterro — which have processes all their own, using modified cyanobacteria, to make fuels and chemicals (in the case of Joule) or sugars (in the case of Proterro) from sunlight, CO2 and water. With P. furiosus, no need for sunlight — dark fermentaiton equipment can be used, instead of the need to comb the planet looking for good solar insolation.
In some ways, the organisms are similar to those used by INEOS Bio, Coskata and LanzaTech, which work with gas fermentation. Though, to date, only LanzaTech has indicated that it can work with CO2 instead of a syntheis gas produced either from biomass or natural gas. In this case, the other differentiating factor is to a great extent in the temperatures the organism prefers. As many readers know — once the target chemical or fuel is in the broth, there’s often a distillation step to separate, for example, alcohols from water. Working with organisms that can tolerate great amount of heat cuts down on the energy required for distillation — because you don’t have to heat and cool the broth to such an extent.
Plus, thermophiles, because of the temperatures they live at and the food they eat, are rarely troubled by competitors, pests, or parasites in the same way that conventional fermentation systems are, which operate at lower temperatures and have tasty sugars swilling around in the broth.
“Basically, what we have done is create a microorganism that does with carbon dioxide exactly what plants do-absorb it and generate something useful,” Michael Adams told UGA Today. Adams is a member of UGA’s Bioenergy Systems Research Institute, Georgia Power professor of biotechnology and Distinguished Research Professor of biochemistry and molecular biology in the Franklin College of Arts and Sciences.
“What this discovery means is that we can take carbon dioxide directly from the atmosphere and turn it into useful products like fuels and chemicals without having to go through the inefficient process of growing plants and extracting sugars from biomass.”
The underlying Electrofuels Project
NC State is working with the University of Georgia to create electrofuels from primitive organisms called extremophiles that evolved before photosynthetic organisms and live in extreme, hot water environments with temperatures ranging from 167-212 degrees Fahrenheit. The team is genetically engineering these microorganisms so they can use hydrogen to turn carbon dioxide directly into alcohol-based fuels.
High temperatures are required to distill the biofuels from the water where the organisms live, but the heat-tolerant organisms will continue to thrive even as the biofuels are being distilled–making the fuel-production process more efficient. The microorganisms don’t require light, so they can be grown anywhere—inside a dark reactor or even in an underground facility.
Where is the team in scale-up?
It’s a lab-scale right now – long way from the market, my friends. “It’s an important first step that has great promise as an efficient and cost-effective method of producing fuels,” Adams told UGA Today. “In the future we will refine the process and begin testing it on larger scales.”
READ MORE. ARPA-E: Liquid fuel from heat-loving microorganisms.
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