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mercial plant to open in 2018, promising up to 10,000 barrels of ‘green crude oil’ per day. But algae also typically require large growing areas, and are harvested and processed in batches to remove their valuable oils, which significantly increases costs.

To overcome these constraints, some com-panies are turning to simpler organisms. “Cyanobacteria make a good microbiological factory for chemical and fuel production—they’re the most energy-efficient organisms on Earth,” says Dannenberg. These photosynthetic bacteria naturally convert CO2 into pyruvate, a precursor to various valuable chemicals. Cyanobacteria excrete these chemicals as they grow inside bioreactors, allowing manufactur-ers to extract the products continuously with-out harvesting the microbes.

Joule Unlimited of Bedford, Massachusetts, has taken genes from bacterial DNA sequences in the public database GenBank to optimise the industrial fitness of cyano-bacteria. The company modified strains of Synechococcus to overexpress the pyruvate decarboxylase and alcohol dehydrogenase enzymes that convert pyruvate into ethanol. The organisms can incorporate one or more of these genes to produce different catalysts, each optimized to convert CO2 into fuels of chemicals. The company aims to begin com-mercial production in 2018. Rival company Algenol in Fort Myers, Florida, is already using a cyanobacterium host cell carrying a genetically enhanced plasmid encoding both enzymes in the ethanol pathway to produce over 8,000 gallons of ethanol per acre per year at a demonstration facility in New Mexico, more than ten times the typical yield of a corn ethanol producer.

Joule’s CSO, Dan Robertson, admits that the commercial prospects for their ethanol—as with any biofuel—could be hampered by low oil prices. That is one of the reasons why Phytonix has developed a Synechococcus cyanobacterium that secretes n-butanol. The company also gave it an engineered proton channel that acts as a switch—adding an undisclosed chemical to the brew shifts the microbe from its normal growth phase into butanol production.

In addition to being an alternative to petro-leum, butanol is valuable as a raw material for paints and synthetic rubber, which makes it less vulnerable to oil price fluctuations. “This hasn’t been done before because the science wasn’t there,” says Dannenberg. “Synthetic biology has allowed scientists to leverage photosynthesis and build on it to solve some very significant global challenges.” The process currently oper-ates only at bench scale, but the company plans

Biotech tools are helping industrial manu-facturers convert CO2 into useful products, delegates were told at a conference in late September on Carbon Dioxide as Feedstock for Fuels, Chemistry and Polymers held in Essen, Germany. Bio-based solutions—developed through genetic engineering, high-throughput screening and synthetic biology—are muscling in on what has been traditionally a chemistry-based industry. Bruce Dannenberg, founder and CEO of Phytonix in Black Mountain, North Carolina, a company developing bio-based carbon capture and utilization (CCU) technologies, says that just a few years ago, conferences dedicated to CO2 utilization would have been dominated by electrocatalytic and thermochemical approaches. “There has been a dramatic shift,” he says.

The result is a plethora of demonstration plants around the world showing that microbes can produce fuels and feedstock chemicals from CO2 emissions. “The list is growing—people are realizing that this can be a useful

approach,” says Jennifer Holmgren, CEO of bio-CCU company LanzaTech in Skokie, Illinois.

The chemical industry already re-uses about 200 million metric tons of CO2 per year. Much of it is turned into urea by the Bosch-Meiser process, developed in 1922. That, however, is peanuts by comparison with the biosphere’s capabilities: photosynthesis helps to convert about 100 billion metric tons of the gas into biomass every year (J. Bioprocess. Biotech. 4, 155, 2014).

Industrial processes can also generate use-ful molecules by direct biological conversion of CO2. Take algae. Companies like Sapphire Energy and Cellana, both based in San Diego, use autotrophic algae—which thrive on noth-ing more than light, CO2 and a broth of nutri-ent minerals—to make lipids for conversion into biodiesel, or high-value chemicals such as omega-3 fatty acids (Nat. Biotechnol. 31, 870–873, 2013). Large demonstration facilities are running, and Sapphire expects its first com-

Industrial biotechs turn greenhouse gas into feedstock opportunity

Engineered cyanobacteria act as photobiocatalysts to produce fuel. In the laboratory (top) and soaking up the sun in Joule’s demonstration plant in New Mexico (bottom).

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soluble bicarbonate. In these conditions, carbon extraction is cheaper and uses more benign solvents, compared with today’s energy intensive processes involving potentially toxic amine solvents. The reverse reaction to free CO2 is also faster using this biocatalyst.

Codexis researchers used directed evolu-tion to design a highly specific enzyme for carbon capture. They genetically engineered carbonic anhydrase genes into Escherichia coli, and introduced mutations that altered amino acid sequences around the outside of the enzyme. High-throughput screening identified the toughest mutants, and their beneficial mutations were incorporated into the next round of evolution. After nine rounds, Codexis had screened about 50,000 mutants and produced an enzyme that could withstand the harsh conditions of carbon capture for weeks without its performance suffering (Proc. Natl. Acad. Sci. USA 111, 16436–16441, 2014). The process demanded a degree of automation and data crunching that was only recently possible, says Oscar Alvizo, part of the Codexis team: “I don’t believe this work could have been done 5 years ago.”

CO2 Solutions has been using a simi-lar enzyme at a pilot plant in Salaberry-

all the steel mills in China used this technol-ogy, it would offer emissions cuts equivalent to taking 11 million cars off the road.

Holmgren has encountered initial skepti-cism from some of the heavy-industry com-panies that LanzaTech partners with. “You go to someone at a steel plant and ask them to play with microbes, and they go, ‘Oh really?’,” she says, laughing. But unlike conventional chemical approaches to CCU, which tend to require high-pressure and high-temperature conditions that are only economical at a large scale, bio-CCU plants can be much smaller and less energy-intensive, making them easier to co-locate with factories. “We don’t believe that the future of energy is in large centralized facilities,” says Holmgren.

The dirty carbon in a fossil-fuel plant poses a different set of challenges. Here, too, biotech methods are delivering carbon capture solutions in the form of biocataly-sis—using enzymes as an alternative to tra-ditional chemical reactions (Nat. Biotechnol. 31, 95–96, 2013). CO2 Solutions of Quebec City, Quebec, Canada, partnered with bio-tech company Codexis of Redwood City, California, to develop an enhanced carbonic anhydrase enzyme that transforms CO2 into

Around the world in a month

KENYAEgerton University in collaboration with China’s Nanjing Agricultural University

is building a crop molecular laboratory in Nakuru to help solve problems of low crop productivity. Once the laboratory receives National Biosafety Authority clearance, it plans to begin developing genetically modified crops tailored to Kenyan farming practices.

ARGENTINAArgentina’s government asks

citizens for their opinions on genetically modified crops. The Agriculture, Livestock and Fisheries Ministry is soliciting public comments on Monsanto’s herbicide-resistant soy. Results from this consultation, the first in 20 years, may spur revisions in its report on agricultural biotech.

IRANDanish biotech Novo Nordisk invests $78 million to build a manufacturing plant in Iran expected to come

online in 2020. The company had been in negotiations with Iran’s Food and Drug Administration since before the Islamic Republic reached a nuclear deal with the West in July. The facility will produce Novo Nordisk’s FlexPen insulin devices.

AUSTRALIAThe Australian Court of Appeal rules that farmers of genetically modified

(GM) crops should not be limited in their operations to accommodate nearby organic farmers. The decision comes after an organic farmer filed a case against his neighbor who was planting GM canola, leading to his loss of organic certification.

ROMANIARomania joins a minority of EU countries in allowing the

cultivation of GM crops under a law that permits member states to decide whether or not to grow the crops. Nineteen of the EU’s 28 member states had applied to keep GM crops out of all or part of their territories by the October 4 deadline.

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to build a demonstration plant by the end of next year that will produce up to 1,000 gallons per year.

Rather than inserting a new metabolic pathway into an organism, LanzaTech has optimized Clostridium autoethanogenum, a bacterium that naturally makes acetate (chemically similar to ethanol). The com-pany ramped up the bacteria’s output by using directed evolution, a technique that involves successive rounds of genetic mutation, with the most beneficial alterations taken forward at each stage. The clostridia feed on CO2 and hydrogen, or straight carbon monoxide—a waste gas produced by steel plants and petro-chemical facilities , which is typically burned to produce CO2.

LanzaTech already runs several clostridia demonstration plants on carbon monoxide, including one in partnership with Shougang Steel near Beijing that is producing 100,000 gallons of ethanol per year. The company is now building a plant with the steel-maker ArcelorMittal based in Ghent, Belgium that should produce up to 47,000 tons of ethanol per year after it opens in 2017. The first CO2/hydrogen demonstration plant will be com-pleted next year. Holmgren estimates that if

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Sexed-up beer

One Belgian laboratory’s Friday evening beer fest has ended with a paper describing how to inject flavor into lagers by encouraging some sexual action between yeasts. Kevin Verstrepen, Stijn Mertens and collaborators at VIB laboratory for Systems Biology in Leuven showed with genetic studies that most lager fermentation results from a hybrid species of two parent yeasts—Saccharomyces cerevisiae, and S. eubayanus. Because these two species are so different, crossing them to make more diverse lagers has been unsuccessful. At least, so far. The researchers describe how they optimized growing conditions to foster mating between the two yeasts, which resulted in hundreds of new lager strains (Appl. Environ. Microbiol., doi:10.1128/AEM.02464-15, 25 September 2015). Of the 31 they tested in small-scale beer fermentors, only 10 performed well in terms of fermentation speed and flavor. Two, in particular, fermented even faster and produced novel aroma profiles compared with commercially available lager yeasts.

the technology into more widespread use. For example, mandatory quotas to blend aviation fuel with 5% of fuel from CCU sources would create a valuable market to help fledgling businesses. “That would be a big step, because the aviation industry has no idea how to reduce its CO2 emissions,” says Carus.

Even so, Tuck Seng Wong, a CCU researcher at the University of Sheffield, UK, thinks these approaches are still preferable to pumping waste CO2 into porous rock for-mations deep underground to capture and retain excess carbon. CCU plants can pay for themselves through the chemicals they produce. In contrast, burying CO2 deep underground “is analogous to sweeping the problem under the carpet.”

Mark Peplow Cambridge, UK

de-Valleyfield, Quebec, that captures 10 metric tons of CO2 per day. Crucially, the enzyme allows them to use smaller tem-perature swings to absorb and release CO2. “Compared with other industrial-scale car-bon capture systems, that means we have the lowest capture cost right now,” says Louis Fradette, chief technology officer of CO2 Solutions.

The success of bio-based CCU systems will ultimately depend on economics, says Michael Carus, head of the Nova Institut in Hürth, Germany, an interdisciplinary research center, which organized the Essen conference. “They are not price-competitive yet—but the same is true of biofuels,” he says.

At the conference, delegates discussed what sort of market incentives might pull

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First Rounders Podcast:William RutterBill Rutter is founder, chairman and CEO of Synergenics, which manages a consortium of biotech companies. He was also a founder of Chiron and is credited with bringing the University of California at San Francisco to its prominent position in life sciences research. His discussion with Nature Biotechnology covers building out the labs at UCSF, sequencing the hepatitis C virus and his short stint in the Navy. http://www.nature.com/nbt/podcast/index.html

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