Can we synthetically engineer C4 photosynthesis?

“Photosynthesis as the engine for life on earth has high engineering potential, which has not yet been fully exploited…By step-wise identification of all the components needed for engineering, it will eventually become possible to employ this powerful machinery to increase yields for the future.”

Schuler, ML, Mantegazza, O & Weber, APM, 2016, ‘Engineering C4 photosynthesis into C3 chassis in the synthetic biology age’. The Plant Journal, vol. 87, pp. 62

These lines from the conclusion of the review we write about here are indicative of why so much effort is being put into understanding the more productive C4 photosynthetic system and working to increase important crop yields with it.

Schuler, Mantegazza and Weber’s article in the special issue of The Plant Journal on plant synthetic biology provides an excellent overview of the current status, significant hurdles and possible solutions to those problems of the current research aimed at bolstering rice yield by converting it from the common C3 photosynthesis system to the more efficient C4 system. We’ve previously written about C4 photosynthesis here and here.

C4 photosynthesis

C4 photosynthesis has evolved independently at least 66 times and is likely linked to a sudden drop in atmospheric CO2 levels sometime in the past. It is characterised by the concentration of CO2 around Rubisco (ribulose 1,5-bisphosphate carboxylase/oxygenase), the carbon-assimilating enzyme, reducing the competition that CO2 has with O2 to interact with the enzyme. More CO2 means greater growth and reduced photorespiration, an energy requiring process that is used to remove the O2 reaction products.

The concentration of CO2 in C4 photosynthesis is usually caused by a two-celled (but one-celled is possible) distribution of the process of fixing carbon and the process of reducing it. The two-celled system combines mesophyll (M) cells, which take up the CO2 from the leaf air space, and the bundle sheath (BS) cells, where the Rubisco enzymes reside, the final destination of CO2 for fixation and entry into the Calvin-Benson cycle. These two cells are arranged in concentric layers (called ‘Kranz Anatomy’) around leaf veins, maximising the contact between the two types of cells and increasing the transport of the molecules between them.

M cells convert CO2 to bicarbonate and then into the 4 carbon compound oxaloacetate via an enzyme that doesn’t react with oxygen. The modified compound is then passed to the BS cells where it is reformed into CO2 and fixed by Rubisco to enter the Calvin-Benson cycle.

Basically, by assimilating CO2 away from Rubisco, the plant reduces the ability of Rubisco to interact with O2 and instead it is steadily fed with CO2 from the M cells.

Of course, this description of the process is simplified and although most of the process and main enzymes that carry out the process are known, there are still gaps in our knowledge.

Recent Advances

The gathering of increasing amounts of genomic, trascriptomic and metabolimic data continue to improve our knowledge of C4 photosynthesis, how it evolved and how we might transition C3 crops to use the more efficient carbon fixation method.

Important C4 crop species have had their genomes sequenced and quantitative analysis of transcriptomes have begun to unravel the mystery behind the genes upregulated and downregulated, and the stage of development that these regulatory differences occur, that lead the formation of the Kranz anatomy. What we are finding is that many of the genes involved in C4 photosynthesis exist in C3 plants but are differently regulated at early stages to differentiate the BS and M cells, enable high throughput of metabolites between the cells and to increase the size of vascular tissue to support the increased activity.

Engineering C4 photosynthesis

Our initial attempts to engineer C4 photosynthesis relied on over-expressing one or more enzymes in C3 plants. However, given the enzymes involved in the C4 system are used in the C3 system in multiple alternative pathways, the effects of over-expression were multiple, varied and didn’t have the desire result. The compartmentalisation of reactions, whether in the single or two-celled reactions that make up the distinctive photosystem, is complex.

The notion of being able to engineer C4 photosynthesis is comforted by a number of factors:

1. The main enzymes are already present in C3 photosynthesis;
2. Characteristics such as the passing of metabolites between cells is seen in C3 species such as tobacco plants; and
3. Nature has done it herself in the past on multiple, independent occasions.

But the authors of the paper also note a number of engineering steps that need to be accomplished if we are re-enact evolution ourselves;

1. Higher order veins need to be initiated in plants (it previously being shown that such physical properties were already evolved in plants that subsequently evolved the Kranz anatomy);
2. The ratio of BS to M cells must be increased, ideally in a similar concentric organisation to Kranz anatomy;
3. Enlarging and enriching BS cells with additional chloroplasts;
4. Increasing the connection between M and BS cells;
5. Engineering the different morphologies of the chloroplasts to mimic the morphologies of chloroplasts found in M and BS cells;
6. Mirror the differing roles that M and BS cells take on in C4 photosynthesis so Rubisco reduction of CO2 occurs only in the BS cells with M cells feeding CO2 to the BS cells and excluding the oxidation of O2.

The tools we need

If we are to achieve success we still have some tools to develop and refine.

Chief among this list is a model plant that can be engineered and tested easily with speedy regeneration without requiring too much growing room. The authors point out that rice crops have some limitations in these criteria but identify Brachypodium distachyon as a model C3 plant with a small, annotated genome with quick flowering time, low growing space requirements and an efficient transformation protocol. A model such as this could hasten the engineering, testing and data gathering on conversion which can then be tested on important crop species.

A C4 model plant with similar characteristics is also required. Setaria viridis has previously been suggested as a possible model plant, as has the Fast Flowering Mini Maize.

The ability to drive and control expression of a transgene is also required. Cis-regulatory modules that promote gene expression are still under development in the wider plant synthetic biology area. This leaves a chasm between the tools we have to hand and the possibility that a large number of genes need to be differentially expressed in order to convert C3 photosynthesis to C4 photosynthesis.

Huge strides are being made with genetic manipulation, particularly with the discovery and modification of the CRISPR/Cas 9 system. But, according to the article, the maximum number of genes successfully introduced into a plant, at present, is 9. To induce C4 photosynthesis in a C3 plant, we may need the ability to stably transform a far larger number of genes plus regulatory elements, and do so without disrupting the remainder of the genome or the phenotype characteristics of our food crops.

Even when we do have these tools at the ready, we are still missing some vital information about the genes and regulatory elements that compose C4 photosynthesis. Increasing our knowledge of minutia of genetic composition and regulation of C4 systems compared to C3 systems is still a top priority. Identifying genera with the underlying predisposition that have allowed species within it to evolve from C3 to C4 for comparative analysis, particularly species displaying characteristics of a C3-C4 intermediate with sister taxa displaying C3 and C4 phenotypes, would be idyllic in assisting the study of the evolution. The authors highlight Morandia and Parthenium generas as possible true intermediates between C3 and C4 plants. Programs such as the Grass Phylogeny Working Group and the 1KP (1000 plants) project will greatly assist identifying and genotyping suitable candidates for understanding the genetics behind enhancing crop photosynthesis.

And some suggested means of pushing the research…

It is great to see that not only have the authors elucidated quite extensively the current knowledge and gaps within the field of C4 photosynthesis engineering, but have also suggested a couple of ways of advancing the research.

The first idea they suggested is synthetically replicating a simplified C4 photosynthetic system using known genetic components. The system replicates the targeting of specific enzymes to create a two-celled photosynthesis construct, limiting Rubisco to the BS cells using RNAi to interfere with its transcription in M cells. The article highlights specific transporters that can be used to transport the metabolites between the two cells.

A second suggested idea is using brute force to direct a speedy evolution of a C3 or C3-C4 intermediate species into a C4 plant. Identifying the minimum genetic requirements of a C4 plant in a candidate crop would then be followed by the repetitive growth under the selective pressure of a low CO2 atmosphere. By repeating genomic and transcription analysis of the evolving plant (if successful), a ‘mud-map’ of the road from C3 to C4 plants can be generated and be of enormous use to research seeking to synthetically install the same machinery.

Conclusion

Although its behind a pay-wall, get your hands on this article. Whether it be for a background in C4 photosynthesis or as a springboard for your own research, it is an area of immense potential that should be worthy of an X prize.

ORIGINAL: Legume Laboratory

September 6, 2016

IBM, Local Motors debut Olli, the first Watson-powered self-driving vehicle

Olli hits the road in the Washington, D.C. area and later this year in Miami-Dade County and Las Vegas.

Local Motors CEO and co-founder John B. Rogers, Jr. with "Olli" & IBM, June 15, 2016.Rich Riggins/Feature Photo Service for IBM

IBM, along with the Arizona-based manufacturer Local Motors, debuted the first-ever driverless vehicle to use the Watson cognitive computing platform. Dubbed "Olli," the electric vehicle was unveiled at Local Motors' new facility in National Harbor, Maryland, just outside of Washington, D.C.

Olli, which can carry up to 12 passengers, taps into four Watson APIs (

• Speech to Text, 
• Natural Language Classifier, 
• Entity Extraction and 
• Text to Speech

) to interact with its riders. It can answer questions like "Can I bring my children on board?" and respond to basic operational commands like, "Take me to the closest Mexican restaurant." Olli can also give vehicle diagnostics, answering questions like, "Why are you stopping?"

Olli learns from data produced by more than 30 sensors embedded throughout the vehicle, which will added and adjusted to meet passenger needs and local preferences.

While Olli is the first self-driving vehicle to use IBM Watson Internet of Things (IoT), this isn't Watson's first foray into the automotive industry. IBM launched its IoT for Automotive unit in September of last year, and in March, IBM and Honda announced a deal for Watson technology and analytics to be used in the automaker's Formula One (F1) cars and pits.

IBM demonstrated its commitment to IoT in March of last year, when it announced it was spending $3B over four years to establish a separate IoT business unit, whch later became the Watson IoT business unit.

IBM says that starting Thursday, Olli will be used on public roads locally in Washington, D.C. and will be used in Miami-Dade County and Las Vegas later this year. Miami-Dade County is exploring a pilot program that would deploy several autonomous vehicles to shuttle people around Miami.

ORIGINAL: ZDnet
By Stephanie Condon for Between the Lines
June 16, 2016

A Big Leap for an Artificial Leaf

A new system for making liquid fuel from sunlight, water, and air is a promising step for solar fuels.

The bionic leaf is one step closer to reality.

Daniel Nocera, a professor of energy science at Harvard who pioneered the use of artificial photosynthesis, says that he and his colleague Pamela Silver have devised a system that completes the process of making liquid fuel from sunlight, carbon dioxide, and water. And they’ve done it at an efficiency of 10 percent, using pure carbon dioxide—in other words, one-tenth of the energy in sunlight is captured and turned into fuel. That is much higher than natural photosynthesis, which converts about 1 percent of solar energy into the carbohydrates used by plants, and it could be a milestone in the shift away from fossil fuels. The new system is described in a new paper in Science.

“Bill Gates has said that to solve our energy problems, someday we need to do what photosynthesis does, and that someday we might be able to do it even more efficiently than plants,” says Nocera. “That someday has arrived.”

In nature, plants use sunlight to make carbohydrates from carbon dioxide and water. Artificial photosynthesis seeks to use the same inputs—solar energy, water, and carbon dioxide—to produce energy-dense liquid fuels. Nocera and Silver’s system uses a pair of catalysts to split water into oxygen and hydrogen, and feeds the hydrogen to bacteria along with carbon dioxide. The bacteria, a microörganism that has been bioengineered to specific characteristics, converts the carbon dioxide and hydrogen into liquid fuels.

Several companies, including Joule Unlimited and LanzaTech, are working to produce biofuels from carbon dioxide and hydrogen, but they use bacteria that consume carbon monoxide or carbon dioxide, rather than hydrogen. Nocera’s system, he says, can operate at lower temperatures, higher efficiency, and lower costs.

Nocera’s latest work “is really quite amazing,” says Peidong Yang of the University of California, Berkeley. Yang has developed a similar system with much lower efficiency. “The high performance of this system is unparalleled” in any other artificial photosynthesis system reported to date, he says.

The new system can use pure carbon dioxide in gas form, or carbon dioxide captured from the air—which means it could be carbon-neutral, introducing no additional greenhouse gases into the atmosphere. “The 10 percent number, that’s using pure CO2,” says Nocera. Allowing the bacteria themselves to capture carbon dioxide from the air, he adds, results in an efficiency of 3 to 4 percent—still significantly higher than natural photosynthesis. “That’s the power of biology: these bioörganisms have natural CO2 concentration mechanisms.”

Nocera’s research is distinct from the work being carried out by the Joint Center for Artificial Photosynthesis, a U.S. its fusing of two usually separate fields:

• inorganic chemistry (to split water) and 
• biology (to convert hydrogen and carbon dioxide into fuel). 

“What’s really exciting is the hybrid approach” to artificial photosynthesis, says Co. “It’s exciting to see chemists pairing with biologists to advance the field.”

Commercializing the technology will likely take years. In any case, the prospect of turning sunlight into liquid fuel suddenly looks a lot closer.

ORIGINAL: Technology Review
by Richard Martin
June 7, 2016

China is building the largest waste-to-energy plant in the world

SHL Architects

It will turn a third of Shenzhen's trash into energy every single day.

The Chinese city of Shenzhen plans to tackle its serious waste problem by burning 5,000 tonnes of it a day in what will become the largest waste-to-energy plant in the world. 

The process, which is expected to turn at least a third of the trash into useable electricity, isn’t exactly the best thing for the environment on account of all the CO2 it’ll release, but it'll at least put a nice, big dent in the landfills and illegal dumps that have been building up in Shenzhen. One of these landfills actually killed dozens of people last year when it unexpectedly collapsed.

Expected to be up and running by 2020, the plant is less about generating electricity and more about finding a solution to the existing trash problem - the energy is just a handy bonus. 

According to Adele Peters at Fast Company, the new incinerator is one of 300 waste-to-energy plants that the Chinese government plans on building over the next three years. And while there’s been much debate over just how environmentally friendly (or not, as the case may be) burning all that trash is, many countries around the world have been using the process to essentially 'right the wrongs' of the past.

"Waste-to-energy plants are not an energy solution," Chris Hardie from Schmidt Hammer Lassen Architects, the Denmark-based firm that won a competition to design the plant, told Peters, adding that the amount of greenhouse gases emitted from decomposing landfills is around double the CO2 released by incineration. 

"They are a way of dealing with waste and using this process to generate electricity as a byproduct of the process. Cities have to move towards more recycling and reducing their waste for sure - and of course developing more sources of renewable energy. That is sort of the point we are making by proposing this be the first waste-to-energy plant that has a renewable component to it," he said.

What Hardie is referring to there is the fact that the roof of the massive plant - which will stretch about 1.6 km long (1 mile) - will be topped with around 44,000 square metres of solar panels. 

The idea is that the plant won’t just be about getting rid of trash, it will be providing clean and sustainable electricity to the surrounding city, and inviting members of the public to visit the facility and see it in action.

"The waste challenge is all about education - and experiencing the scale of the challenge is part of that education process," says Hardie. "Think of it like smoking in the 1950s and 1960s - everyone smoked. It was only until a civilisation became educated on how much it was polluting our own bodies did we dramatically stop. Waste is similar. If you don’t realise the damage it is doing, why stop creating waste?"

Ultimately, while burning trash is pretty much a necessary evil at this point, because there’s no point pretending it doesn’t exist, what China should also be focussing on is how to prevent similar build-ups in the future. 

Fast Company points out that by 2020 - the year the plant is expected to be operational - San Francisco plans on being a zero-waste city through some serious composting and recycling efforts. If burning waste is our reality today, let’s hope no waste at all will be our future.

ORIGINAL: Science Alert

BEC CREW

26 FEB 2016

The Ideal Fuel

A nanomaterials chemist has figured out a good way to mimic leaves and turn water and carbon dioxide into things we need.

Peidong Yang

On a sunny day on the campus of the University of California, Berkeley, the peaceful rustling of eucalyptus trees belies the furious chemical activity happening inside every single leaf. Through photosynthesis, leaves use the energy in sunlight to turn water and carbon dioxide into substances that plants need, emitting only oxygen in the process. In a nearby lab, chemist Peidong Yang is building an artificial system that does the same, using arrays of nanowires coupled with engineered bacteria. If something like this is ever scaled up, it would churn out a better version of the fuels we use today—one that does not add to the total amount of carbon dioxide in the air.

Photosynthesis has been very difficult to imitate in the lab. In the 1970s, researchers at the University of Tokyo showed for the first time that a solar-powered device could do what plants do in the first step of photosynthesis: split water into hydrogen and oxygen. After an initial burst of activity, the field stalled. But it has been reborn in several labs thanks to a renewed focus on the energy problem and climate change—and because of the emergence of new technologies.

1. This small reactor filled with chemical precursors and water is heated in an oven to grow titanium dioxide nanowires.

2. Silicon ­nanowires are grown from gaseous ­precursors ­flowing through this ­reactor.

3. Silicon ­nanowires can also be grown on larger ­surfaces such as this wafer. It gets cut into pieces that serve as ­electrodes inside the device. 

4. Bacteria in this incubator will be seeded on an ­electrode to act as living catalysts.

Yang’s lab is improving on a basic design that was developed in the 1970s at the National Renewable Energy Laboratory. It has two light-sensitive electrodes coated with a catalyst—Yang is using nickel, which is inexpensive—that together split water into oxygen and hydrogen. In the original setup, the electrodes were flat, but Yang instead uses arrays of nanowires made from silicon and other semiconductors. Because the nanowires have 100 times the surface area of flat electrodes that could fit into the same space, they can hold more of the catalyst, greatly boosting the efficiency of the reaction.

However, splitting water is the easy half of photosynthesis. Plants go further, using the hydrogen from water in reactions that turn carbon from the air into complex molecules. Yang wants to do this too. After all, our planes and cars don’t run on hydrogen; they need gasoline and other chemically complex fuels.

5. Inside this device, light ­powers a reaction in which water and ­carbon dioxide are ­converted to fuel. Tubing allows the reaction’s side product—pure ­oxygen—to escape. 

6 and 7. Some bacteria in the system produce methane, which can be used directly as a fuel; others make acetate, which is fed to other genetically engineered bacteria to make fuels and plastics. Here, engineered E. colifeed on acetate.

8. Analytical tools including mass spectrometers are used to ­verify that the bacteria made the desired chemical. So far, the system is as efficient as natural photosynthesis.

To catalyze that part of the process, Yang relies on another technology that wasn’t around in the ’70s. He and colleagues have shown that genetically engineered bacteria nestled amid the nanowires function as “living catalysts.” They take up the hydrogen split from the water and combine it with carbon dioxide to make methane and other hydrocarbons that are needed for fuels or plastics. The bugs do this with natural enzymes that carry out a series of reactions chemists have not yet been able to master with synthetic catalysts.

Yang’s system currently matches the efficiency of photosynthesis, storing under 1 percent of the energy captured from sunlight in the form of chemical bonds. That’s not bad for a proof-of-concept demonstration, but making it more efficient and thus cost-effective will be essential.

Yang hopes to eventually switch to synthetic catalysts instead of bacteria, which are tricky to keep alive. But fully eliminating the bugs might not be necessary, given the urgent need for clean fuels. “If it has to be a hybrid approach, that’s okay,” he says.

ORIGINAL: MIT News

By Katherine Bourzac | Photographs by RC Rivera

December 22, 2015

This Tower Purifies a Million Cubit Feet of Air an Hour

Daan Roosegaard worked with scientist Bob Ursem and European Nano Solutions to create the Smog Free Tower. STUDIO ROOSEGAARDE

The tower, shown here in Rotterdam, sucks pollution from the air into its chambers and purifies it. STUDIO ROOSEGAARDE

The air is sucked in from a ventilation system at the top of the tower.STUDIO ROOSEGAARDE

And then it enters a chamber where the pollution becomes positively charged before latching onto grounded electrodes. The particles then becomes trapped in the chambers while the clean air escapes.Studio Roosegaarde

Smog. STUDIO ROOSEGAARDE

Roosegaard is compressing smog particles into jewelry, because why not? STUDIO ROOSEGAARDE

Daan Roosegaard worked with scientist Bob Ursem and European Nano Solutions to create the Smog Free Tower. STUDIO ROOSEGAARDE

THERE’S A MASSIVE vacuum cleaner in the middle of a Rotterdam park and it’s sucking all the smog out of the air. A decent portion of it, anyway. And it isn’t a vacuum, exactly. It looks nothing like a Dyson or a Hoover. It’s probably more accurate to describe it as the world’s largest air purifier.

The Smog Free Tower, as it’s called, is a collaboration between Dutch designer Daan Roosegaard, Delft Technology University researcher Bob Ursem, and European Nano Solutions, a green tech company in the Netherlands. The metal tower, nearly 23 feet tall, can purify up to 1 million cubic feet of air every hour. To put that in perspective, the Smog Free Tower would need just 10 hours to purify enough air to fill Madison Square Garden. “When this baby is up and running for the day you can clean a small neighborhood,” says Roosegaard.

It does this by ionizing airborne smog particles. Particles smaller than 10 micrometers in diameter (about the width of a cotton fiber) are tiny enough to inhale and can be harmful to the heart and lungs. 

Ursem, who has been researching ionization since the early 2000s, says a radial ventilation system at the top of the tower (powered by wind energy) draws in dirty air, which enters a chamber where particles smaller than 15 micrometers are given a positive charge. Like iron shavings drawn to a magnet, the the positively charged particles attach themselves to a grounded counter electrode in the chamber. The clean air is then expelled through vents in the lower part of the tower, surrounding the structure in a bubble of clean air. Ursem notes that this process doesn’t produce ozone, like many other ionic air purifiers, because the particles are charged with positive voltage rather than a negative.

Ursem has used the same technique in hospital purification systems, parking garages, and along roadsides, but the tower is by far the biggest and prettiest application of his technology. Indeed, it’s meant to be a design object as much as a technological innovation. Roosegaard is known for wacky, socially conscious design projects—he’s the same guy who did the glowing Smart Highway in the Netherlands. He says making the tower beautiful brings widespread attention to a problem typically hidden behind bureaucracy. “I’m tired of design being about chairs, tables, lamps, new cars, and new watches,” he says. “It’s boring, we have enough of this stuff. Let’s focus on the real issues in life.”

Roosegaard has been working with Ursem and ENS, the company that fabricated the tower, for two years to bring it into existence, and now that it’s up and running, he says people are intrigued. He just returned from Mumbai where he spoke to city officials about installing a similar tower in a park, and officials in Mexico City, Paris, and Beijing (the smoggy city that inspired the project) also are interested. “We’ve gotten a lot of requests from property developers who want to place it in a few filthy rich neighborhoods of course, and I tend to say no to these right now,” he says. “I think that it should be in a public space.”

Roosegaard has plans to take the tower on a “smog-free tour” in the coming year so he can demonstrate the tower’s abilities in cities around the world. It’s a little bit of showmanship that he hopes will garner even more attention for the machine, which he calls a “shrine-like temple of clean air.” Roosegaard admits that his tower isn’t a final solution for cleaning a city’s air. “The real solution everybody knows,” he says, adding that it’s more systematic than clearing a hole of clean air in the sky. He views the Smog Free tower as an initial step in a bottom-up approach to cleaner air, with citizens acting as the driving force. “How can we create a city where in 10 years these towers aren’t necessary anymore?” he says. “This is the bridge towards the solution.”

ORIGINAL: Wired

09.18.15

Making polymers from a greenhouse gas

A future where power plants feed their carbon dioxide directly into an adjacent production facility instead of spewing it up a chimney and into the atmosphere is definitely possible, because CO2 isn't just an undesirable greenhouse gas; it is also a good source of carbon for processes like polymer production. In the journal Angewandte Chemie, American scientists have now introduced a two-step, one-pot conversion of CO2 and epoxides to polycarbonate block copolymers that contain both water-soluble and hydrophobic regions and can aggregate into nanoparticles or micelles.

CO2 and epoxides (highly reactive compounds with a three-membered ring made of two carbon atoms and one oxygen atom) can be polymerized to form polycarbonates in reactions that use special catalysts. These processes are a more environmentally friendly alternative to conventional production processes and have already been introduced by several companies. However, because current CO2-based polycarbonates are hydrophobic and have no functional groups, their applications are limited. In particular, biomedical applications, an area where the use of biocompatible polycarbonates is well established, have been left out.

A team led by Donald J. Darensbourg along with graduate student Yanyan Wang at Texas A&M University (USA) has provided a solution. For the first time, the researchers have been able to produce amphiphilic polycarbonate block copolymers in which both the hydrophilic and hydrophobic regions are based on CO2. They were also able to incorporate a variety of functional and charged groups into the polymers. Because it is very difficult to find building blocks to make hydrophilic polycarbonates, the researchers used a trick: they polymerized first and attached the water-soluble groups afterwards.

The entire process is even a "one-pot reaction": The researchers first produce the hydrophobic regions by polymerizing CO2 and propylene oxide (as the epoxide component). In the same vessel, they then change to a different building block, allyl glycidyl ether (AGE), an epoxide with a double bond in its side chain, and continue the polymerization. The AGE-containing polymer grows on both ends of the existing polycarbonate, leading to a triblock copolymer. The length of the blocks can be controlled precisely. Subsequently a "thiol–ene click reaction" can be used to simply "click" a water-soluble group into place at the double bond. This makes it possible to attach acidic and/or basic groups that carry a positive or negative charge in certain pH ranges. Some of the amphiphilic polycarbonates made by this method are able to aggregate into particles or micelles in a self-organization process. This, and the ability to attach bioactive substances, for example, could provide many more possibilities for biomedical applications.

Explore further:  

Bristly Spheres as Capsules

More information: "Construction of Versatile and Functional Nanostructures Derived from CO2-based Polycarbonates." Angew. Chem. Int. Ed.. doi: 10.1002/anie.201505076


Related Stories 

Bristly Spheres as Capsules March 6, 2009
(PhysOrg.com) -- Amphiphilic molecules, which have one water-friendly (hydrophilic) end and one water-repellant (hydrophobic) end, spontaneously aggregate in aqueous solutions to make superstructures like capsules or bilayers. ...

Copolymerization of metal nanoparticles for the production of colloidal plasmonic copolymers February 24, 2014

Molecules can copolymerize to form longer composite chains; it turns out that nanoparticles called colloidal particles can also copolymerize to make hybrid nanostructures. The fact that these reactions occur in a very similar ...

 
Polymers that can be fine-tuned for optimal effect could help fight multidrug-resistant infections July 2, 2014

The rise of drug-resistant microbes is a major challenge facing medicine. The World Health Organization's 2014 report on global surveillance of antimicrobial resistance warns of the very real possibility of the twenty-first ...

 
Sulfur fluoride exchange—a powerful new reaction for click chemistry September 1, 2014
(Phys.org) —The coupling of molecular building blocks nearly as easy as "snapping" them together can be realized by means of the "click chemistry" tool kit. American scientists have now introduced another achievement for ...

New silicon peptide biopolymers February 6, 2015
Copolymers made from synthetic and biomimetic components open new and interesting perspectives as biocompatible, biodegradable materials that can also be given biological functionality. In the journal Angewandte Chemie, French ... 

Catalyst that converts carbon dioxide to carbon monoxide in water June 3, 2015
(Phys.org)—Clean energy, or energy that comes from renewable sources, is of interest in the developing world. One path toward clean energy is harnessing solar energy and converting it into electrical energy, which could ...

Recommended for you 

Understanding the firefly's glow August 4, 2015
Now we know how fireflies get their glow going. 

Graphene drives potential for the next-generation of fuel-efficient cars August 4, 2015
Harvesting heat produced by a car's engine which would otherwise be wasted and using it to recharge the car's batteries or powering the air-conditioning system could be a significant feature in the next generation of hybrid ... 

Materials scientists take big step toward tougher ductile ceramics August 4, 2015
A team of materials scientists at the UCLA Henry Samueli School of Engineering and Applied Science is exploring ways to create tough ceramics, a long sought-after class of materials that would be exceptionally hard, capable ... 

Scientists devise method for rescuing genetic material from formaldehyde-treated tissue samples August 4, 2015
Each year, millions of tissue samples are collected from cancer patients and preserved in formaldehyde. The chemical "freezes" the cancer cells within the sample, allowing physicians to look at the disease and plan a specific ... 

Sol-gel capacitor dielectric offers record-high energy storage July 30, 2015
Using a hybrid silica sol-gel material and self-assembled monolayers of a common fatty acid, researchers have developed a new capacitor dielectric material that provides an electrical energy storage capacity rivaling certain ...

 
Origins of life: New model may explain emergence of self-replication on early Earth July 28, 2015
When life on Earth began nearly 4 billion years ago, long before humans, dinosaurs or even the earliest single-celled forms of life roamed, it may have started as a hiccup rather than a roar: small, simple molecular building ...


ORIGINAL: Phys.org
July 28, 2015

Conversion of renewable resources into hydrocarbons through fermentation

History

Global Bioenergies was founded in 2008 jointly by Marc Delcourt, a biotechnologies entrepreneur, and Philippe Marlière, the program’s creator. The company developed in several stages.

Stage 1 – Proof of concept

To begin with, Global Bioenergies successfully set up a laboratory-scale prototype to provide proof of concept for its technology.

The Company also laid the foundations for its intellectual property, and it now holds exclusive rights to a constantly growing patent portfolio.

Stage 2 – Laboratory development

Secondly, after its IPO on the Alternext market, the Company refined its process on a laboratory scale. To this day, it continues to make performance improvements.

Stage 3 – Industrialization

Stage 3, which began when €23 million in funds were raised in mid-2013, was devoted to industrialization. An industrial pilot with an isobutene production capacity of 10 tonnes p.a. was set up at the Pomacle-Bazancourt agro-industrial site close to Reims.

BioMA+ Program: collaboration agreement with Arkema and the CNRS. Started up in October 2013 for three years. €5.2 million in government funding (Investissements d’Avenir program), with Global Bioenergies obtaining €4.0 million. The objective is to establish a new process for converting sugar into isobutene and then methacrylic acid, a key ingredient in acrylic paint.

The process at the pilot plant, which became fully operational in early 2015, has already been refined for an industrial environment, having been scaled up by a factor of ten from the laboratory. Initial batches of isobutene have now been shipped to Arkema in pressurized containers.

An industrial-scale demonstrator with an isobutene production capacity of 100 tonnes p.a. is currently being built at the Leuna refinery in Germany and is scheduled for start-up in 2016.

It has been financed by a €5.7 million subsidy from the German government and a €4.4 million loan from a consortium of French banks. This demonstrator represents the final stage in industrialization of the isobutene process.

Stage four – Commercialization

Add caption

The fourth stage – launching the technology in the marketplace – is only just beginning. The plan to set up the first full-scale plant in France is already starting to come together. Global Bioenergies and Cristal Union, France’s number two sugar manufacturer, formed a 50/50 joint venture in May 2015.

IBN-One has obtained a license from Global Bioenergies to use the isobutene process for production of up to 50,000 tonnes p.a. IBN-One gradually aims to raise the funds it needs for engineering work and construction of the facility. The chemicals and fuel sectors, as well as public-sector authorities, will also play a role in helping IBN-One to establish itself.

In Europe and the United States, the tax incentives for biofuels would enable it to achieve profitability at its first few plants at oil prices above $50 per barrel.

Secondly, several dozen plants each producing 50,000 to 200,000 tonnes of isobutene, butadiene or propylene would then be operated profitably in the plastics and rubbers market. An oil price of at least $85 per barrel would be needed for these ventures. These plants will drive Global Bioenergies’ growth, as it will receive milestone payments and royalties from each of them. The facilities to be located in rural areas will each create around 50 direct jobs, which cannot be relocated abroad.

In the longer term, once peak oil has been reached and oil prices are back above $150 per barrel, the isobutene process may become indispensable.

Isooctane, produced by condensing two isobutene compounds, is the gold standard and can be mixed with fossil-based gasoline, without any blending ratio restrictions or any alteration of properties.

Production of drop-in fuels has raised the prospect that existing infrastructure can be maintained once fossil oil runs out and dispenses with the need to set up additional storage, transportation and distribution infrastructure. A decentralized and greener new world will gradually take shape.

If it comes to fruition, Global Bioenergies’ isobutene process may be used in hundreds, if not thousands of plants that will radically transform the global industrial landscape.

Isobutene process

Global Bioenergies was founded in 2008 with a unique goal – to develop a process converting renewable resources (sugar, crops, agricultural and forestry waste) into isobutene, one of the main petroleum derivatives.

Schéma général du procédé

This new approach based on gas fermentation has two major advantages and will bring down operating costs:

The main drawback of conventional fermentation processes – the liquid product that builds up in the reactor is toxic to the micro-organism – has been overcome since the product evaporates spontaneously. The process can even be implemented almost continuously.

The purification stage is simpler – the isobutene merely has to be extracted from the air, CO2 and steam, rather than having to separate a liquid compound from a complex and varying cultured broth. Conventional methods, tried and tested over many decades, can achieve this.

Why use this process?

Because isobutene, one of the major building blocks of the petrochemicals industry, represents a market worth $25 billion and may one day address an additional market worth $400 billion. 15 million tonnes are produced every year and are turned into plastics, rubbers and fuels.

Arbre - produit de l'isobutène

Why is a scientifical challenge?

Because micro-organisms do not naturally produce isobutene. And it’s easy to understand why. A micro-organism converting its nutrients into isobutene, a volatile compound, would soon lose its carbon stores and be discarded by evolution. We had to “recode the software” in micro-organisms in our laboratory to make them produce the compound.

For the first time, an artificial metabolic pathway – a complex series of enzymatic reactions – was created from scratch. When implanted into a host micro-organism, it can convert sugars into isobutene in a several-stage process.

Bactérie modifiée pour produire de l'isobutène

This ground-breaking achievement has opened up the entirely new domain of synthetic biology.

Modified micro-organisms have been used in fermenters on an ever-increasing scale, initially in a laboratory and now in an industrial pilot. They are intended for use in plants in rural areas where they can produce fuel, plastics and rubbers using this alternative technology.

Fermenteur industriel

Image: Audi/Global Bioenergies The first batch of Audi “e-benzin” has been produced by cooperation partner Global Bioenergies.

Highly pure Audi “e-benzin” developed with Global Bioenergies

Next step calls for total elimination of biomass

Audi logs another success in the development of sustainable, synthetic fuels: Collaboration partner Global Bioenergies has produced the first batch of Audi “e-benzin”.

Audi “e-benzin” is synthetically produced without the use of petroleum. It is 100-percent iso-octane and therefore has an outstanding octane rating of RON 100. Because Audi “e-benzin” contains no sulfur or benzene, it burns very cleanly. It is thus a high-grade fuel that enables engines to use high compression ratios for enhanced efficiency. Audi will test the new fuel in the lab and in test engines. In the medium term, the company and Global Bioenergies aim to modify the process so that it requires no biomass, instead requiring just water, hydrogen, CO2 and sunlight.

Reiner Mangold, Head of Sustainable Product Development at AUDI AG, emphasized that Audi has taken a broad-based approach to the development of CO2-neutral, non-fossil fuels. “Global Bioenergies has demonstrated the viability of the Audi “e-benzin” production process. That is a big step in our Audi e-fuels strategy.” Audi is already producing larger quantities of “e-gas” (synthetic methane) on an industrial scale for its customers. Other research projects with various partners are dedicated to Audi “e-ethanol”, Audi “e-diesel” and Audi “e-benzin”.

Global Bioenergies S.A. operates a pilot plant for the production of isobutene, the starting material for Audi “e-benzin”, in the French town of Pomacle, near Reims. Isobutene is produced there from renewable raw materials rather than the usual petroleum. Another project partner is the Fraunhofer Center for Chemical-Biotechnological Processes (CPB) in Leuna, Saxony-Anhalt. Researchers there use hydrogen to transform the gaseous isobutene into liquid iso-octane. Global Bioenergies is building a demonstration plant at the Fraunhofer Center that will begin producing larger quantities in 2016.

ORIGINAL: Global Bioenergies  Audi Media Services

26 MAY 2015