Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Synthetic Biology Technique Boosts Microbial Production of Diesel Fuel

27.03.2012
Joint BioEnergy Institute Researchers Develop Dynamic System for Regulating Metabolic Pathways

Significant boosts in the microbial production of clean, green and renewable biodiesel fuel has been achieved with the development of a new technique in synthetic biology by researchers with the U.S. Department of Energy (DOE)’s Joint BioEnergy Institute (JBEI).

This new technique – dubbed a dynamic sensor-regulator system (DSRS) – can detect metabolic changes in microbes during the production of fatty acid-based fuels or chemicals and control the expression of genes affecting that production. The result in one demonstration was a threefold increase in the microbial production of biodiesel from glucose.

“The DSRS is an amazing and powerful new tool, the first example of a synthetic system that can dynamically regulate a metabolic pathway for improving production of fatty acid-based fuels and chemicals while the microbes are in the bioreactor,” says Jay Keasling, CEO of JBEI and one of the world’s foremost practitioners of synthetic biology, who led this research.

Keasling, who also serves as the Associate Laboratory Director for Biosciences at Lawrence Berkeley National Laboratory (Berkeley Lab) is the corresponding author of a paper describing this research in Nature Biotechnology. The paper is titled “Design of a dynamic sensor-regulator system for production of FAbased chemicals and fuels.” Co-authors are Fuzhong Zhang and James Carothers of JBEI’s Fuels Synthesis Division, which is directed by Keasling.

The need for new transportation fuels that are renewable and can be produced in a sustainable fashion has never been more urgent. Scientific studies have consistently shown that liquid fuels derived from plant biomass are one of the best alternatives if a cost-effective means of commercial production can be found. Major research efforts to this end are focused on fatty acids – the energy-rich molecules in plant cells that have been dubbed nature’s petroleum. Fatty acids now serve as the raw materials not only for biodiesel fuel, but also for a wide range of important chemical products including surfactants, solvents and lubricants.

Jay Keasling and Fuzhong Zhang at the Joint BioEnergy Institute (JBEI) obtained a threefold increase in the microbial production of biodiesel from glucose using a dynamic sensor-regulator system they and JBEI’s James Carothers developed. (Photo by Roy Kaltschmidt, Berkeley Lab)

“Microbial production of fuels and chemicals from fatty acids is a greener and sustainable alternative to chemical synthesis,” says Zhang, who is the lead author of the Nature Biology paper. “However, high productivities, titers and yields are essential for microbial production of these chemical products to be economically viable, particularly in the cases of biofuels and low-value bulk chemicals.”

Hampering microbial production of fatty acid-based chemicals has been metabolic imbalances during product synthesis.

“Expression of pathway genes at too low a level creates bottlenecks in biosynthetic pathways, whereas expression at too high a level diverts cellular resources to the production of unnecessary enzymes or intermediate metabolites that might otherwise be devoted to the desired chemical,” Zhang says. “Furthermore, the accumulation of these enzymes and intermediate metabolites can have a toxic effect on the microbes, reducing yield and productivity.”

Using the tools of synthetic biology, there have been several strategies developed to meet this challenge but these previous strategies only provide static control of gene expression levels.

“When a gene expression control system is tuned for a particular condition in the bioreactor and the conditions change, the control system will not be able to respond and product synthesis will suffer as a result,” Zhang says.

The DSRS responds to the metabolic status of the microbe in the bioreactor during synthesis by sensing key intermediate metabolites in an engineered pathway. The DSRS then regulates the genes that control the production and consumption of these intermediates to allow their delivery at levels and rates that optimize the pathway for maximum productivity as conditions change in the bioreactor.

“Nature has evolved sensors that can be used to sense the biosynthetic intermediate, but naturally-occurring regulators will rarely suffice to regulate an engineered pathway because these regulators were evolved to support host survival, rather than making chemicals in large quantity,” Zhang says.

To create their DSRS, Zhang, Keasling and Carothers focused on a strain of Escherichia coli (E. coli) bacteria engineered at JBEI to produce diesel fuel directly from glucose. E. coli is a well-studied microorganism whose natural ability to synthesize fatty acids and exceptional amenability to genetic manipulation make it an ideal target for biofuels research. In this latest work, the JBEI researchers first developed biosensors for a key intermediate metabolite – fatty acyl-CoA – in the diesel biosynthetic pathway. They then developed a set of promoters (segments of DNA) that boost the expression of specific genes in response to cellular acyl-CoA levels. These synthetic promoters only become fully activated when both fatty acids and the inducer reagent known as “IPTG” are present.

“For a tightly regulated metabolic pathway to maximize product yields, it is essential that leaky gene expressions from promoters be eliminated,” Zhang says. “Since our hybrid promoters are repressed until induced by IPTG, and the induction levels can be tuned automatically by the FA/acyl-CoA level, they can be readily used to regulate production of biodiesel and other fatty acid-based chemicals.”

Introducing the DSRS into the biodiesel-producing strain of E.coli improved the stability of this strain and tripled the yield of fuel, reaching 28-percent of the theoretical maximum. With further refinements of the technique, yields should go even higher. The DSRS should also be applicable to the microbial production of other chemical products, both fatty acid-based and beyond.

“Given the large number of natural sensors available, our DSRS strategy can be extended to many other biosynthetic pathways to balance metabolism, increase product titers and yields, and stabilize production hosts,” Zhang says. “It should one day be possible to dynamically regulate any metabolic pathway, regardless of whether a natural sensor is available or not, to make microbial production of commodity chemicals and fuels competitive on a commercial scale.”

This research was supported in part by the DOE Office of Science, and in part by the National Science Foundation through the Synthetic Biology Engineering Research Center (SynBERC).

JBEI is one of three Bioenergy Research Centers established by the DOE’s Office of Science in 2007. It is a scientific partnership led by Berkeley Lab and includes the Sandia National Laboratories, the University of California campuses of Berkeley and Davis, the Carnegie Institution for Science, and the Lawrence Livermore National Laboratory. DOE’s Bioenergy Research Centers support multidisciplinary, multi-institutional research teams pursuing the fundamental scientific breakthroughs needed to make production of cellulosic biofuels, or biofuels from nonfood plant fiber, cost-effective on a national scale.

Lawrence Berkeley National Laboratory addresses the world’s most urgent scientific challenges by advancing sustainable energy, protecting human health, creating new materials, and revealing the origin and fate of the universe. Founded in 1931, Berkeley Lab’s scientific expertise has been recognized with 13 Nobel prizes. The University of California manages Berkeley Lab for the U.S. Department of Energy’s Office of Science. For more, visit www.lbl.gov.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the Unites States, and is working to address some of the most pressing challenges of our time. For more information, please visit the Office of Science website at science.energy.gov.

Additional Information

For more about the Joint BioEnergy Institute (JBEI), visit the Website at www.jbei.org

For more about SynBERC, visit the Website at http://www.synberc.org/

Lynn Yarris | EurekAlert!
Further information:
http://www.lbl.gov

More articles from Power and Electrical Engineering:

nachricht Six-legged robots faster than nature-inspired gait
17.02.2017 | Ecole Polytechnique Fédérale de Lausanne

nachricht Did you know that IR heat plays a central role in the production of chocolates?
14.02.2017 | Heraeus Noblelight GmbH

All articles from Power and Electrical Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>