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Bioengineers develop a new strategy for accurate prediction of cellular metabolic fluxes
A team of pioneering South Korean scientists has developed a new strategy for accurately predicting cellular metabolic fluxes under various genotypic and environmental conditions. This groundbreaking research is published in the journal Proceedings of the National Academy of Sciences of the USA (PNAS) on August 2, 2010.
To understand cellular metabolism and predict its metabolic capability at systems-level, systems biological analysis by modeling and simulation of metabolic network plays an important role. The team from the Korea Advanced Institute of Science and Technology (KAIST), led by Distinguished Professor Sang Yup Lee, focused their research on the development of a new strategy for more accurate prediction of cellular metabolism.
“For strain improvement, biologists have made every effort to understand the global picture of biological systems and investigate the changes of all metabolic fluxes of the system under changing genotypic and environmental conditions,” said Lee. The accumulation of omics data, including genome, transcriptome, proteome, metabolome, and fluxome, provides an opportunity to understand the cellular physiology and metabolic characteristics at systems-level. With the availability of the fully annotated genome sequence, the genome-scale in silico (means “performed on computer or via computer simulation.”) metabolic models for a number of organisms have been successfully developed to improve our understanding on these biological systems. With these advances, the development of new simulation methods to analyze and integrate systematically large amounts of biological data and predict cellular metabolic capability for systems biological analysis is important.
Information used to reconstruct the genome-scale in silico cell is not yet complete, which can make the simulation results different from the physiological performances of the real cell. Thus, additional information and procedures, such as providing additional constraints (constraint: a term to exclude incorrect metabolic fluxes by restricting the solution space of in silico cell) to the model, are often incorporated to improve the accuracy of the in silico cell.
By employing information generated from the genome sequence and annotation, the KAIST team developed a new set of constraints, called Grouping Reaction (GR) constraints, to accurately predict metabolic fluxes. Based on the genomic information, functionally related reactions were organized into different groups. These groups were considered for the generation of GR constraints, as condition- and objective function- independent constraints. Since the method developed in this study does not require complex information but only the genome sequence and annotation, this strategy can be applied to any organism with a completely annotated genome sequence.
“As we become increasingly concerned with environmental problems and the limits of fossil resources, bio-based production of chemicals from renewable biomass has been receiving great attention. Systems biological analysis by modeling and simulation of biological systems, to understand cellular metabolism and identify the targets for the strain improvement, has provided a new paradigm for developing successful bioprocesses,” concluded Lee. This new strategy for predicting cellular metabolism is expected to contribute to more accurate determination of cellular metabolic characteristics, and consequently to the development of metabolic engineering strategies for the efficient production of important industrial products and identification of new drug targets in pathogens.”
2010.08.05 View 14157 -
Native-like Spider Silk Produced in Metabolically Engineered Bacterium
Microscopic picture of 285 kilodalton recombinant spider silk fiber
Researchers have long envied spiders’ ability to manufacture silk that is light-weighted while as strong and tough as steel or Kevlar. Indeed, finer than human hair, five times stronger by weight than steel, and three times tougher than the top quality man-made fiber Kevlar, spider dragline silk is an ideal material for numerous applications. Suggested industrial applications have ranged from parachute cords and protective clothing to composite materials in aircrafts. Also, many biomedical applications are envisioned due to its biocompatibility and biodegradability.
Unfortunately, natural dragline silk cannot be conveniently obtained by farming spiders because they are highly territorial and aggressive. To develop a more sustainable process, can scientists mass-produce artificial silk while maintaining the amazing properties of native silk? That is something Sang Yup Lee at the Korea Advanced Institute of Science and Technology (KAIST) in Daejeon, the Republic of Korea, and his collaborators, Professor Young Hwan Park at Seoul National University and Professor David Kaplan at Tufts University, wanted to figure out. Their method is very similar to what spiders essentially do: first, expression of recombinant silk proteins; second, making the soluble silk proteins into water-insoluble fibers through spinning.
For the successful expression of high molecular weight spider silk protein, Professor Lee and his colleagues pieced together the silk gene from chemically synthesized oligonucleotides, and then inserted it into the expression host (in this case, an industrially safe bacterium Escherichia coli which is normally found in our gut). Initially, the bacterium refused to the challenging task of producing high molecular weight spider silk protein due to the unique characteristics of the protein, such as extremely large size, repetitive nature of the protein structure, and biased abundance of a particular amino acid glycine. “To make E. coli synthesize this ultra high molecular weight (as big as 285 kilodalton) spider silk protein having highly repetitive amino acid sequence, we helped E. coli overcome the difficulties by systems metabolic engineering,” says Sang Yup Lee, Distinguished Professor of KAIST, who led this project. His team boosted the pool of glycyl-tRNA, the major building block of spider silk protein synthesis. “We could obtain appreciable expression of the 285 kilodalton spider silk protein, which is the largest recombinant silk protein ever produced in E. coli. That was really incredible.” says Dr. Xia.
But this was only step one. The KAIST team performed high-cell-density cultures for mass production of the recombinant spider silk protein. Then, the team developed a simple, easy to scale-up purification process for the recombinant spider silk protein. The purified spider silk protein could be spun into beautiful silk fiber. To study the mechanical properties of the artificial spider silk, the researchers determined tenacity, elongation, and Young’s modulus, the three critical mechanical parameters that represent a fiber’s strength, extensibility, and stiffness. Importantly, the artificial fiber displayed the tenacity, elongation, and Young’s modulus of 508 MPa, 15%, and 21 GPa, respectively, which are comparable to those of the native spider silk.
“We have offered an overall platform for mass production of native-like spider dragline silk. This platform would enable us to have broader industrial and biomedical applications for spider silk. Moreover, many other silk-like biomaterials such as elastin, collagen, byssus, resilin, and other repetitive proteins have similar features to spider silk protein. Thus, our platform should also be useful for their efficient bio-based production and applications,” concludes Professor Lee.
This work is published on July 26 in the Proceedings of the National Academy of Sciences (PNAS) online.
2010.07.28 View 18564 -
The 8th International Conference on Metabolic Engineering was held on June 13-18, 2010 in Jeju Island, South Korea.
From left to right, top row: Distinguished Professor and the conference chair Sang Yup Lee, Sang-Hyup Kim - Secretary to the President of Korea, Dr. Jay Keasling, Dr. Greg Stephanopoulos. Left to right, bottom row: Dr. William Provine, Dr. Terry Papoutsakis, Dr, Jens Nielsen, Dr. Lars Nielsen.
The importance of industrial biotechnology that produces chemicals and materials from renewable biomass is increasing due to climate change and the dearth of natural resources. Industrial biotechnology refers to a technology that allows sustainable bio-based production of chemicals and materials that could enrich human"s lives using microorganisms. This is where metabolic engineering comes into play for successful application of microorganisms, in which they are engineered in our intended way for improved production capability.
The 8th International Conference on Metabolic Engineering, the longest running conference of its kind, was held on June 13-18, 2010 at the International Convention Center in Jeju Island, South Korea. Distinguished Professor Sang Yup Lee of KAIST, Dean of College of Life Science and Bioengineering and Co-Director of Institute for the BioCentury, chaired the conference with the main theme of "metabolic engineering for green growth."
With 300 delegates selected by the committee, papers on production of biofuels, chemicals, biopolymers, and pharmaceutics and the development of fundamental metabolic engineering techniques were presented at the conference along with examples of successful commercialization of products developed by several global companies.
Sang Hyup Kim, Secretary to the President of Korea, gave an opening plenary lecture entitled "Korean green growth initiative," to inform experts from around the globe of the leadership on green growth in Korea. Young Hoon Park, President of Korea Research Institute of Bioscience and Biotechnology (KRIBB, Korea) delivered his congratulatory address.
Sang Hyup Kim said, "Hosting an international conference in Korea on metabolic engineering, which forms a core technology necessary for the development of environmentally friendly processes for producing chemicals and biofuels from renewable biomass, is very meaningful as green growth is a big issue around the globe. This is a great chance to show the excellence of Korea"s green growth associated technology to experts in metabolic engineering and industrial biotechnology."
A total of 47 invited lectures in this conference included recent and important topics, for instance, "Synthetic biology for synthetic fuels" by Dr. Jay Keasling from the Joint BioEnergy Institute (USA), "Microbial oil production from renewable feedstocks" by Dr. Greg Stephanopoulos from MIT (USA), "Yeast as a platform cell factory for production of fuels and chemicals" by Dr. Jens Nielsen from Chalmers University (Sweden), "Mammalian synthetic biology - from tools to therapies" by Dr. Martin Fussengger from ETH (Switzerland), "Building, modeling, and applications of metabolic and transcriptional regulatory networks at a genome-scale" by Dr. Bernhard Palsson from the University of California - San Diego (USA), "Genome analysis and engineering Eschericha coli for sucrose utilization" by Dr. Lars Nielsen from the University of Queensland (Australia), "Artificial microorganisms by synthetic biology" by Dr. Daniel Gibson from JCVI (USA), and "Metabolomics and its applications" by Dr. Masaru Tomita from Keio University (Japan). From Korea, Dr. Jin Hwan Park from the research group of Dr. Sang Yup Lee at KAIST presented "Systems metabolic engineering of Escherichia coli for amino acid production," and Dr. Ji Hyun Kim from KRIBB presented "Genome sequencing and omics systems analysis of the protein cell factory of Escherichia coli".
Global companies involved in biorefinery presented their recent research outcomes with emphasis on commercialized technologies. They included "Metabolic and process engineering for commercial outcomes" by Dr. William Provine from DuPont (USA), "Direct production of 1,4-butanediol from renewable feedstocks" by Dr. Mark Burk from Genomatica (USA), "Development of an economically sustainable bioprocess for the production of bio 1,2-propanediol" by Dr. Francis Voelker from Metabolic Explorer (France), "Biotechnology to the bottom-line: low pH lactic acid production at industrial scale" by Dr. Pirkko Suominen from Cargill (USA), "Bioisoprene™: traditional monomer, traditional chemistry, sustainable source" by Dr. Gregg Whited from Danisco (USA) and "Efficient production of pharmaceuticals by engineered fungi" by Dr. Roel Bovenberg from DSM (Netherlands).
This biennial conference also presented the International Metabolic Engineering Award (expanded version of the previous Merck Metabolic Engineering Award) to the best metabolic engineer in the world. The 2010 International Metabolic Engineering Award went to Dr. E. Terry Papoutsakis from the University of Delaware (USA) who has contributed to the production of biobutanol through the metabolic engineering of Clostridia in the last three decades, and he gave an award lecture. Dr. Sang Yup Lee, the current chair of the upcoming conference, was the previous recipient of this award at the last metabolic engineering conference in 2008.
In addition to the invited lectures, a total of 156 carefully selected poster papers were chosen for presentation, and awards were presented to the best posters after rigorous review by the committee members. Such awards included "The 2010 Metabolic Engineering Best Poster Award" and the "2010 Young Metabolic Engineer Award" from the Metabolic Engineering conference, and prestigious international journal awards, including "Wiley Biotechnology Journal Best Poster Award", "Wiley Biotechnology and Bioengineering Best Poster Award" and "Elsevier Metabolic Engineering Best Paper Award." Dr. Catherine Goodman, a senior editor of Nature Chemical Biology, also presented the "Nature Chemical Biology Best Poster Award on Metabolic Engineering."
Regarding this conference, Dr. Sang Yup Lee, the conference chair, said, "This conference is the best international conference in the field of metabolic engineering, which is held every two years, and Korea is the first Asian country to host it. All the experts and students spend time together from early breakfast to late poster sessions, which is a distinct feature of this conference. Although the number of delegates had typically been limited to 200, around 300 delegates were selected this year to accept more attendees from many people who have been interested in metabolic engineering. Also, it is very fitting that "green growth" is the main topic of this conference because Korea is playing a key role in this field. I"m grateful to the Lotte Scholarship Foundation, COFCO, GS Caltex, Bioneer, US DOE, US NSF, Daesang, CJ Cheiljedang, Genomatica and DuPont who provided us with generous financial support that allowed the successful organization of this conference."
The conference was organized by the Systems Biology Research Project Team supported by the Ministry of Eduction, Science and Technology (MEST), Microbial Frontier Research Project Group, World Class University Project Group at KAIST, Institute for the BioCentury at KAIST, Korean Society for Biotechnology and Bioengineering, and the Engineering Conference International (ECI) of the United States.
Inquiries: Professor Sang Yup Lee (+82-42-350-3930), industrialbio@gmail.com
2010.06.25 View 19698 -
New drug targeting method for microbial pathogens developed using in silico cell
A ripple effect is expected on the new antibacterial discovery using “in silico” cells
Featured as a journal cover paper of Molecular BioSystems
A research team of Distinguished Professor Sang Yup Lee at KAIST recently constructed an in silico cell of a microbial pathogen that is resistant to antibiotics and developed a new drug targeting method that could effectively disrupt the pathogen"s growth using the in silico cell.
Hyun Uk Kim, a graduate research assistant at the Department of Chemical and Biomolecular Engineering, KAIST, conducted this study as a part of his thesis research, and the study was featured as a journal cover paper in the February issue of Molecular BioSystems this year, published by The Royal Society of Chemistry based in Europe.
It was relatively easy to treat infectious microbes using antibiotics in the past. However, the overdose of antibiotics has caused pathogens to increase their resistance to various antibiotics, and it has become more difficult to cure infectious diseases these days.
A representative microbial pathogen is Acinetobacter baumannaii. Originally isolated from soils and water, this microorganism did not have resistance to antibiotics, and hence it was easy to eradicate them if infected. However, within a decade, this miroorganism has transformed into a dreadful super-bacterium resistant to antibiotics and caused many casualties among the U.S. and French soldiers who were injured from the recent Iraqi war and infected with Acinetobacter baumannaii.
Professor Lee’s group constructed an in silico cell of this A. baumannii by computationally collecting, integrating, and analyzing the biological information of the bacterium, scattered over various databases and literatures, in order to study this organism"s genomic features and system-wide metabolic characteristics. Furthermore, they employed this in silico cell for integrative approaches, including several network analysis and analysis of essential reactions and metabolites, to predict drug targets that effectively disrupt the pathogen"s growth. Final drug targets are the ones that selectively kill pathogens without harming human body.
Here, essential reactions refer to enzymatic reactions required for normal metabolic functioning in organisms, while essential metabolites indicate chemical compounds required in the metabolism for proper functioning, and their removal brings about the effect of simultaneously disrupting their associated enzymes that interact with them.
This study attempted to predict highly reliable drug targets by systematically scanning biological components, including metabolic genes, enzymatic reactions, that constitute an in silico cell in a short period of time.
This research achievement is highly regarded as it, for the first time, systematically scanned essential metabolites for the effective drug targets using the concept of systems biology, and paved the way for a new antibacterial discovery. This study is also expected to contribute to elucidating the infectious mechanism caused by pathogens.
"Although tons of genomic information is poured in at this moment, application research that efficiently converts this preliminary information into actually useful information is still lagged behind. In this regard, this study is meaningful in that medically useful information is generated from the genomic information of Acinetobacter baumannii," says Professor Lee. "In particular, development of this organism"s in silico cell allows generation of new knowledge regarding essential genes and enzymatic reactions under specific conditions," he added.
This study was supported by the Korean Systems Biology Project of the Ministry of Education, Science and Technology, and the patent for the development of in silico cells of microbial pathogens and drug targeting methods has been filed.
[Picture 1 Cells in silico]
[Picture 2 A process of generating drug targets without harming human body while effectively disrupting the growth of a pathogen, after predicting metabolites from in silico cells]
2010.04.05 View 16828 -
Photonic crystals allow the fabrication of miniaturized spectrometers
By Courtesy of Nanowerk
Photonic crystals allow the fabrication of miniaturized spectrometers
(Nanowerk Spotlight) Spectrometers are used in materials analysis by measuring the absorption of light by a surface or chemical substance. These instruments measure properties of light over a specific portion of the electromagnetic spectrum. In conventional spectrometers, a diffraction grating splits the light source into several beams with different propagation directions according to the wavelength of the light. Thus, to achieve sufficient spatial separation for intensity measurements at a small slit, a long light path – i.e., a large instrument – is required.
However, for lab-on-a-chip or microTAS (total analysis system) applications, the spectrometer must be integrated into a sub-centimeter scale device to produce a stand-alone platform. To achieve this, researchers at the Korea Advanced Institute of Science and Technology (KAIST) propose a new paradigm in which the spectrometer is based on an array of photonic crystals with different bandgaps.
"Because photonic crystals refelct light of different wavelengths selectively depending on their bandgaps, we can generate reflected light spanning the entire wavelength range for analysis at different spatial positions using patterned photonic crystals," Seung-Man Yang, Director of the National Creative Research Initiative Center for Intergrated Optofluidic Systems and Professor of the Department of Chemical & Biomolecular Engineering at KAIST, tells Nanowerk. "Therefore, when the light source impinges on the patterned photonic crytals, we can construct the spectrum using the reflection intensity profile from the constituent photonic crystals."
Photonic crystals – also known as photonic band gap material – are similar to semiconductors, only that the electrons are replaced by photons (i.e. light). By creating periodic structures out of materials with contrast in their dielectric constants, it becomes possible to guide the flow of light through the photonic crystals in a way similar to how electrons are directed through doped regions of semiconductors. The photonic band gap (that forbids propagation of a certain frequency range of light) gives rise to distinct optical phenomena and enables one to control light with amazing facility and produce effects that are impossible with conventional optics.
To demonstrate this new concept based on patterned photonic crystals, Yang and his group used non-close-packed colloidal crystals of silica particles dispersed in photocurable resin. Due to the repulsive interparticle potential, monodisperse silica particles spontaneously crystallize into non-close-packed face-centered cubic (fcc) structures at volume fractions above 0.1. Therefore, the particle volume fraction determines both the lattice constant and the bandgap position.
a) Optical image of an ETPTA film containing porous photonic crystal stripe patterns with 20 different bandgaps. b) Reflectance spectra from the 20 strips. c) Optical microscope image of the middle region with the parallel stripe pattern (denoted as white-dotted box in a). d) Cross-sectional SEM images of first, sixth, eleventh and seventeenth strips. The scale bars in a, c and d are 1 cm, 2mm and 2 µm, respectively. (reprinted with permission from Wiley-VCH Verlag)
Reporting their findings in a recent issue of Advanced Materials ("Integration of Colloidal Photonic Crystals toward Miniaturized Spectrometers"), the KAIST team has demonstrated the integration of colloidal photonic crystals with 20 different bandgaps into freestanding films (prepared by soft lithography), and their application as a spectrometer.
Yang explains that the team was able to precisely control the photonic bandgap by varying the particle size and volume fration.
"The prepared colloidal composite structures showed high physical rigidity and chemical resistivity" he says. "The composite structure is suitable for spectroscopic use due to the small full widths at half maximum (FWHMs) of the reflectance spectra, which mean that there is little overlap of the reflectance spectra of neighboring photonic crystal strips."
"On the other hand" says Yang, "porous photonic crystals showed large FWHMs and high reflectivities, which should prove useful in many practical photonic applications that require high optical performance and physical rigidity as well as simple and inexpensive preparation."
In addition to fabricating miniaturized spectrometers, which can for instance be integrated into small lab-on-a-chip devices, these integrated photonic crystals can be potentially used for tunable band reflection mirrors, optical switches, and tunable lasing cavities. Moreover, patterned photonic crystals with RGB colors are well-suited for use in reflection-mode microdisplay devices.
Yang points out that, although the spectrometric resolution can be reduced by employing the smaller bandgap interval and photonic bandwidth, there is a limitation. "Now, we are studying photonic crystals with continuous modulation of bandgap position. We expect that the photonic crystals can reduce the resolution to 0.01 nm."
By Michael Berger. Copyright 2010 Nanowerk
2010.03.17 View 14424
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Opening Ceremony Held on February 3, 2010 for Intellectual Property Training Center
KAIST Opened Training Center for Young Entrepreneurs
Commissioner Jung-Sik Koh of Korean Intellectual Property Office (KIPO) and KAIST faculty members including Soon-Hong Jang, Vice President of Operations and Kwang-Hyung Lee, Dean of Academic Affairs Office, joined an opening ceremony held on February 3rd, 2010 to launch a training center for the next generation entrepreneurs who will lead the intellectual property (IP) industry in Korea.
The training center was built in cooperation with KIPO to educate and support young entrepreneurs and prepare them to become tomorrow’s IP business leaders like Bill Gates of Microsoft and Google’s founders, Larry Page and Sergey Brin.
Going through a vigorous selection process, a total of 101 students (51 for intermediate and 50 for advanced level) were chosen last December for an orientation program that will begin February 3rd and continue through February 5th. In addition to the training center at KAIST, KIPO supported to launch another training center at the Pohang University of Science and Technology (POSTECH), which has been up and running since January 27th, 2010.
2010.02.04 View 14135 -
Prof. Lee"s Team Succeeds in Producing Plastics Without Use of Fossil Fuels
A team of scientists led by Prof. Sang-Yup Lee of the Department of Biological Sciences at KAIST have succeeded in producing the polymers used for everyday plastics through bioengineering, rather than through the use of fossil fuel based chemicals, the university authorities said on Tuesday (Nov. 24).
This groundbreaking research, which may now allow for the production of environmentally conscious plastics, has been published in two papers in the journal Biotechnology and Bioengineering.
Polymers are molecules found in everyday life in the form of plastics and rubbers. The team consisted of scientists from KAIST and Korean chemical company LG Chem focused their research on polylactic acid (PLA), a bio-based polymer which holds the key to producing plastics through natural and renewable resources.
"The polyesters and other polymers we use everyday are mostly derived from fossil oils made through the refinery or chemical process," said Lee. "The idea of producing polymers from renewable biomass has attracted much attention due to the increasing concerns of environmental problems and the limited nature of fossil resources. PLA is considered a good alternative to petroleum based plastics as it is both biodegradable and has a low toxicity to humans."
Until now PLA has been produced in a two-step fermentation and chemical process of polymerization, which is both complex and expensive. Now, through the use of a metabolically engineered strain of E.coli, the team has developed a one-stage process which produces polylactic acid and its copolymers through direct fermentation. This makes the renewable production of PLA and lactate-containing copolymers cheaper and more commercially viable.
"By developing a strategy which combines metabolic engineering and enzyme engineering, we"ve developed an efficient bio-based one-step production process for PLA and its copolymers," said Lee. "This means that a developed E. coli strain is now capable of efficiently producing unnatural polymers, through a one-step fermentation process,"
This combined approach of systems-level metabolic engineering and enzyme engineering now allows for the production of polymer and polyester based products through direct microbial fermentation of renewable resources.
"Global warming and other environmental problems are urging us to develop sustainable processes based on renewable resources," concluded Lee. "This new strategy should be generally useful for developing other engineered organisms capable of producing various unnatural polymers by direct fermentation from renewable resources".
2009.11.30 View 15119 -
Prof. Sang-Yup Lee Founding Member of Board of Editors of mBop
Prof. Sang-Yup Lee of the Department of Chemical and Biomolecular Engineering at KAIST has been appointed as one of the founding board of editors of the mBio which will be launched next year, the university reported on Friday (Nov. 20).
mBio is the American Society for Microbiology"s first all-online, open access journal which will be launched in next May. According to the mBio website, the journal"s scope "will reflect the enormity of the microbial world, a highly interconnected biosphere where microbes interact with living and non-living matter to produce outcomes that range from symbiosis to pathogenesis, energy acquisition and conversion, climate change, geologic change, food and drug production, and even animal behavioral change."
Prof. Lee, LG Chem Chair Professor, is currently the Dean of the College of Life Science and Bioengineering and director of the Center for Systems and Synthetic Biotechnology. He received his B.S. in Chemical Engineering from Seoul National Univeristy in Korea and his M.S. and Ph.D. in Chemical Engineering from Northwestern University.
As of September 2009, he has published 298 journal papers and has more than 440 patents either registered or applied. Also, he has published 47 books/book chapters, "Systems Biology and Biotechnology of Escherichia Coli" being the latest.
His research interests are systems biology and biotechnology, industrial biotechnology, metabolic engineering, synthetic biology and nanobiotechnology. In particular, he has pioneered systems metabolic engineering, which integrates systems biology with metabolic engineering, for the development of micropoganisms possessing superior properties for industrial applications.
2009.11.20 View 12706 -
Prof. Woo's Team Discovers Eco-Friendly Solid-Oxide Fuel Cell System
A KAIST research team led by Prof. Seong-Ihl Woo of the Department of Chemical & Biomolecular Engineering has found a method to use glycerol, a byproduct from the production of biodiesel, as fuel for solid oxide fuel cells (SOFC), university authorities said on Tuesday (Oct. 27).
The research finding shows that glycerol can be an environmentally sustainable fuel when it is used for operating SOFCs with internal reforming, instead of hydrogen and methane. The finding was published in the Oct. 14, 2009 online edition of ChemSusChem, a sister journal of Angewandte Chemie, the world"s leading chemistry journal.
Biodiesel is an attractive alternative energy source because of its low sulfur content and demand is growing worldwide as oil price soars. Bio-derived glycerol will not contribute to the greenhouse effect and has the potential to contribute to reducing global warming.
Currently, glycereol is used as a raw material in the cosmetic, pharmacy, food, and tobacco industries. However, its supply exceeds its demand as the volume of biodiesel production increases. The production of 1 ton of biodiesel produces 0.1 ton of glycerol. Many researchers have investigated various routes for the consumption of surplus glycerol.
The research is expected to contribute to sustainable growth by reducing the emissions of carbon dioxide and reusing generated carbon dioxide for the production of biomass. The new method enables manufacturers to use glycerol as a fuel for operating SOFC.
2009.10.28 View 13633 -
Prof. Cho Elected Editor-in-Chief of Systems Biology
Prof. Kwang-Hyun Cho of Department of Bio and Brain Engineering at KAIST has been recently elected editor-in-chief of the Systems Biology, an international journal published by the London-based Institution of Engineering and Technology (IET), the university authorities said on Wednesday (Sept. 23)
By the year 2012, Cho will oversee the editorial process of the journal covering intra- and inter-cellular dynamics, using systems- and signal-oriented approaches. IET, one of the world"s leading professional societies for the engineering and technology community, has a worldwide membership of more than 150,000.
Prof. Cho"s research interests cover the areas of systems science with bio-medical applications including systems biology and bio-inspired engineering based on molecular systems biology. He is currently an editorial board member of Systems and Synthetic Biology (Springer, Netherlands, from 2006), BMC Systems Biology (BMC, London, U.K., from 2007), Gene Regulation and Systems Biology (Libertas Academica, New Zealand, from 2007), and Bulletin of Mathematical Biology (Springer, New York, from 2008), and an editorial advisory board member of Molecular BioSystems (The Royal Society of Chemistry, U.K.).
2009.09.24 View 16402 -
Prof. Lee"s Team Pioneers Biotechnological Production of Chemical Using Renewable Materials
A research team led by Prof. Sang-Yup Lee of the Bio and Brain Engineering Department at KAIST has succeeded in engineering the bacterium E. coli to produce the industrial chemical putrescine, university authorities said on Monday (Aug. 31).
Putrescine, a four carbon chain diamine, is an important platform chemical with a wide range of applications for the pharmaceutical, agrochemical and chemical industries. It is currently used to synthesize nylon-4,6, a widely used engineering plastic.
The research result, published in the Biotechnology and Bioengineering journal, proviDrdes a renewable alternative to the traditional process using fossil fuels.
Currently the production of putrescine on an industrial scale relies on chemical synthesis, which requires non-renewable petrochemicals and expensive catalyst systems. This process is highly toxic and flammable with potentially severe repercussions for both the environment and human health.
"For the first time we have developed a metabolically engineered E. coli strain that efficiently produces putrescine," said Professor Lee. "The development of a bio-refinery for chemicals and materials is very important in a world where dependency on fossil fuels is an increasing concern."
The team developed a strain of E.coli capable of producing putrescine through metabolic engineering. This is where a cell"s metabolic and regulatory networks are enhanced in order to increase production of a needed material.
First the team weakened or deleted competing metabolic pathways within the E. coli strain before deleting pathways which cause putrescine degradation. They also amplified the crucial enzyme Spec C, which converts the chemical ornithine into putrescine. Finally the putrescine exporter, which allows excretion of intracellularly made putrescine, was engineered while a global regulator was engineered to further increase the concentration of putrescine. The final result of this process was an engineered E.coli strain which produced 24.2 g of putrescine per litre.
However, as it was believed that putrescine is toxic to microorganisms the team had to study putrescine tolerance in E.coli before it could be engineered to overproduce the chemical to the levels needed for industrial production.
The results revealed that E. coli can tolerate at least 0.5 M of putrescine, which is tenfold higher than the usual concentration in the cell. This level of tolerance was an important surprise as it means that E. coli can be engineered to overproduce putrescine to industrially competitive levels.
"The previously expected toxicity of putrescine may explain why its microbial production has been overlooked," said Lee. "Now a metabolically engineered E. coli strain has been developed which is capable of efficiently producing putrescine using renewable methods to an industrial level. This metabolic engineering framework should be useful for developing metabolically engineered microorganisms for the efficient production of other chemicals from renewable resources," he added.
2009.09.01 View 14535 -
KAIST College of Life Sciences and Bioengineering Signs MOU with Harvard
KAIST’s College of Life Sciences and Bioengineering recently signed a memorandum of understanding (MOU) with Harvard University’s Center for Brain Science on July 20, which will allow for joint research and exchange in researchers between the two institutions.
Headed by Director Kenneth Blum, Harvard’s Center for Brain Science leads the world in brain-related research. The new MOU will allow for research cooperation, exchanges of professors, researchers, and students, joint usage of infrastructure and research materials, and finally, sharing of research assignments.
The Dean of the College of Life Sciences and Bioengineering Sang Yup Lee, who concerted efforts to form the MOU said, “This agreement will bring together two of the world’s leading brain-related research teams, and I hope that combining their expertise will bring great advances in brain science and engineering.
KAIST’s College of Life Science and Bioengineering, which is known for its creative interdisciplinary research, is producing exemplary research results in the field of brain science from its Biological Sciences and Bio and Brain Engineering departments.
In addition to cooperation with Harvard, KAIST has also formed partnerships with Emory University, Japan’s RIKEN Brain Institute, and Germany’s Max Planck Institute. Not only does it have a worldwide network pertaining to brain research, but KAIST has also engaged in cooperative research with prominent domestic institutions such as, Asan Medical Center, the Korea Research Institute of Bioscience and Biotechnology, the Korea Research Institute of Standards and Science, and the SK Corporation. Through these connections, KAIST has managed to lead in mutually cooperative brain interdisciplinary research.
2009.08.10 View 16621