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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 12614 -
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 17028 -
Professor Thompson
Professor Mary Kathryn Thompson of Civil and Environmental Engineering Department wrote her regular column on correlation between art and engineering, “Engineers, Artists Not on Opposite Ends.” The column was published by the Korea Herald on July 23, 2010. For reading, please click the link below.
http://www.koreaherald.com/opinion/Detail.jsp?newsMLId=20100722000548
2010.07.23 View 9678 -
The thermal fluctuation and elasticity of cell membranes, lipid vesicles, interacting with pore-forming peptides were reported by a research team at KAIST.
A research team from KAIST, consisted of Sung-Min Choi, Professor of Nuclear and Quantum Engineering Department, and Ji-Hwan Lee, a doctoral student in the Department, published a paper on the “thermal fluctuation and elasticity of lipid vesicles interacting with pore-forming peptides.” The paper was carried by Physical Review Letters, an internationally renowned peer-review journal on physics on July 16, 2010.
Cell membranes, which consist of lipid bilayers, play important roles in cells as barriers to maintain concentrations and matrices to host membrane proteins. During cellular processes such as cell fission and fusion, the cell membranes undergo various morphological changes governed by the interplay between protein and lipid membranes. There have been many theoretical and experimental approaches to understand cellular processes driven by protein-lipid membrane interactions. However, it is not fully established how the membrane elastic properties, which play an important role in membrane deformation, are affected by the protein-membrane interactions.
Antimicrobial peptides are one of the most common examples of proteins that modify membrane morphology. While the pore-forming mechanisms of antimicrobial peptides in lipid bilayers have been widely investigated, there have been only a few attempts to understand the mechanisms in terms of membrane elastic properties. In particular, the effects of pore formation on the membrane fluctuation and elastic properties, which provide key information to understand the mechanism of antimicrobial peptide activity, have not been reported yet. The research team reports the thermal fluctuation and elasticity of lipid vesicles interacting with pore-forming peptides, which were measured by neutron spin-echo spectroscopy.
The results of this study are expected to pay an important role in understanding the elastic behavior and morphological changes of cell membranes induced by protein-membrane interactions, and may provide new insights for developing new theoretical models for membrane fluctuations which include the membrane mediated interaction between protein patches.
(a) (b)
Figure
(a) Schematics for bound melittin and pores in lipid bilayers
(b) P NMR signal ratio (with/without Mn2+) of DOPC LUV-melittin vs P/L at 30˚C. The dashed line is a guide for eyes.
2010.07.23 View 11412 -
A new facility at KAIST opened on July 6, 2010.
Ryu Geun-Chul Sports Complelx will allow students, faculty and staff to pause a moment and exhale in the hustle and bustle of their daily lives.
An opening ceremony celebrating the completion of a new facility for the KAIST family was held on July 6, 2010 at the campus. Had it not been for contributions of many people and organizations throughout the nation, among others, Dr. Geun-Chul Ryu, POSCO, Woori Bank, members of KAIST community, parents, and other citizens, it would be impossible to build the facility, said the university.
The Complex, a three-story building with a basement, has an indoor court for basketball and volleyball with 3,000 individual seats, 200 meters of running track, indoor golf range, a fitness center, and other convenient facilities.
Any members of KAIST community can visit the building and relax their body and mind stressed with work and study. It also provides a large space for ceremonial and cultural gatherings such as 2010 KAIST commencement ceremony.
The official name of the building is “Ryu Geun-Chul Sports Complelx,” which was created in appreciation of Dr. Geun-Chul Ryu’s generous act who had donated 57.8 billion won worth of real estate to KAIST in August 2008.
2010.07.07 View 12153 -
President of Israel visited KAIST on June 9, 2010.
President of Israel, Shimon Peres, visited KAIST today on June 9, 2010 to witness the development of science and technology in Korea and explore ways of establishing collaboration and cooperation with industries and universities between Korea and Israel. President Peres led a delegation consisted of the Israeli Mister of Industry, Trade, and Labor, the Minister of Communication, and 60 business leaders from the top companies in the security, infrastructure, communication, high-tech, and water industries.
Upon their arrival to the campus, the Israeli delegation was greeted by KAIST’s humanoid robot, “HUBO,” and then moved to its branch campus, IT Convergence Campus, for a ride of Online Electric Vehicle (OLEV) that has been developed by KAIST. The OLEV receives the necessary power through the cable lines buried underground, so it can be provided with a constant and continuous supply of electricity while running or stopping.
Between roads and OLEVs is nothing but space. There is no electrical wires intricately crossed underbody of the electric car or above the road. The pick-up equipment installed beneath the body of the electric car collects magnetic fields created around the underground cables, which then converts the filed into electricity. The OLEV’s wireless, non-contact charging system made it possible for a battery currently used for hybrid or pure electric cars on the market to be smaller and cheaper.
President Peres expressed a great interest in the technology applied to the OLVE, quoting, “the OLEV system is indeed very impressive.” He talked about efforts being made in Israel with respect to the development of electric cars. The country plans to replace the conventional transportation system with electric cars by constructing a network of battery exchange stations and roadside charge points which allow the cars to be charged whenever they are parked.
“Despite the different approach taken by the two nations for the development of electric cars, I believe that transforming the automobile industry from combustion engine to electric system is the right direction we should all follow. Without addressing the current transportation system that heavily dependent on natural resources, we will not be able to promote “green growth on a global scale,” added President Peres.
In addition to electric cars, President Peres took up a considerable portion of his time to exchange ideas on how to expand cooperative relations between universities in Korea and Israel, specifically in the area of space, biotechnology, nanotechnology, high-tech, renewable and alternative energy, and the EEWS initiatives that have been implemented by KAIST to find answers to global issues such as climate change and depletion of natural resources. The EEWS stands for energy, environment, water, and sustainability.
In response, the president of KAIST pledged to set up a stronger and greater tie with research universities in Israel, particularly called for more collaboration between KAIST and Technion-Israel Institute of Technology.
Also, the Israeli delegation had a tour for several Korean research and development centers in Daedeok Innopolis, located in the City of Daejeon, which is the 2nd largest science and research complex in Korea.
Shimon Peres, the 9th president of Israel, held many of important government positions in Israel, among other things, Prime Minster and Minister of Defense. He won Nobel Peace Prize in 1994, together with Yitzhak Rabin and Yasser Arafat for the conclusion of a peace agreement, Oslo Accords, between Israel and Palestine Liberation Organization.
2010.06.09 View 15396 -
"The 2010 Artificial Intelligence Robot War Competition" begins to receive applications
[Event Notice]
“The 2010 Artificial Intelligence Robot War Competition” begins to receive applications
A good opportunity to gauge the intelligence of your robots
“The 2010 Artificial Intelligence (AI) Robot War Competition” will be held in October 2010, and the Competition has been receiving applications from contestants since April 1st. The deadline for the application will be May 31st, 2010.
Qualified contestants must be a minimum of two, but less than six, team members, and they will compete in one of the two fields: System on Chip (SoC) Taekwon Robot and Humanoid Robot (HURO). Winners will be decided based on the intelligence capabilities presented by a robot’s platform that mimics key functions of the human brain.
SoC Taekwon Robot will compete against one another by using a camera installed on its head to recognize visual images, locations, distances, and gestures of the other competing robot.
HURO competition is a new entry begun this year, and winners will be determined in accordance with the robot’s ability to perform given missions and fights. Missions are to go through a track installed with obstacles, recognize colors and shapes of barriers, and knock down barriers to earn scores. Fighting will be performed in the form of a Korean martial art, Tae-kwon-do.
The Korean government has nominated Robotics as one of the key growth engines to develop IT industry and Korean economy. Robotics converge many of different engineering fields, such as machinery, materials, components, and embedded software. In particular, the SoC is an essential technology for Korea to continuously take lead in the semi-conductor industry in the world, which is an important element for robotics.
SoC stands for System on Chip, an integrated chip that assembles various chips and components to be fabricated together on a single chip, instead of building them on a circuit board. The SoC technology has advantages of higher performance, smaller space requirements, lower memory requirements, higher system reliability, and lower consumer costs.
An artificial intelligence SoC robot is autonomous because it can adapt itself to changes in various environments and reach a given goal without constantly receiving external orders.
For details of the event, please refer to the website of www.socrobotwar.org.
2010.04.06 View 12186
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Interesting research results were published on the use of Twitter.
The number of “followers” on your Twitter account does not necessarily mean that “Your opinions matter much” to other people.
A KAIST graduate researcher, Mi-Young Cha, joined an interesting project that studies the influence of a popular social media, Twitter. Most of Twitter users today consider the number of followers as a measurement of their influence on the social sphere. According to the research paper, however, this connection does not seem to standing together. For details, please click the link below for an article published by the New York Times.
Dr. Cha received all of her post secondary education degrees in Computer Science, including her Ph.D. in 2008, from KAIST. Since 2008 till now, she has been a post doctoral researcher at Max Planck Institute for Software Systems (MPI-SWS) based in Germany.
[New York Times Article, March 19, 2010]
http://www.nytimes.com/external/readwriteweb/2010/03/19/19readwriteweb-the-million-follower-fallacy-audience-size-d-3203.html
2010.04.05 View 12451
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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 14932
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Prime Minister Lars Løkke Rasmussen of the Kingdom of Denmark visited KAIST on March 11, 2010.
Prime Minister Lars Løkke Rasmussen of the Kingdom of Denmark visited KAIST on March 11, 2010. HUBO, a humanoid robotdeveloped by KAIST, gave a warm welcome to the prime minister and his delegation.
Prime Minister Lars Løkke Rasmussen of Denmark visited Moon-Ji Campus of KAIST on March 11, 2010 and had a chance to meet a humanoid robot, HUBO. Since the first appearance in 2005, HUBO has been continuously developed by KAIST for further refinements.
HUBO welcomed the prime minister and offered him a flower bouquet. They also shook hands and exchanged small talks in Danish, which made the delegation pleasantly surprised.
The Danish delegation had a ride on Online Electric Vehicle (OLEV) and showed a great interest in the technology applied therein.
The prime minister said, “Denmark has a keen interest in green technology, and I was very impressed by OLEV. It is just amazing to see how fast KAIST has developed as an outstanding research university in the world during a short period of time.”
President Lee Myung-bak invited the Danish prime minister to discuss current international developments, including issues involving the Korean Peninsula, and ways to enhance bilateral cooperation in such areas as trade, investment, renewable energy and green growth.
2010.03.17 View 12303
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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 13281
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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 14036