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Recombinant E. Coli As a Biofactory for the Biosynthesis of Diverse Nanomaterials
(Distinguished Professor Lee and PhD candidate Choi) A metabolic research group at KAIST and Chung-Ang University in Korea has developed a recombinant E. coli strain that biosynthesizes 60 different nanomaterials covering 35 elements on the periodic table. Among the elements, the team could biosynthesize 33 novel nanomaterials for the first time, advancing the forward design of nanomaterials through the biosynthesis of various single and multi-elements. The study analyzed the nanomaterial biosynthesis conditions using a Pourbaix diagram to predict the producibility and crystallinity. Researchers studied a Pourbaix diagram to predict the stable chemical species of each element for nanomaterial biosynthesis at varying levels of reduction potential (Eh) and pH. Based on the Pourbaix diagram analyses, the initial pH of the reaction was changed from 6.5 to 7.5, resulting in the biosynthesis of various crystalline nanomaterials that were previously amorphous or not synthesized. This strategy was extended to biosynthesize multi-element nanomaterials. Various single and multi-element nanomaterials biosynthesized in this research can potentially serve as new and novel nanomaterials for industrial applications such as catalysts, chemical sensors, biosensors, bioimaging, drug delivery, and cancer therapy. A research group consisting of PhD candidate Yoojin Choi, Associate Professor Doh Chang Lee, and Distinguished Professor Sang Yup Lee of the Department of Chemical and Biomolecular Engineering at KAIST and Associate Professor Tae Jung Park of the Department of Chemistry at Chung-Ang University reported the synthesis. This study, entitled “Recombinant Escherichia coli as a biofactory for various single- and multi-element nanomaterials,” was published online in the Proceedings of the National Academy of Sciences of the United States of America (PNAS) on May 21. A recent successful biosynthesis of nanomaterials under mild conditions without requiring physical and chemical treatments has triggered the exploration of the full biosynthesis capacity of a biological system for producing a diverse range of nanomaterials as well as for understanding biosynthesis mechanisms for crystalline versus amorphous nanomaterials. There has been increased interest in synthesizing various nanomaterials that have not yet been synthesized for various applications including semiconducting materials, enhanced solar cells, biomedical materials, and many others. This research reports the construction of a recombinant E. coli strain that co-expresses metallothionein, a metal binding protein, and phytochelatin synthase that synthesizes the metal-binding peptide phytochelatin for the biosynthesis of various nanomaterials. Subsequently, an E. coli strain was engineered to produce a diverse range of nanomaterials, including those never biosynthesized before, by using 35 individual elements from the periodic table and also by combining multi-elements. Distinguished Professor Lee said, “An environmentally-friendly and sustainable process is of much interest for producing nanomaterials by not only chemical and physical methods but biological synthesis. Moreover, there has been much attention paid to producing diverse and novel nanomaterials for new industrial applications. This is the first report to predict the biosynthesis of various nanomaterials, by far the largest number of various single- and multi-elements nanomaterials. The strategies used for nanomaterial biosynthesis in this research will be useful for further diversifying the portfolio of nanomaterials that can be manufactured.” Figure: The biosynthesis of diverse nanomaterials using recombinant E. coli. This schematic diagram shows the overall conceptualization of the biosynthesis of various single and multi-element nanomaterials using recombinant E. coli under incubation with corresponding elemental precursors. The 35 elements that were tested to biosynthesize nanomaterials are shown in black circles on the periodic table.
KAIST Researchers Receive Awards at the 13th Asian Congress on Biotechnology
(From left: Seon Young Park, Dr. So Young Choi, and Yoojin Choi) Researchers in the laboratory of KAIST Distinguished Professor Sang Yup Lee from the Department of Chemical and Biomolecular Engineering swept awards at the 13th Asian Congress on Biotechnology held in Thailand last month. The conference awarded a total of eight prizes in the areas of best research and best poster presentation. This is an exceptional case in which members of one research team received almost half of the awards at an international conference. Dr. So Young Choi received the Best Research Award, while Ph.D. candidates Yoojin Choi and Seon Young Park each received the Best Poster Presentation Award at the conference held in Khon Kaen, Thailand from July 23 to 27. The Asian Congress on Biotechnology is an international conference in which scientists and industry experts in Asia and from around the world gather to present recent research findings in the field of biotechnology. At the conference, around 400 researchers in biotechnology from 25 countries, including Korea, gathered to present and discuss various research findings under the theme of “Bioinnovation and Bioeconomy.” Distinguished Professor Sang Yup Lee attended the conference to give the opening plenary lecture on the topic of ‘Systems Strategies in Biotechnology.’ Professor Lee announced, “I have attended international conferences with students for the last 20 years, but this is the first in which my team received three awards at an international conference that only honors a total of eight awards, three for Best Research and five for Best Presentation.” Dr. Choi presented research results on poly (lactate-co-glycolate) (PLGA) synthesis through a biological method using micro-organisms and received the Best Research Award. PLGA is a random copolymer of DL-lactic and glycolic acids and is a biopolymer widely used for biomedical applications. PLGA is biodegradable, biocompatible, and nontoxic, and thus has been approved by the US Food and Drug Administration (FDA) for its use in implants, drug delivery, and sutures. Dr. Choi’s research was deemed to be innovative for synthesizing PLGA from glucose and xylose in cells through metabolic engineering of E.Coli. Dr. Choi received her Ph.D. under the supervision of Distinguished Professor Lee this February and is currently conducting post-doc research. Ph.D. candidate Choi presented her research on the use of recombinant E.Coli for the biological synthesis of various nanoparticles and received the Best Poster Presentation award. Choi used recombinant E.Coli-expressing proteins and peptides that adsorb to heavy metals to biologically synthesize diverse metal nanoparticles such as single-nanoparticle including gold and silver, quantum dots, and magnetic nanoparticles for the first time. The synthesized nanoparticles can be used in the fields of bio-imaging, diagnosis, environment, and energy. Ph.D. candidate Park, who also received the Best Poster Presentation award, synthesized and increased production of astanxanthin, a strong antioxidant found in nature, in E.Coli using metabolic engineering. Astanxanthin is a carotenoid pigment found in salmon and shrimp that widely used in health products and cosmetics.
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