Department of Chemical and Biomolecular Engineering
Korea Advanced Institute of Science and Technology

Faculty

Yong Keun Chang (장용근)

Professor

Tel : +82-42-350-3927
Fax : +82-42-350-3910
E-mail : ychang@kaist.ac.kr
Homepage : http://bsel.kaist.ac.kr
Education
- 1987 : Purdue Univ. (Ph.D. in Chem. Eng.)
- 1980 : KAIST (M.S. in Chem. Eng.)
- 1978 : Seoul National Univ. (B.S. in Chem. Eng.)

Employment and Professional Experience
- 1988 ~ Present : Professor, KAIST
- 1987 ~ 1988 : Post-Doc. Researcher, U. C. Irvine
- 1980 ~ 1983 : Research Engineer, KIST

Awards and Honors
- Professor Award, SooDang Foundation (2001)
- Research Award, KAIST (2003)
- Contribution Award, The Korean Society for Biotechnology and Bioengineering (KSBB) (2003)
- Contribution Award, KSBB (2005)
- SongAm Award for Academic Excellency, The Korean Society for Microbiology and Biotechnology (2006)
- Award for Excellent Science/Technology Paper, The Korean Federation of Science and Technology Societies (KFSTS) (2006)
- Award for Excellent Science/Technology Paper, KFSTS (2008)
- Contribution Award, KSBB (2010)
- Contribution Award, KSBB (2013)
- Grand Award for Academic Excellency, KSBB (2013)

Research interests
- Process Systems Biology: systems biology-based microbial strains and fermentation processes development for biopharmaceuticals production
- Bioseparation: separation processes development for various bioproducts recovery

Selected Publications
1. Construction of asm2 Deletion Mutant of Actinosynnema pretiosumand Medium Optimization for Ansamitocin P-3 Production Using Statistical Approach, Journal of Microbiology and Biotechnology, 16(9), 1338-1346, (2006)
2. Production of Soluble Human Interleukin-6 in Cytoplasm by Fed-batch Culture ofRecombinant E. coli, Biotechnology Progress, 21(2):524-531 (2005)
3. Removal of Organic Acid Salts from Simulated Fermentation Broth Containing Succinate by Nanofiltration, Journal of Membrane Science, 246(1):49-57 (2005)
4. Recovery of Ammonium Lactate and Removal of Hardness from Fermentation Broth by Nanofiltration, Biotechnology Progress, 20(3):764-70 (2004)
5. Continuous Culture of Immobilized Streptomyces Cells for Kasugamycin Production, Biotechnology Progress, 17, 453-461 (2001)

BioSystem Engineering Laboratory
Systems Biotechnology, Biopharmaceuticals, Biorefinary & Bioenergy, Bioseparation

Process Systems Biology: Strain and Process Development for Biopharmaceuticals Production We are developing new genetically-engineered Streptomyces strains and new fermentation processes for one-step production of valienamine and valiolamine which are precursors of voglibose, a diabetes drug. The gene clusters for their biosynthesis have been coined by minimizingand optimization of validamycin or salbostatin gene cluster. Among a number of environmental factors affecting secondary metabolites production, the broth pH and dissolved oxygen concentration have the most profound effects on productivity and thus process economics. We have found that by imposing an acidic pH shock at the beginning of the culture the productivity can be enhanced remarkably. We are analyzing this phenomenon in transcriptome level by DNA chip analysis and RT (real time)-PCR, and also in proteome level by 2D-gel analysis and MALDI-TOF analysis, for example to identify major biological factors and signal transduction pathways involved. The knowledge being found is to be applied for strain improvement and process optimization. We are also developing Streptomyces strains with enhenced oxygen affinity and/or productivity by introducing hemoprotein genes and analyzing the effects of the hemoprotein genes on secondary metabolites production. Bioseparation: membrane separation and chromatography We are developing processes based on desalting electrodialysis (DSED), water-splitting electrodialysis (WSED), nanofiltration (NF) and/or chromatography for the recovery and purification of organic acids and secondary metabolites produced by fermentation. We have developed and modeled two different two-stage lactic acid recovery processes based on DSED and WSED, and NF and WSED, respectively. We are modelling many unusual and peculiar phenomena observed in NF based on Donnan equilibrium and size exclusion. Recently, we are developing and modelling various separation processes consisting of NF and ion-exchange chromatography for the recovery of potassium clavulanate (an antibiotic agent), valienamine, valiolamine, etc.