Dr WEN-TSO LIU is an Associate Professor at the University of Illinois and holds a position as Visiting Associate Professor in ESE at the National University of Singapore (NUS). Prior to NUS, Dr Liu was an assistant professor at the Graduate Institute of Environmental Engineering, National Central University, Taiwan from 1998 to 2001. Dr Liu received his Ph.D. from University of Tokyo, Japan in 1995, and has engaged in post-doctoral researches both at Northwestern University (1997-1998) and NSF-Center for Microbial Ecology at Michigan State University (1995-1997).

Dr. Liu's main research interests and efforts focus on the microbial ecology and molecular microbiology aspects of water and wastewater treatment processes.  This is based on the facts that the microorganisms are the key catalyst for wastewater treatment, and the primary causative agents for the failure of water purification systems and the occurrences of infectious diseases.  To better design, improve and optimize treatment processes in the long run, I collaborate closely with process-based researchers to study water and wastewater treatment processes with emphases on microbial diversity, community structure, function and interaction

Microbial diversity in treatment systems still remains as an interesting puzzle.  Though we now have better understanding than almost two decades ago when the concept of “three domains” (Bacteria, Archaea and Eucarya) based on 16S ribosomal RNA sequences was first proposed, only < 10-15% of the microorganisms present in the biological treatment systems have been described (<1% in other natural environments).  It is reasonable to assume that those microbial populations in treatment process will need to closely interact with each other through special and sometimes yet-to-be-discovered physical, chemical and biological means, forming a structured microbial community.  This microbial community serves a basic element to achieve desired and possibly collective microbial functions or process performance.  Two good examples I have encountered in my research are the anaerobic granulated sludge degrading terephthalate and the biofilms formed or “biofouling” in water purification membrane systems.

Dr. Liu has extensively studied the microbial ecology of enhanced biological phosphorus removal processes (EBPR) and discovered several new insights.  In addition to polyphosphate-accumulating organisms (PAOs) that are able to generate ATP for carbon uptake and storage [e.g., polyhydroxyalkanoate (PHA)] through the hydrolysis of internally stored polyphosphate granules, He has successfully identified another group of organisms, named as glycogen accumulating organisms (GAOs), that can utilize the internally stored glycogen instead of polyphosphate for taking up substrate and subsequently transforming them into the carbon reserve material (e.g., PHA).  He has speculated an internal energy-based competition between PAOs and GAOs.  Several different members of PAOs and GAOs have been successfully identified through cultivation and non-culture based methods.  Some of the bacterial isolates are further characterized and named as Micropruina glycogenica, Tetrasphaera elongates, and Kineosphaera limosa.  For those yet-to-cultured organisms, he has successfully identified the GB group from the gammaproteobacterial lineage and the Defluvicoccus-related species.   One of the figures published was further selected and used as the cover of a very popular text book, Brock Biology of Microorganisms 10th Edition by Madigan, Martinko and Parker, for students majored in Microbiology. Dr. Liu has also extensively studied the microbial ecology of anaerobic methanogenic reactors degrading terephthalate (TA) under mesophilic and thermophilic conditions (20,33).  TA-containing wastewater is produced during the manufacturing of raw plastic materials in large quantities (60-200 million m3 or 6-20 million population equivalent) and high strength (5-20 kg COD m-3) annually.  Degradation of TA under methanogenic conditions is performed by the collaborative interaction between hydrogen-producing TA-fermenting syntrophs and methanogens.  However, due to the lack of understanding in selecting good seed sludge and establishing the syntrophic community, a long time period (lag phase) more than 200-300 days is often required during the reactor start-up.  These drawbacks can significantly increase the operational cost and limit the application of this process at a full-scale level.  To fully understand the microbial functions of those predominant microbial populations in the thermophilic TA-degrading reactor, a community sequencing project or metagenomic project is undertaken with researchers from Mexico, France, Department of Energy labs, Joint Genome Institute.  These collective efforts can provide possible findings to shorten the lag phase during the start-up of a full-scale TA-degrading anaerobic reactor, and can be an alternative solution for anaerobic processes to treat different recalcitrant chemicals and for generating biogases, energy sources.

To support Dr. Liu's research activities, the use of molecular tools is essential.  He has extensive experiences with the use of in-situ whole cell hybridization, 16S rRNA clone library construction and microbial fingerprinting methods to study microbial diversity and structure in environments.  In some cases, these tools can be combined with other methods (e.g., microbial inclusion staining methods and microautoradiography) to link the microbial phylogeny with their functions.  He has developed a rapid molecular community-profiling method, terminal restriction fragment length polymorphism (T-RFLP) of PCR-amplified DNAs, and involved in the development and application of DNA microarray techniques for environmental microbiology studies.   In specific, we have used a "melting curve" approach to monitor the both the hybridization and dissociation processes between individual targets and probes.  For this, we have developed an imaging analysis system: LabARRAY.  He will further leverage the ongoing metagenomics project with TA-degrading consortium described above, and combine this approach with microarray techniques to study the microbial function at community level.  Apart from the process-related research, Dr. Liu's recent activities are to bridge biotechnology with nanotechnology for rapid detection of biological contaminants in environments.   “Lab-on-a-chip” device with submicron features has been microfabricated using MEMS-related techniques to perform multiple processes (e.g., microbial sample preparation, reaction and detection) required for detecting targeted microorganisms at single-cell level, and can be made portable for military and on-site use.  Quantum dots are further used as a sensitive fluorescence reporter, and can be integrated into the microfluidic device for the detection of microbial cells and nucleic acid variations.  “Lab-on-a-bead” devices are developed to perform biochemical reactions on a bead surface and shorten the analytical time required to minutes.  To further develop a strong research program in lab-on-a-chip devices for rapid microbial monitoring in environments, he has worked with a good team of researchers at NUS.  At the same time, I have accepted the invitation as a joint appointed faculty member at Institute of Microelectronics, Singapore since 1995.  These efforts should lead to the development of cutting edge microbial and nucleic acid detection systems.

(SEM images of microfluidic devices fabricated in our group in collaboration with
Institute of Microelectronics)

• Associate Professor, University of Illinois (2008-present).

• Visiting Associate Professor, ESE, NUS (2008-present).

• Jointly appointed faculty member, Institute of Microelectronics (2005-2008).

• Guest Professor, Shanghai Jiao-Tong University (2006-2009).

• Assistant Professor/Associate Professor, National University of Singapore (2001-pesent).

• Postdoctoral Scientist, Northwestern University (1997-1998).

• Research Associate, NSF-Center for Microbial Ecology, Michigan State University (1995-97).

• 2005 Young Asian Biotechnologist Prize by The Society for Biotechnology, Japan.

• Institute of Engineering Singapore (IES) publication award 2002 (student category): A merit award was given to a final year student at Department of Civil Engineering for conducting FYP thesis on the development of software, LabArray, for real-time detection and quantification, and post-statistical analysis of chip hybridization signal

• Best Master Thesis supervised, National Science Council of Taiwan, 2001

• Research Award 2000 of National Science Council of Taiwan

• Member, IAWQ (International Association on Water Quality), American Society for Microbiology, Chinese Society of Microbiology, and Chinese Society of Environmental Engineering.

• Secretary: International Water Association, Taiwan branch (2000)

• Committee member for IWA special group on Activated Sludge Population Dynamics (2001-2005)

• Secretary for IWA special group on Activated Sludge Population Dynamics (2005-)

• Associate Editor: Microbes and Environments (2002-2006)

• Editorial Board: Applied and Environmental Microbiology (2004-); Advances in Asian Environmental Engineering (2002-); Microbial Ecology (2006-); The ISME Journal (2006-).

• Reviewer: Journals: Water Research, Water Science & Technology, Water and Environment Research, Applied Biochemistry and Biotechnology, Microbiology-UK, Microbes and Environments, World Journal of Microbiology and Biotechnology, Advances in Asian Environmental Engineering, Chinese Journal of Environmental Engineering, FEBS letter, Applied Environmental Microbiology, Soil Microbiology & Biochemistry, Biotechnology & Bioengineering. Granting agencies etc.: Hong Kong Research Grant Committee, Chinese Society of Environmental Engineering, Taiwan National Science Council, Defense Science & Technology Agency (Singapore).

• Microbial Ecology: Microbial Diversity and Community Functions

• Bio-Nanotechnology: DNA Microchip and Lab-on-a-Chip for microbial detection

• Microbial Biofouling in Membrane Processes

• Water and Wastewater Microbiology:

  • Enhanced biological phosphorus removal

  • Anaerobic biological treatment systems

  • Detection of biological contamnants.

 (Refereed Journal Publications - Updated 30 May 2007)

• Environmental Microbiology

• Wastewater Biotechnology

• Topics in Environmental Biotechnology

• Ph.D., University of Tokyo, Japan, 1995

• M.Eng., University of California at Berkeley, USA, 1992

• M.Sc., Rugters - the State University of New Jersey, USA, 1989

• B.Eng., National Taipei Technological University, Taiwan, 1984