S.T. Yang Chemical Engineering Department

Professor Ph.D., Purdue University, 1984 Phone: (614) 292-6611 email: yangst@kcgl1.eng.ohio-state.edu

Description of Research
Potential Thesis Topics
Research Equipment
List of Publications
OSU Chemical Engineering Department Homepage

Description of Research

We are studying several innovative fermentations using immobilized cell bioreactors to produce biochemicals from process wastes and agricultural commodities. The ongoing research projects include anaerobic fermentation of food processing wastes for fuel and chemical production; aerobic fermentation of glucose and lactose to microbial polysaccharides such as xanthan gum; novel simultaneous fermentation-separation processes such as extractive fermentations for organic acids and steroid drug production; and the development of defined mixed cultures for anaerobic and/or aerobic degradation of organic wastes and hazardous environmental pollutants. The projects include development of kinetic and mathematical models for the fermentations. In some cases, we use genetically engineered micro organisms to attain unusual processing capabilities. Using a knowledge-based expert system, we are also developing flow sheet synthesis and process designs for various bioprocesses.

Innovative large-scale bioreactor systems for production of biologically active compounds using recombinant microbial cells, plant cells, or animal cells are important to the emerging biotechnology industry. We are studying a novel two-stage three-phase fluidized bed bioreactor for continuous production of a recombinant protein and secondary metabolic products. Cur group is also developing a novel fibrous bed bioreactor for use in multiphase fermentation processes and for cultivating shear-sensitive animal cell cultures. We are also studying a novel gradient particle bed bioreactor for its applications in mixed culture fermentations and biodegradation of toxic chemicals.

The development of novel bioseparation techniques for recovering and purifying proteins and other biological compounds will have a major impact on reducing production costs of biotechnology products. However, most bioseparation techniques are still limited to smallscale, batch operation due to the lack of understanding of fundamental engineering principles for scale-up design. Therefore, we are exploring the feasibility of developing a two-dimensional liquid chromatograph for continuous recovery and monitoring of fermentation products. We are also investigating liquid-liquid extraction using aliphatic amines for recovering and concentrating organic acids from dilute fermentation broth and aqueous two-phase extraction for protein separation. We are studying the effects of downstream processing on protein conformation and activity loss due to protein denaturation and aggregation, focusing on shear and protein-membrane interaction effects from cross-flow membrane filtration. Kinetics and novel processes for protein refolding are also being studied for several enzymes. Ultrafiltration of polysaccharides as a novel method to recover xanthan gum from viscous fermentation broth is also being studied.

[Return to Top]

Potential Thesis Topics

• Novel fibrous bed bioreactors for fermentations and cell cultures.
• A novel gradient particle bed bioreactor for mixed culture fermentation and biodegradation of toxic chemicals.
• A novel two-stage continuous fermentation process for xanthan gum production.
• Extractive fermentation for organic acid production.
• Kinetic study and mathematical modeling of protein refolding.
• Kinetic studies of protein conformation and activity changes during cross-flow membrane filtration.
• Biofiltration of volatile organic compounds (VOC).
• Ultrafiltration of polysaccharide in fermentation broth.

Professional Experience and Organizations

Specialized Research Equipment

[Return to Top]