Iowa State University Professor Dr. Zengyi Shao leads research focused on engineering microbial species to convert low-cost feedstocks into value-added chemicals and bioproducts. In collaboration with Professor Dennis Vigil, a compact Continuous Taylor Vortex Fermentor-Extractor-Separator is being developed, which combines fermentation, product extraction, and centrifugal separation within a single system. Pulse 2.0 interviewed Iowa State University Professor Dr. Zengyi Shao to learn more.
Dr. Zengyi Shao’s Background
When asked about her background and research experience, Dr. Zengyi Shao shared:
My name is Dr. Zengyi Shao, and I am currently a professor in the Department of Chemical and Biological Engineering at Iowa State University. My research group focuses on engineering diverse microbial species to convert low-cost feedstocks into value-added chemicals and bioproducts. In this project, I have collaborated closely with my colleague, Professor Dennis Vigil, who has decades of expertise in developing Taylor Vortex reactor technology.
Developing The Taylor Vortex System
When discussing what inspired the Continuous Taylor Vortex Fermentor-Extractor-Separator and the challenges it was designed to address, Dr. Zengyi Shao explained:
The idea for the Continuous Taylor Vortex Fermentor-Extractor-Separator was motivated by a fundamental challenge in biomanufacturing. Most fermentation processes are carried out in stirred-tank reactors, where microbial behavior is strongly influenced by the microenvironment surrounding the cells. At large production scales, gradients in nutrients, oxygen, and other factors create spatial heterogeneity within the reactor. This heterogeneity can significantly affect microbial physiology, causing cells to shift between growth and production states and altering metabolic fluxes. Over time, these imbalances can also contribute to genetic drift, as faster-growing variants are naturally enriched over high-producing cells that are often associated with high metabolic burdens.
We believed that the unique flow patterns generated in the Taylor Vortex reactor could significantly reduce spatial heterogeneity within the culture. By creating a more uniform microenvironment for cells, the system has the potential to improve production stability and increase titer and yield, particularly for small-scale biomanufacturing.
Integrating Three Processes
When asked how the device integrates fermentation, extraction, and separation within one compact system, Dr. Zengyi Shao detailed:
The Continuous Taylor Vortex Fermentor-Extractor-Separator consists of a vertical rotating inner cylinder and a stationary outer concentric cylinder, with the fermentation broth occupying the annular space between them. When the inner cylinder rotates at sufficiently high speeds, toroidal flow structures known as Taylor vortices form within the annulus. These vortices generate strong axial and radial mixing, creating a highly uniform environment with relatively consistent turbulence dissipation throughout the reactor. This flow structure enables very efficient interphase mass transfer for multiphase systems, including gas-liquid and liquid-liquid interactions. As a result, fermentation can achieve comparable product titers and yields while operating at much lower aeration rates than conventional bioreactors.
What makes this system unique is that it integrates fermentation, extraction, and separation within a single compact device. The reactor can operate continuously, and target products can be extracted and separated directly from the fermentation broth using centrifugal forces. By designing the inner cylinder as a hollow structure, emulsions can be passed through it to achieve centrifugal phase separation. This integrated design reduces process complexity while maintaining a more homogeneous environment than commonly used reactors such as stirred tanks, bubble columns, or airlift reactors.
Reducing Costs And Complexity
When discussing how the all-in-one approach could lower costs and operational complexity, Dr. Zengyi Shao outlined:
In our project, we selected fatty alcohols as the target product, and the cost reduction comes from two main aspects. First, fatty alcohols are highly hydrophobic and can be toxic to microbial cells because they disrupt cellular and subcellular membranes. In conventional bioreactors, an organic solvent layer is often added to continuously extract the product and reduce toxicity. However, this typically requires additional downstream processing steps for product separation and solvent recovery. With our design, the strong mixing and built-in centrifugal separation capability allow fermentation, extraction, and phase separation to occur within the same system. This integration streamlines the process and reduces the need for multiple separate unit operations.
Second, the enhanced mass transfer provided by the Taylor vortex flow significantly improves oxygen transfer and liquid-liquid interactions. As a result, the process can operate with substantially lower aeration rates and reduced amounts of extractant compared with conventional bioreactors. Together, these advantages help lower operating costs while simplifying the overall biomanufacturing process.
Potential Beneficiaries
When asked which groups could benefit most from the technology, Dr. Zengyi Shao observed:
This technology has the potential to benefit a broad range of users across the biomanufacturing ecosystem. Academic laboratories would likely benefit first, as the system provides a flexible platform for early-stage prototyping and process development. It allows researchers to study microbial production systems under more controlled and homogeneous conditions while also exploring integrated fermentation and separation strategies.
Startups could then leverage the technology to develop and scale up bioprocesses more efficiently, since the compact, integrated design may reduce capital costs and simplify process development. Ultimately, established manufacturers may benefit as the technology matures and becomes more robust, particularly for applications where process intensification and continuous production can improve efficiency.
That said, additional research and development are still needed to fully optimize the system and demonstrate its performance across different products and production scales.
Expanding Access To Biomanufacturing
When discussing how the system’s modular and portable design could broaden access to advanced biomanufacturing, Dr. Zengyi Shao described:
We envision operating this system in a continuous or semi-continuous manner, which means it does not need to be built at the same large scale as conventional stirred-tank bioreactors to achieve meaningful productivity. Such a modular and portable design can significantly expand access to advanced biomanufacturing capabilities in locations with limited infrastructure or resources. The flexibility could help lower the barrier to entry for developing and testing new bioprocesses while enabling more distributed and adaptable manufacturing models.
Microbial Hosts And Applications
When asked which microbial hosts and products have been tested and what future applications are envisioned, Dr. Zengyi Shao noted:
So far, most of our work has focused on the yeast Yarrowia lipolytica engineered for the production of fatty alcohols, which are widely used as surfactants in industrial and consumer products. This system provides a good model because fatty alcohols are relatively hydrophobic and can create product toxicity challenges, making them well suited for testing the integrated extraction capability of our platform.
We have also conducted preliminary experiments with Issatchenkia orientalis engineered to produce citramalate, primarily to evaluate the scalability of the reactor system, successfully testing scale-up from 1-liter to 14-liter operation.
Looking ahead, we envision applying this platform to the production of other value-added biochemicals, particularly compounds that are relatively hydrophobic and benefit from in situ extraction. The system may also be especially advantageous for highly aerobic microbial hosts, where improved oxygen transfer and enhanced mass transport can significantly improve production efficiency.
Commercialization Potential
When asked how the technology could affect the commercialization timeline for fuel and surfactant precursors, Dr. Zengyi Shao clarified:
At this stage, we are still in the early phases of testing the platform with different types of products. Fatty alcohols are our first target because they are important surfactants. The main limitation at this point is strain performance. To make the process economically viable, we will need to engineer microbial strains capable of producing fatty alcohols at titers roughly an order of magnitude higher than what we currently achieve.
Once high-producing strains are developed, the integrated design of our reactor, combining fermentation, extraction, and separation, could help shorten the commercialization pathway by simplifying process development and reducing downstream processing requirements. This could ultimately accelerate the commercialization of certain bioproducts, such as surfactant, biofuels, and biopolymer precursors, from the laboratory to industrial production.
BioMADE’s Support And Next Steps
When discussing the role of BioMADE and Schmidt Sciences in advancing the project and the next steps toward industry adoption, Dr. Zengyi Shao concluded:
We are very grateful to BioMADE and Schmidt Sciences for supporting this project. To our knowledge, there have not yet been industrial implementations of Taylor vortex devices for bioprocessing. Professor Dennis Vigil previously used Taylor vortex reactors at the bench scale for microalgae cultivation, and this funding has allowed us to expand the concept to a broader range of microbial hosts and bioproducts.
We have begun developing scale-up criteria based on parameters such as mass transfer coefficients and turbulence dissipation rates. However, these scaling rules still need to be validated across a wider range of reactor sizes and with a broader set of microorganisms.
The next steps toward broader industry adoption will involve further optimizing reactor performance and demonstrating reliable operation at larger scales. In particular, we need to better understand how to effectively integrate fermentation with in situ product extraction, which is a key feature of this technology and an important factor for practical implementation.
