A Practical Guide to Stirred Tank Bioreactor Selection
Updated: Aug 28
The stirred tank bioreactor (STR) remains one of the most widely used platforms in biotechnology because of its flexibility, scalability, and proven performance across a broad range of processes. From early-stage laboratory research to pilot production and commercial manufacturing, stirred tank systems can be configured to support very different biological processes.
This article classifies stirred tank bioreactors along three practical dimensions: application (what you are cultivating), construction (how the vessel is made), and scale (how much you need to produce).
Understanding these three dimensions provides a useful framework for selecting a bioreactor that fits both your current process and your longer-term bioprocess development strategy.
Main Types of Stirred Tank Bioreactors by Application
The most fundamental distinction in stirred tank bioreactor classification is based on the organism being cultivated. The same stirred tank platform may support both microbial and cell culture processes, but the engineering requirements differ significantly.
Microbial Bioreactors
Microbial bioreactors, or fermenters, are primarily designed for bacteria, yeast, and fungi. These microorganisms generally grow rapidly, reach high cell densities, and tolerate higher shear and mixing intensity. As a result, microbial fermentation focuses on efficient oxygen transfer, vigorous mixing, and effective heat removal.
Key features:
High shear tolerance — Microorganisms can generally withstand stronger agitation and turbulence than mammalian cells.
Efficient gas–liquid transfer — High aeration rates and power input help meet the high oxygen demand of rapidly growing microbial cultures.
Intensive agitation — Multiple impellers, such as Rushton turbines, provide vigorous mixing and effective gas dispersion.
High-density cultivation — Designed to support rapid growth and high biomass concentrations.
Cell Culture Bioreactors
Cell culture bioreactors are designed for mammalian, insect, and other sensitive eukaryotic cells. Because these cells are more vulnerable to mechanical stress and environmental fluctuations, the process emphasizes gentle fluid handling, stable culture conditions, and precise control of critical parameters.
Key features:
Low-shear mixing — Effective but gentle agitation maintains a homogeneous culture environment throughout the vessel while minimizing mechanical stress on sensitive cells.
Controlled aeration — Oxygen is supplied at a controlled rate to meet cellular demand without creating excessive turbulence or bubble-related stress.
Tight environmental control — Temperature, pH, dissolved oxygen, and CO₂ are closely monitored to maintain suitable conditions for cell growth.
CO₂-based pH regulation — CO₂ can be used as part of the buffering system in many mammalian cell culture processes, with acid or base addition used as needed.
Special Application Bioreactors
Certain bioprocesses require specialized bioreactor designs to accommodate unique cultivation conditions. LAB1ST provides customized bioreactors and fermenters engineered with specialized geometries, agitation systems, or process controls to meet specific cultivation requirements.
Customized Photobioreactor
Single-Use vs. Multi-Use Bioreactors
Stirred tank bioreactors can also be classified by how the product-contact system is used between batches.
Single-Use Bioreactors
Single-use bioreactors (SUBs), also known as disposable bioreactors, use pre-sterilized product-contact assemblies—typically flexible polymer bags with integrated tubing, filters, and connectors. SUBs are widely used in mammalian cell culture and clinical manufacturing where rapid changeover, process flexibility, and reduced facility requirements are important.
Key features:
High process flexibility — Bags can be supplied with preassembled tubing, sterile connectors, sampling ports, filters, and disposable sensors to simplify system setup.
Reduced contamination risk — Closed, disposable fluid paths minimize product exposure and reduce the risk of cross-contamination between batches.
Reduced cleaning burden — Since product-contact components are discarded after use, routine cleaning procedures and associated validation requirements are greatly reduced.
Lower facility and capital requirements — Single-use systems generally require less fixed infrastructure, utility capacity, and cleaning equipment than conventional bioreactor facilities.
Multi-Use Bioreactors
Multi-use bioreactors are designed for repeated use with cleaning and sterilization between batches. They are commonly available as glass bioreactors for laboratory applications and stainless steel bioreactors for pilot and production environments.
Glass Bioreactor
Working volumes typically up to 10 L
Full transparency—allowing real-time visual observation of the culture
Lower cost than stainless steel at small scale
Autoclavable for repeated sterilization
Chemical inertness of borosilicate glass, suitable for sensitive applications
Stainless Steel Bioreactor
Superior mechanical strength and pressure resistance
Excellent durability for long-term, high-volume production
Full customization options for sensors, spargers, tubes, or integrated frames
Lower operating cost per batch, despite higher upfront capital
Quick Comparison
Feature | Single-Use Bioreactor | Glass Bioreactor | Stainless Steel Bioreactor |
Overall Cost | Low initial, High ongoing | Low to medium initial, Low ongoing | High initial, Low ongoing |
Customization | Limited to moderate | Moderate | Extensive |
Cleaning | Generally not required | Autoclavable | CIP/SIP required |
Turnaround | Typically faster | Moderate | Longer due to cleaning and sterilization |
Limit | Solid waste generation | Limited scalability as working volume increases | Less flexible for installation & changeover |
Different Scales of Stirred Tank Bioreactors
Scale is another practical starting point for bioreactor selection. The benchtop bioreactors, pilot-scale bioreactors, and industrial bioreactors serve different purposes within the development and manufacturing pathway.
Benchtop Bioreactor
Early-stage process development
Media and feeding strategy screening
Process parameter optimization
Scale-down modeling in research laboratories
Pilot-Scale Bioreactor
Transfer-ready process
Scale-up key parameter validation
Process robustness and reproducibility testing
Bridge the gap between laboratory research and commercial production
Industrial Bioreactor
Large-scale manufacturing
Stable commercial production
Process reliability, consistency, automation, and production efficiency become major priorities
From research labs to large-scale manufacturing, LAB1ST provides customized bioreactor solutions designed to accelerate cell culture and microbial process development.
Key Takeaways
How to Choose the Right Bioreactor for Your Bioprocess Development?
Start with the organism or cell type. Are you working with shear-tolerant microbes or shear-sensitive mammalian cells? This determines the impeller type, mixing strategy, sparging, and aeration approach.
Evaluate the construction. Do you need the flexibility and rapid turnaround of single-use, or the durability and cost-efficiency of multi-use stainless steel? For early studies where excellent visibility and repeated experimentation are important, a glass bioreactor can be a practical option.
Consider the scale. Are you in early exploration (benchtop), process verification (pilot), or consistent manufacturing (industrial)? Selecting equipment with future development stages in mind can make process transfer easier.
Plan for scalability. LAB1ST bioprocessing platform supports a logical scale-up strategy with consistent geometry and performance characteristics. Contact us to select the right configuration and develop a reliable scale-up pathway.
Frequently Asked Questions
What is the difference between a bioreactor and a fermenter?
The terms are often used interchangeably, but in practice, "fermenter" typically refers to systems designed for microbial cultures (bacteria, yeast, fungi), while "bioreactor" is more commonly used for mammalian cell culture.
Can I use the same stirred tank bioreactor for both microbial and cell culture?
Potentially, but the configuration may need to be changed. Microbial cultures require high-shear mixing and high oxygen transfer rates, while cell cultures need gentle mixing and precise environmental control. Using a system optimized for one application in the other will likely compromise performance.
When should I choose a single-use bioreactor?
Single-use bioreactors are best suited for cell culture applications, multi-product facilities, and environments where fast turnaround and reduced contamination risk are priorities.
What is the typical scale-up pathway from lab to production?
A common pathway moves from benchtop (0.5–10 L) to pilot (10–200 L) to industrial (>200 L). Each step requires verification of critical parameters to ensure consistent performance.
