Klapan, A., Stibane, D., Wurm, C. l Bioprocessing Solutions

How to Choose the Right Bioreactor for Your Research

Choosing the right bioreactor is a critical step in ensuring the success of any research project in biotechnology. Whether you are cultivating mammalian cells, microorganisms, or photosynthetic organisms like algae, the type of bioreactor you select will influence everything from productivity to scalability. With various bioreactor types available on the market—ranging from benchtop models to industrial-scale systems—making the right decision can seem overwhelming. However, by evaluating your process needs, operational scale, and desired outcomes, you can choose a bioreactor that fits your research goals. In this article, we’ll walk you through the essential factors to consider when selecting a bioreactor, such as scale, material, feeding strategies, and more. Whether you’re working in a small laboratory or planning for industrial-scale production, this guide should help you make the right choice.

TYPES OF BIOREACTORS AND THEIR APPLICATIONS

Before diving into the specific features of bioreactors, it’s important to understand the various types and their applications. Each type serves a specific purpose and is suited to different scales, organisms, and research goals.

1. Lab-scale vs. pilot-scale vs. industrial-scale bioreactors

The first major decision when selecting a bioreactor is determining the appropriate scale for your operation. Whether you are conducting preliminary research, scaling up production, or optimizing an industrial process, there is a bioreactor designed for each level.

Microbioreactors: Small, high-throughput systems with volumes typically less than 1 milliliter. They allow simultaneous testing of multiple conditions with minimal resources, making them ideal for early-stage screenings and rapid data collection.
Lab-scale bioreactors: These are small systems, typically ranging from 0.5–10 liters in capacity. Lab-scale bioreactors are perfect for early-stage experiments, process optimization, or academic research where researchers are exploring basic biological processes or testing novel approaches. They allow researchers to control conditions on a smaller scale while keeping costs low.
Pilot-scale bioreactors: Pilot-scale bioreactors range between 10 to 100 liters and are used when a process developed in the lab needs to be scaled up for further testing or production. This scale is ideal for optimizing parameters that will later be applied to industrial-scale production. Pilot-scale systems help bridge the gap between laboratory research and commercial production by allowing researchers to troubleshoot and fine-tune the process on a medium scale.
Industrial-scale bioreactors: With capacities greater than 100 liters, industrial-scale bioreactors are designed for mass production. These systems are typically used in industries such as pharmaceuticals, biofuels, food, and beverages. Industrial bioreactors offer robust monitoring and control capabilities and are equipped to handle the demands of continuous or batch production on a large scale.

2. Stirred tank (STR), rocking motion, air lift, and fixed bed bioreactors

Bioreactors can also be classified based on their mixing and aeration mechanisms.

Stirred tank reactors (STR): A gold standard, common in research and industrial settings, STRs use impellers for efficient mixing and gas distribution. They are suitable for a wide range of applications, including cell cultures and microbial fermentation.
Rocking motion bioreactors: Ideal for sensitive cell cultures, these bioreactors use a rocking motion to mix the culture gently, making them suitable for mammalian and other shear-sensitive cells. However, they often lack sophisticated control systems, limiting process control.
Air lift bioreactors: In these very specialized systems, mixing is achieved by injecting air or gas into the culture medium, creating circulation through air bubbles. Air lift bioreactors are energy-efficient and commonly used for processes where low shear stress is critical, such as algae or plant cell cultures.
Fixed bed bioreactors: These bioreactors contain immobilized cells or enzymes within a fixed structure. Fixed bed bioreactors are often used for continuous processes or applications where high cell density is desired, such as wastewater treatment or biocatalysis.

3. Single-use vs. multi-use bioreactors

Bioreactors are also categorized as single- or multi-use, each with unique impacts on cost, operational flexibility and sterility. Both available across scales, from lab to industrial, the choice often depends on specific process and/or research needs.

Single-use bioreactors: Made from disposable plastic, single-use bioreactors prioritize sterility and quick setup, eliminating the need for cleaning and reducing contamination risk. However, they are less sustainable, generate more waste, and typically have higher operating costs over time. Commonly used in regulated environments, such as clinical trials and personalized medicine, single-use bioreactors might be preferred when contamination control is critical.
Multi-use bioreactors: Constructed from stainless steel or glass, multi-use bioreactors are reusable, more sustainable, and cost-effective over time. While requiring cleaning and sterilization, they offer greater flexibility for complex, high-throughput operations. Suitable for both laboratory and industrial scales, these systems are widely used in various applications such as the production of vaccines, enzymes, and biofuels. Their long-term durability and adaptability make them invaluable in many biotechnological processes.

4. Cell culture bioreactors vs. fermenters

Another critical consideration when selecting a bioreactor is the type of organisms being cultivated. The choice between cell culture bioreactors vs. fermenters will depend on whether you are working with delicate mammalian cells or microorganisms.

Cell culture bioreactors: These bioreactors are optimized for the cultivation of mammalian, insect, or plant cells. Because these cells are more fragile, cell culture bioreactors feature gentle mixing and low gas flow rates to minimize shear stress and avoid cell damage. Pitched-blade impellers are commonly used in cell culture bioreactors to create smooth, low-turbulence mixing.
Use case: Cell culture bioreactors are utilized in various industries for producing mammalian cells, including pharmaceuticals for therapeutic proteins, vaccines, and monoclonal antibodies, as well as in sectors such as cultivated meats, where maintaining cell viability is crucial.
Fermenters: These bioreactors are specifically designed for microbial fermentation processes. They are equipped with high gas flow rates and powerful impellers (such as Rushton impellers) that create vigorous mixing to ensure the even distribution of gases and nutrients. Fermenters are ideal for cultivating robust organisms like bacteria, yeast, or fungi, which can withstand more intense conditions than mammalian cells.
Use case: Fermenters are primarily used to grow yeast, bacteria, and fungi. They are widely used in industrial biotechnology for producing enzymes, ethanol, and various metabolites, as well as in pharmaceutical industries for antibiotics. While industrial biotech is a common use case, there are many other applications as well.

5. Photobioreactors

As a specialized type of stirred-tank reactor (STR), photobioreactors provide the ideal environment for photosynthetic organisms, like algae. These bioreactors are designed to optimize light exposure while maintaining control over temperature, gas exchange, and nutrient supply.

Additionally, there are specialized photobioreactors that are not based on STR, offering a range of configurations optimized for various applications. These include tubular photobioreactors, flat-panel photobioreactors, and hybrid designs, each tailored to enhance specific aspects of the cultivation process, such as light distribution, scalability, and efficiency.

Use case: Photobioreactors are critical in research on carbon capture, biofuel development, and the production of nutraceuticals from algae. Their design ensures that light can penetrate the culture evenly, allowing for efficient photosynthesis.

6. Batch, fed-batch, and continuous bioreactors

Though not types of bioreactors themselves, feeding strategies determine how nutrients are supplied to the culture during the growth process. Understanding these strategies is important when selecting a bioreactor that matches specific process needs.

Batch bioreactors: In batch processes, all nutrients are supplied at the start, and the culture is allowed to grow without further input until it reaches the end of the growth cycle. Batch systems are simple and easy to manage but may limit productivity over longer periods.
Fed-batch bioreactors: In fed-batch systems, fresh nutrients are periodically added during the growth process, allowing the culture to remain in the productive phase for a longer time. This strategy is commonly used in processes that benefit from prolonged growth, such as protein production.
Continuous bioreactors: Continuous systems involve the constant addition of fresh medium while simultaneously removing spent culture, allowing the process to maintain steady-state conditions for extended periods. Continuous bioreactors are highly efficient for long-term production and are frequently used in large-scale industrial operations.

KEY FACTORS TO CONSIDER WHEN CHOOSING A BIOREACTOR

Now that we’ve discussed the different types of bioreactors and feeding strategies, let's look at the key factors that should guide your selection process.

1. Process needs and scale

The first consideration when choosing a bioreactor is determining the scale of your research or production process. Are you conducting experiments on a small scale, or are you planning for full-scale production? The size of the bioreactor must align with your goals, as well as the expected volumes of medium and product. For small-scale academic research, a lab-scale bioreactor may be ideal, allowing you to control all parameters at a manageable scale. However, for projects transitioning to commercial production, pilot-scale or industrial-scale bioreactors provide the scalability necessary for larger outputs.

2. Type of cells or organisms

The type of cells or organisms you are working with plays a critical role in determining which bioreactor will be most suitable. Mammalian cells, for example, require a bioreactor that offers gentle agitation, controlled oxygenation, and precise pH regulation to ensure cell viability. On the other hand, microorganisms such as bacteria and yeast can tolerate more aggressive mixing and higher oxygen levels. Choosing a bioreactor designed specifically for your organism type will help ensure optimal growth conditions and productivity.

3. Oxygen requirements

The gas exchange system in your bioreactor will have a direct impact on the growth and metabolism of your culture. Many processes, particularly those involving aerobic organisms, require high oxygen levels, which are supplied through spargers or surface aeration systems. For processes involving delicate cells, it’s essential to select a bioreactor that provides efficient oxygen transfer without creating excessive shear stress or foam formation. Efficient gas exchange ensures that your culture receives the oxygen it needs while preventing the accumulation of offgas.

4. Sensors and monitoring

Modern bioreactors come equipped with a range of sensors that monitor critical parameters such as temperature, pH, dissolved oxygen, and nutrient levels in real-time. These sensors allow researchers to adjust conditions as needed to maintain optimal growth environments.
If your research requires tight control over environmental conditions, consider choosing a bioreactor with advanced monitoring and control systems. This can significantly improve reproducibility and reduce the risk of variability in your experiments.

5. Flexibility and modularity

Choosing a modular bioreactor that offers flexibility can be advantageous, particularly if your research needs evolve over time. Many bioreactors today allow for adjustments in vessel size, feeding strategies, and control systems to accommodate a variety of applications. This flexibility makes it easier to scale up your research or shift focus to different organisms or processes without investing in entirely new equipment.

6. Costs and ease of operation

Cost is a critical factor, especially when evaluating long-term expenses. While single-use bioreactors may have lower initial costs, multi-use reactors are generally more cost-effective over their lifetime, as they reduce recurring expenses associated with disposables.
Additionally, ease of operation is important; a bioreactor with user-friendly features and straightforward maintenance requirements can streamline workflows, reduce training needs, and minimize the potential for operator errors.

CONCLUSION

Choosing the right bioreactor involves more than just picking a system that fits your budget. It’s a decision that will impact the scalability, productivity, and efficiency of your research. By considering the type of organism you’re working with, your operational scale, the feeding strategies that fit your process, and the level of control and monitoring required, you can make an informed choice that enhances your bioprocessing outcomes.

In bioprocessing, the right bioreactor is a powerful tool that not only supports your current research but also opens the door to future possibilities. Opting for a flexible, sustainable, and cost-effective solution, such as a multi-use STR, can provide lasting value and adaptability as your research evolves. Consulting with bioreactor manufacturers and application specialists can help determine the optimal system for your specific needs.

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