The Rise of Single-use Bioreactors: Why make the Switch?

The single-use bioreactor market generated $202.5 million last year and researchers estimate it will see another 18.4 percent increase in 2019, reaching $470.9 million. Sixty-six percent of pharmaceutical companies are now preferring this disposable product. What are the advantages of single-use bioreactor bags?

Rockers Vs. Stirrers

Single-use bioreactors are bioreactors that use a disposable bag instead of a culture vessel made of stainless steel or glass. Storage and cultivation bags are the most common. Pharmaceutical companies use single-use bioreactors for media and buffer preparation, cell harvesting, filtration, purification, and virus inactivation. The bags are made of multilayer polymer films and arrive gamma-sterilized from suppliers. The lining of the bioreactor bag that comes in contact with the cell culture is typically polyethylene. The bag is then encased in a more sturdy structure, typically a rocker, cuboid, or steel cylinder.

There are two main types of single-use bioreactors: stirrers and rockers. As the name implies, stirrers mimic conventional bioreactors with a stirring mechanism integrated into the disposable unit. The stirrer is connected to a drive either mechanically or magnetically. The bag and the stirrer are both pre-sterilized. Rockers use a rocking motion to agitate and mix the medium.

Advantages of Single-Use Bioreactors

One of the biggest advantages of single-use bioreactors is the flexibility they allow manufacturers. One of the main culprits in downtime is preparing the bioreactor in the upstream process. Single-use bioreactors drastically decrease the time spent preparing the bioreactor for the subsequent batch. 

A line changeover using single-use bioreactors takes on the order of two hours; with a stainless-steel bioreactor it can take six to 10 hours for the same product, and three weeks for a full product changeover. For manufacturers using a hybrid system - i.e., one that uses single-use systems in the upstream process and stainless-steel systems in the downstream process, the changeover time could be cut to two weeks. However, if the manufacturing line is composed of all single-use components, including filters, bags, and connectors, the total time for product changeover can be as fast as 48 hours. Reducing downtime from two to three weeks to just 48 hours can dramatically impact a company's output.

Another advantage to single-use bioreactors is their ability to scale from prototype to production. Bags currently range in volume from less than 1 liter up to 2,000 liters. While challenges in the scaleup process remain, stemming from larger volumes can include retaining the adequate geometry, tip speed, and power input per volume. Scientists can overcome this challenge by applying a large amount of torque to the stirrer and installing a new drive assembly for the mixing technology inside the bag. However, there is some debate over the quality of the end product when volumes are either extremely large or small.

The following list highlights the main advantages of using single-use bioreactors:

• No cleaning process, eliminating validation issues.
• Decreased downtime and turnaround time.
• Reduces the risk of cross-contamination.
• Decreases operating costs and capital investment, including utilities, space, and labor requirements.
• Simple installation
• Single-use bags are scalable; able to adjust to different volumes.

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Conclusion

A key future development in single-use bioreactor technology is in refining the scaleup processes of single-use bioreactors from very small to very large volumes. Despite these challenges, the single-use bioreactor market segment is expected to expand dramatically in the coming years. As with many new technologies, time will improve design, control, data logging, and automation levels.