Single-Use Bioreactors

Single-use bioreactors are used to culture cells in large volumes. In contrast to traditional stainless steel multi-use systems, a plastic bag is used as culture vessel and disposed of after use. By omitting cleaning and sterilization steps that are necessary with multi-use equipment, turn around time between production batches can be considerably reduced. The culture bags are ususally provided sterile, and ready to use, following installation in the bag holder. Connections to gassing and feed lines are established through attached tubings. Sensor ports or integrated single-use sensors allow for process monitoring and control through process analytical technologies (PAT). 

Single-use eliminates the need to clean and autoclave the cell culture vessel and removes the time, labor, expense and environmentally hazardous chemicals associated with this. Several benefits arise from this, including a faster turn-around time between production batches and increased flexibility in process set-up. Traditional stainless steel bioreactors are often bolted in place, and hard-wired to process gasses, water and steam, while single-use bioreactors are often more mobile and arranged on skids. Available sensor ports, feed lines and gassing strategy are determined by the configuration of the single-use disposables and can thus be easily changed and adapted to process needs. 

Single-use bioreactors typically follow a modular design. The actual cell culture vessel is usually a plastic bag containing stirring and gassing elements as well as feed lines and sensor ports. This bag is then installed in a bag holder, providing structural support and heating capabilities. Via a separate control unit, set-points for temperature and gassing can be defined, sensor read-outs are collected and process automation is realized. 

Single-use bioreactors have some inherent advantages such as shortened turn-around times, no need for lengthy cleaning protocols and increased flexibility, however not all processes can benfit from these. Especially for processes with extremely high oxygen demands, requiring increased stirring speeds and high gassing rates or with extreme process conditions in terms of temperature or acidity, conventional stainless steel bioreactors can be a better alternative. Due to the required installation and deinstallation procedures, as well as bag production, shipping and sterilization limitations, the achievable volumes for single-use bioreactors are limited. We believe that productivity and yield can be increased for mammalian cell culture processes through process instensification, eliminating the need for ever lager facilites; however some microbial processes are ususally run in bioreactors with volumes of more than 10m³. 

It is often stated that single-use is more expensive than stainless-steel, but this highly depends on the type of process, process duration and general strategy. Process intensification can significantly reduce cost of goods in single-use processes and the inherent flexibility of single-use bioreactor systems can help to save costs and space as well. The shorter turn-around time can increase overall facility output, another benefit of adopting single-use technology.