Characterization and Engineering Performance of the Allegro™ STR 500 Single-Use Stirred Tank Bioreactor

Stirred tank bioreactors (STRs) have become a popular choice for single-use large scale commercial manufacture of suspension cell lines and therapeutics. Cell culture performance is strongly influenced by the efficiency of mixing to achieve culture homogeneity, supplemented with the effectiveness of gas delivery to support varying oxygen mass transfer coefficient (k_La, O₂) demands. The ability to provide a seamless scale up from a benchtop bioreactor to large scale manufacture requires careful thought in vessel design engineering modeling and computational fluid dynamics, as well as actual engineering studies, and live cell culture run performance evaluations. The Allegro STR bioreactor range has been designed to provide predictable scale-up performance, therefore, the comparison of the mixing and mass transfer capabilities across the bioreactor range can be presented from bioreactor to bioreactor at their specified volumes.

The addition of the Allegro STR 500 bioreactor system unifies the existing Allegro STR family range of bioreactors. The Allegro STR 500 bioreactor maintains scalable engineering performance with the Allegro STR 50, 200, 1000, and 2000 L bioreactors, while leveraging usability and process assurance features that have differentiated Pall’s Allegro STR bioreactor product range from all others in the single-use stirred tank bioreactor market.

As with all Pall’s Allegro STR bioreactors, the Allegro STR 500 single-use bioreactor has been developed to provide excellent mixing performance through a direct drive agitation mechanism, coupled with a large 45° elephant ear bottom-mounted impeller, which generates excellent axial and radial flow inside the reactor, and a novel shaped biocontainer with baffles to maximize culture homogeneity with no dead zones. In addition, the Allegro STR 500 biocontainer features a macro ring sparger to deliver gas directly to the culture fluid interface. The unique seating of the macro sparger below the large elephant ear impeller distributes gas delivery directly through the rotating blades of the impeller to maximize mass transfer, as well as facilitating effective CO₂ stripping. For more demanding high cell density applications, requiring additional carbon dioxide (CO₂) stripping capabilities, an optional open pipe sparger is included.

Engineering performance characterization of the Allegro STR 500 bioreactor, in terms of mixing efficiency, mass gas transfer (oxygen mass transfer and CO₂ stripping efficiency), and temperature control, demonstrates excellent performance at a wide range of agitation speed and these are presented in this application note.

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