SIMILARITY TO STAINLESS
What has led to the rapid adoption of the large-scale bioreactors over the last two years? Jon Reid's view is that biopharmaceutical
manufacturing is a conservative market and is used to the stainless-steel configuration. The more similar the bioreactor configuration,
instrumentation, and control systems are to the stainless-steel bioreactor, the greater will be the acceptance. The ready
acceptance of the SUB and XDR may be because their height to diameter ratios are similar to their stainless-steel counterparts,
and both use conventional instrumentation. The SUB differs from the XDR in that the SUB has a mechanically linked agitator
compared to the XDR's magnetically coupled unit. The mechanically coupled agitator provides scope for precise positioning
of the impellor and the option to go for different designs in the drive to improve heat and mass transfer.
THE FORSEEABLE FUTURE
So what's important from the user's perspective and where are the challenges? According to a recent presentation at the ISPE
2008 Conference on Manufacturing Excellence by Dave Wareheim, engineering fellow at Centocor, users want similar geometries
to stainless-steel bioreactors with good mixing, gas distribution, and heating and cooling.
To date, disposable bioreactors have primarily been used in cell cultures. The shift in their usage in microbial or yeast
systems will not be easy and will require significant technical advances. Going forward, bioreactor volume will probably not
increase much above 2,000 L; both Xcellerex and Thermo Fisher have stated that this is the limit for the foreseeable future.
The maximum working volume for the Wave is 500 L. Technical improvements are required in mixing, sparging, and heating and
cooling of the current models. These are essential to meet the demands of the high-titer processes, especially at larger volumes.
At present, the instrumentation used is based on conventional probes. It is expected that these will be replaced by disposable
sensors. There will be a large number of new entrants into this market followed by a consolidation. Disposable bioreactors
will become the dominant technology in biomanufacturing operations. Their adoption is being driven by two trends—reduced manufacturing
costs and the development of high-titer processes. Given the conservative nature of our industry and the requirements of scale-up
and scale-down, disposable technologies that mimic the conventional stainless-steel bioreactor will be most readily adopted.
Andrew Sinclair is the managing director at Biopharm Services, Chesham, Bucks, UK, +44 (0) 1494 793 243, email@example.com