August 1, 2006 (Vol. 26, No. 14)
Traditional Reactors Still Favorites for Fermentation and Large-Scale Cell Culture
Increasingly popular single-use bioprocessing systems are undoubtedly taking market share from conventional glass and steel stirred reactors. Disposables are carving their niche in research to pilot-scale cell culture arena but for now, at least, continue to face technological hurdles in the areas of microbial fermentation and large-scale manufacturing of recombinant proteins in mammalian cell culture. In these market sectors the industry still embraces traditional glass and steel stirred tank technology.
With growing emphasis on protein and Mab-based therapeutics in both pharma and biotech, surging interest in cultivating vaccines in cell culture, and a focus on protein biomarkers in drug discovery and diagnostics development, the future remains bright for manufacturers of both traditional and disposable bioprocess systems. An increasingly competitive landscape, however, will continue to put pressure on companies to keep quality high and prices low, while expanding and improving their product lines for broad-based applicability.
Collaborative efforts and innovation will likely drive the development of hybrid systems that exploit the synergies and efficiencies of conventional processing technology as well as single-use reactor vessels and components.
“We are seeing strong interest in traditional bioreactors and fermentors with heightened interest in the area of vaccine production,” says Mike Sattan, director of marketing at New Brunswick Scientific (NBS; www.nbsc.com>), as R&D for developing novel methods for vaccine production in bioreactors heats up.
Another emerging growth market for traditional bioreactor technology is in ethanol production, with R&D funds being earmarked for exploring new strategies for producing ethanol for use as a gasoline additive.
Large-scale protein production in cell culture systems has not demonstrated a notable shift to disposable technology either, observes Sattan, with the exception of growing seed cultures for large-scale tanks in disposable bags, where heightened concerns of contamination often favor disposable vessels for cell culture applications. In the R&D sector, “fermentation has held onto traditional reactor systems,” Sattan adds.
In April, NBS introduced the BioFlo 310 benchtop, autoclavable fermentor/bioreactor, a system designed for flexibility and use in a broad range of applications. The validatable unit allows eight or more external devices, such as analyzers, sensors, pumps, or scales, to be directly connected to the controller for process optimization.
For example, data from YSI’s (www.ysi.com) and Nova’s (www.biomedical.com) on-line biochemistry analyzers can be integrated with the BioFlo 310’s control cascades to assess metabolic activity and automate addition of nutrients and gasses into the vessel.
In addition to pH and dissolved oxygen, monitoring of optical density, CO2, and redox reactions are also available options. The controller simultaneously regulates up to four independent vessels and up to 32 process parameters per vessel. The touchscreen interface offers trend graph capability. Four available vessel sizes range in working volume from 0.6-10.0 L.
NBS recently expanded the capacities of its larger-scale BioFlo Pro line with cell culture bioreactors in volumes up to 300 L and fermentors up to 3,000 L.
Modular System Design
“The industry is moving toward disposables every day,” but there is certainly room in the market for both traditional and disposable technology, and there are hurdles that disposables have not yet overcome in terms of large-scale production, says Stephen Mitchell, president of Appropriate Technical Resources (ATR; www.atrbiotech.com). For modeling of large-scale processes and for scale-up “you are forced to work in the format you will eventually develop the product in,” Mitchell says.
Manufacturers of bioprocess systems will benefit from burgeoning interest in the use of biomaterials, such as corn and sage grass, for products, such as plastics and fuel additives, notes Mitchell.
The newest member of the ATR product line is the Infors Multifors system (a replacement for the Sixfors system) that has a volume range of 80-500 mL. Sold in multiples of two vessels, the Multifors offers users the flexibility to expand the system as needed. Infors plans to develop disposable vessels and components for use with the Multifors.
Also new is the Techfors-S with CIP/SIP capability. It is available with double-jacketed stainless steel vessels in total volumes of 7.5, 15, or 30 L and is designed for transitioning bacterial and cell culture systems from the lab bench to pilot-scale production.
ATR has placed three of its TerraFors systems at beta reference sites for use in bioremediation applications. The units enable in-earth biological modeling in the laboratory. “Solid-state fermentation also has interesting implications for production,” notes Mitchell.
HEL Inc. (www.hel-inc.com) launched the poly-Block multireactor system earlier this year. The poly-Block can accommodate four or eight vessels that operate in parallel with independent temperature, stirring control, and liquid dosing. Customers have the option of glass or autoclavable steel high-pressure vessels in volumes of 1 mL to 250 mL and can choose to add sensors for on-line, real-time monitoring of pH, dissolved oxygen, pressure, or turbidity, for example.
The main advantages of the poly-Block are its cost and flexibility, says Russell Lee, director of sales at HEL. Users can design the system to meet their cost and application needs. Historically, the demand for systems capable of performing automated, parallel processing initiated in the chemistry groups in big pharma, observes Lee, with slow but steady adoption of automated reactor systems in the biotech sector. He believes that the availability of lower cost, modular systems will continue to fuel that trend.
BioXplore (www.bioexplore.net), a subsidiary of HEL, offers the Expert line of autoclavable glass vessels with stainless steel head plates in the 1-L to 2-L range. These systems are designed for applications such as toxicology studies, bioparameter optimization, expression studies of recombinant proteins, and scale-up, according to Lee.
The new kid on the block for Sartorius BBI Systems (www.sartorius.com) is the Biostat Aplus, a benchtop, autoclavable, laboratory fermentor/bioreactor system designed for small-scale protein expression or transitioning from shaker or tissue culture flasks. It features a four-gas mixing system for cell culture or an oxygen enrichment gas mixing system for microbial culture and temperature, dissolved oxygen, pH, and agitation and fill level control.
Available in volumes of 1-, 2-, or 5-L, the Biostat Aplus includes a laptop PC with local control and supervisory process control software, capable of independently handling up to four units.
Sartorius Biosystems is in the process of upgrading its line of bioreactor systems, according to Maik Jornitz, group vp for global product management bioprocess/biosystems. The upgraded Biostat Bplus system includes a range of preconfigured application-based packages, a 1-10-L UniVessel culture vessel, a multifunctional integrated gassing system, and optional redox and turbidity monitoring.
Jornitz reports continued strong demand from the fermentation sector, with a trend toward standardization and off-the-shelf, modular systems rather than the custom-engineered approach favored in the past for systems up to about 500 L. Standardization will help meet the industry’s demand for faster delivery times and reduced capital expenditures.
The focus is now on an assemble-to-order approach rather than a build-to-order mentality, says Jornitz.
Trend toward Standardization
Earlier this year, Applikon (www.applikonbio.com) introduced the iControl, an in-house designed, standardized controller built on an industrial platform with preconfigured application packages. The iControl offers the option of an Allen Bradley, Siemens, or Delta V programmable logic controller, Wago FieldBus I/O modules, and a touchscreen interface, as well as control capability for pH, dissolved oxygen, weight, temperature, and agitation.
The main advantages of the controller are its ease of use and flexibility, according to Howard Weber, director of sales and marketing at Applikon. “Engineers like the iControl for its industrial platform, and scientists appreciate its ease of use and expandabilityand you don’t need engineers to configure the unit. The controller can operate SIP units and up to four autoclavable/single-use bioreactors,” Weber says. Design standardization simplifies validation, process transfer, and scale-up, he adds.
Christian Julien, a consultant in the bioprocessing industry, describes an emerging trend in research and process development toward the use of microbioreactors for scale-down modeling, process design, and screening applications in miniaturized 1-12-mL formats. This represents one potential growth area in which innovation and combinations of single-use and traditional technologies could prove advantageous.
In November, Applikon launched the -24 Micro Bioreactor, a high-throughput fermentation and cell culture device that incorporates 24 microbioreactors on a single disposable cassette with individualized control of temperature, pH, and dissolved oxygen via a laptop computer.
“Disposable reactors will cannabilize to a certain degree the research and preclinical market within the industry,” says Jornitz. However, both small-scale glass autoclavable vessels and single-use reactors will continue to play an important role, he adds. Whereas industrial users may gravitate more toward presterilized, disposable systems, researchers in academia tend to prefer equipment that can be cleaned and reused.
The challenges single-use bioreactors and fermentors face when volumes rise to 1,000 to 2,000 L or higher are more physical than technical, explains George Koch, CSO at Diosynth Biotechnology (www.diosynthbiotechnology.com). Above about 500 L, reactor bags require a support system and become more difficult to move around.
“Filling bags of that size with medium is more of an art than a science,” says Koch. He is confident, though, that the disposables industry will solve the problem of incomplete bag deployment on filling, overcoming a key challenge in applying disposable technology to large-scale bioprocessing.
Diosynth Biotechnology, a contract manufacturing organization, currently manufactures four commercial proteins at its facilities in Research Triangle Park, NC, and Oss, The Netherlands, all in traditional steel tank systems. Diosynth has switched to disposable bags for buffer preparation and storage and uses a variety of disposable components for sampling of cultures, for example to monitor stability over time. Some of the company’s customers are using disposable systems, including hollow fiber bioreactors, to grow seed cultures to feed the tanks.
Although the fact that disposable technology can reduce capital investment and construction costs and be up and running more quickly than traditional production systems “are very legitimate arguments made by disposables manufacturers,” Koch says. Based on his experience in the contract industry, however, he says, “I think customers will continue to look more favorably on traditional materials, such as steel, for now.”
The trend toward disposables in the U.S. market is not mirrored in Europe, notes William Bartley, bioreactor product manager at Bellco Glass (www.bellcoglass.com). “The mentality is different,” he says. Their view of waste disposal differs.
Bartley predicts a shift in thinking over the next decade toward the concept of disposable glass. The cost of glassware today is only a little higher than that of disposable plastics, observes Bartley, and glass is recyclable. An emphasis on recycling of glassware in the future could support a broader view of glass as a disposable product. To meet current market needs, Bellco will continue to offer and improve on its line of classic stirred tank reactors and also plans to introduce a family of disposable bioreactors and components.
Julien describes the shift toward disposable vessels for small- to pilot-scale cell culture as a classic example of technology displacement. Single-use technologies have evolved from system components to their use as packaging materials for bioprocess containers, to the development of single-use mixing and bioreactor systems (pioneered by Wave Biotech, LLC; www.wavebiotech.com), to current efforts to expand their integration with sensor technology and control systems and to design internal mixing technology.
As the manufacturers of traditional bioreactor/fermentor technology have begun to introduce their own lines of disposable components and systems, Julien sees these companies taking a more prominent role in the future in the disposables sector by funneling internal R&D funds into single-use technology development and initiating strategic alliances with smaller innovators.
“I think the future holds promise for the integration of single-use and traditional technologies,” says Julien. This could help alleviate some of the cost pressure on manufacturers of conventional systems.
With biogeneric compounds ready to challenge off-patent drugs, competition will increase, adding to current cost pressures and driving greater integration of single-use and traditional technologies, in Julien’s view.