Hugely popular
Parallel systems for the perfect bioprocess

Bioreactors and fermenters are items that no biotech laboratory can do without. Even on a small-scale operation, both are essential. This is driven, on the one hand, by the current acceleration in process development and, on the other hand, by the desire to be able to perform several tests at the same time. It is no surprise then that parallelization and miniaturization are two concepts that are currently hugely popular. To coincide with Biotechnica, this survey presents a host of exciting innovations.

Particularly in the field of production equipment, the trend towards high-quality cell culture systems continues unabated,” explains Bernd-Ulrich Wilhelm from Sartorius BBI Systems. Just recently Boehringer Ingelheim has doubled production capacity, and Roche in Penzberg has just laid the foundations for a new plant (see page 10). Similarly, the giants of the industry—like Applikon, Bioengineering and B. Braun Biotech—have reported increased demand for bioreactors suitable for cultivating animal cell cultures. However, not just in production—manufacturers also note a clear switch to cell cultures in the laboratory environment as well.

Parallel and flexible systems
Unlike the workhorses of conventional fermentation, microorganisms like Escherichia Coli or Bacillus Subtilis, where the trick is to optimize complex processes, bioprocess engineers have been battling to optimize the space-time yield on slow-growing animal cultures amid the ever-present risk of germinal contamination. Wilhelm also mentions reliability of sterility and longevity of the materials as two fundamental factors particularly important for users.
This is compounded by the fact that, whether in terms of media composition, screening for mutants or optimizing strains, anyone developing bioprocesses is forced to test numerous different approaches with continuously changing settings before eventually finding the right parameters.
“Parallelism is a very important requirement in the development of bioprocess engineering,” confirms Dietrich Oberst, Subsidiary Manager at New Brunswick Science for Germany, Switzerland and Austria. This applies to both the number of reactors and the control mechanisms. The company is a specialist in the field of reactors for process development and pilot-size processes, and has developed the software package Biocommand for parallel controlling of several reactors. The software uses an AFS interface to control up to eight bioreactors and can distribute information via a LAN to different workstations.
Flexibility is also an important quality when it comes to the chosen culture method. “We need the systems that are capable to work with different cell types,” explains Oberst. The modular CelliGen Plus system allows users to switch between different suspension, micro-carrier and fixed bed applications. Then there is the patented basket impeller fixed bed system for cultivating adherent-growth and suspension cells. The shear stress free ventilation system features a centrally positioned impeller rotor that generates a vacuum forcing the medium to undergo continuous, looping circulation motion inside the reactor. The hollow fiber bioreactors from the Berlin-based company Probiogen are an interesting approach to the low-volume production of antibodies
and enzymes, which are secreted from
the production cells into the medium. Due to the tube-like characteristics of the fibers, nutrients like glucose and oxygen can be fed into the cells while waste products like carbon dioxide and water are removed. The cells produce highly concentrated cell protrusions that can be easily cut off.
Similarly to New Brunswick, Braun Biotech also puts increasing effort into the use of disposable components in existing systems. Initial success has been reported “in the field of disposable components for perfusion processes with animal cells”.
Recently, the US-Americans have launched Fibrastage, a “ready to use” disposable system for high cell densities that dramatically reduces the requirements for cylindrical bottles. A 500 ml bottle contains 10 g of fibracell disks and makes it possible to have the same cell density as ten cylindrical bottles.
“Another important aspect is low commitment of laboratory capacities, both in terms of space and personnel,” says Wilhelm. This explains the current trend for systems that fit on the top of a laboratory table.
Dasgip, a company based in Jülich, Germany, offers two corresponding cultivation systems: Cellferm-Pro for the cultivation of mammal and insect cells, and Fedbatch for microbial fermentation. “Our cultivation systems close the gap between instrument-controlled fermenters and simple, uncontrolled cultivation vessels,” illustrates Dr. Matthias Arnold, Technical Director of Dasgip. The cell culture system Cellferm-Pro has been recently awarded the “red dot award” by the Design Zentrum Nordrhein-Westfalen (Design Center of Northrhine-Westfalia) allowing to use the red dot symbol—the coveted quality mark for superior industrial design. The Jülich-based company not only believes in parallelization, but also in modularization: the metering units, pumps, measuring modules and gassing modules and the mini-format cultivation vessels for suspension cultures and fixed bed cultures can be combined as required, allowing so to create systems that “grow with the job”. Another topic for Dasgip is the optimization of existing processes, which need to be broken back down from large-scale fermenters to handheld size. “With the aid of our cultivation systems, production processes like vaccine production and fine chemistry have been successfully miniaturized, optimized for parallelized production methods and then scaled back up to full production size,” explains Arnold.
Miniaturized high-throughput systems
Although Dasgip systems are already quite small, various companies are already working on ways to develop systems for high-throughput fermentation, which operate along similar lines to the high-throughput screening systems. The most advanced of these projects is being run by the Degussa Project House Proferm. Together with Prof. Jochen Büchs from RWTH Aachen, the Project House team has modified a robot system for high-throughput screening of biocatalysts to allow it to be used for micro-scale fermentation in future applications. The central element in this system are the microtiter plates which are transported via a robotic arm to all the different units. As 768 cultivation experiments can be run at the same time, the most suitable microorganisms for any given fermentation process and the best possible development conditions can be found very quickly.
The chair for bioprocess engineering at the Technical University of Munich has taken a big step towards miniaturization. Working together with the Laboratory Equipment Division (previously H+P Labortechnik) of Thermo Electron Corporation, Prof. Dirk Weuster-Botz and his team of bioprocess engineers have developed a shoebox-sized bioreactor block containing 48 parallel reaction vessels with mini-agitators, each of which has a capacity of just 10 ml, which it is hoped to open up the whole field of bioprocess development. The equipment hardware, i.e. the reactor block with temperature control unit, return flow cooler and drive mechanism for the agitators, comes from Thermo Electron, who in the past has specialized in magnetic agitators and shakers, as well as sterilizers and steam generators. “Our core competence lies in the development of reaction blocks,” states Michael Fischer, Marketing Manager & Business Unit Manager at Varioklav Steam Sterilizers and Variomag Magnetic Products. An important detail in the high-throughput unit is the contactless optical sensor system supplied by the specialist company Presens in Regensburg, which is used to measure pH levels, carbon dioxide and oxygen concentrations. The bioreactor—which will be shown to the public for the first time at this year’s Biotechnica—is intended to open up new avenues into new market segments. “We believe in miniaturization,” insists Mr Fischer.