Guidelines for Avoiding Pits in Bioreactors: Incorrect sterilization parameters at 1 ℃ and incorrect selection of stirring blades can result in millions of losses per minute! (including 10 key details)
As the core equipment of biotechnology, the production and operation details of bioreactors directly affect production efficiency and product quality. Bailun has summarized ten key details based on the latest practice:
1. The selection of reactors should be adapted to the process requirements and the type of reactor should be selected based on the characteristics of the biological system: mammalian cells require low shear design (such as air lift reactors), while microbial fermentation requires high dissolved oxygen configuration (such as stirred tank reactors).
Disposable reactors (SUB) can shorten project cycles, while stainless steel reactors are suitable for long-term continuous production, requiring comprehensive consideration of cost and cleanliness validation requirements.
2. In terms of material selection and aseptic design, 316L stainless steel or borosilicate glass is used to ensure corrosion resistance, and PTFE material is required for sealing to prevent leakage.
Integrate CIP/SIP system (cleaning and steam sterilization) during design to prevent contamination through sterile boundaries (such as plastic trays) and positive pressure operation.
3. The design of the mixing system and shear force control mixer needs to balance mixing efficiency and shear damage: mammalian cell culture uses inclined blades or magnetic stirring, while microbial fermentation uses high-speed turbine stirring.
4. Multi parameter sensing and automatic control require the integration of pH probes, dissolved oxygen sensors, and temperature probes to monitor the environment in real-time, and achieve automated regulation through SCADA systems.
For example, an oxygen probe is used in conjunction with a jet to dynamically adjust dissolved oxygen, and an overpressure valve ensures operational safety.
5. Precise control of temperature and pH using jacket heat exchange devices or external circulating water systems for temperature control (± 0.5 ℃ error). PH control requires the configuration of an acid-base pump and buffer storage tank. Mammalian cells typically maintain a pH of 7.0-7.4, while yeast fermentation requires a lower pH.
6. Optimization of dissolved oxygen transfer efficiency in microbial reactors, where the aperture and layout of air distributors affect the dissolved oxygen rate (kLa value).
For example, Escherichia coli fermentation requires maintaining a dissolved oxygen saturation of 30% -50%, which can be optimized through gas-liquid mixing (such as membrane aeration) to increase production capacity.
7. To establish a pollution prevention and control system, steam sterilization (SIP) is required before operation. The inoculation port should be designed with a sterile membrane, and a safe sampler should be used for sampling to avoid dead volume pollution.
Regular replacement of filters (such as 0.2 μ m sterilization filter cartridges) and monitoring of biological load are required.
8. Optimize the culture medium and improve the inoculation density of mammalian cells by controlling it at 0.5-1 × 10 ^ 6 cells/mL, and initiate fermentation with Escherichia coli OD600=0.1.
It is necessary to adopt a batch feeding strategy to prolong the logarithmic growth period and avoid the inhibition of metabolic byproducts.
When scaling up the mass transfer and shear equilibrium of the amplification process, it is necessary to solve the problems of oxygen transfer limitation and uneven distribution of shear force.
For example, using computational fluid dynamics (CFD) simulation to optimize stirring parameters and ensure consistent volume dissolved oxygen coefficient (kLa).
10. Ensure that waste disposal and environmental safety are equipped with waste liquid collection systems (such as Allegro MVP virus removal filtration), and that fermentation exhaust is condensed to reduce volatile emissions.
