Bioreactor Design and Operation
Expert-defined terms from the Certified Specialist Programme in Cell Culture course at LearnUNI. Free to read, free to share, paired with a professional course.
Alamethicin – peptide used as a permeability enhancer in cell‑free extrac… #
It facilitates substrate entry in bioreactor assays. Practical use in enzyme production systems; however, excess can compromise cell viability.
Alternating‑Current (AC) Power Supply – provides stable electricity to bi… #
Consistent power reduces fluctuations in temperature and agitation. Practical application in large‑scale facilities; challenges involve harmonics affecting sensor accuracy.
Amperometric Sensor – electrochemical detector for metabolites such as gl… #
Allows real‑time monitoring of substrate consumption. Example: on‑line glucose monitoring in perfusion bioreactors. Calibration drift and fouling are common challenges.
Batch Culture – closed‑system operation where all nutrients are added at… #
Simple to implement and useful for pilot studies. Example: production of viral vectors in a 5‑L shake flask scaled to batch bioreactor. Limitations include low productivity and nutrient depletion.
Bioreactor – vessel that provides controlled environment for cell growth;… #
Designs include stirred‑tank, wave, and hollow‑fiber. Enables precise regulation of temperature, pH, dissolved oxygen, and agitation. Challenges encompass scale‑up, sterility, and cost.
Bioprocess – series of operations that transform raw materials into biolo… #
Includes cell culture, purification, and formulation. Example: monoclonal antibody production from CHO cells. Integration of process analytics is essential for consistency.
Bioreactor Control System – hardware and software that regulate process p… #
Provides feedback loops for temperature, pH, DO, and agitation. Example: PID controller maintaining DO at 40% air saturation. Complexity increases with multi‑parameter strategies and sensor redundancy.
Bioreactor Scale‑Up – translation of laboratory conditions to larger volu… #
Uses dimensionless numbers such as Reynolds and Damköhler to preserve hydrodynamics. Practical challenge: maintaining cell‑specific productivity while avoiding oxygen limitation.
Bioreactor Scale‑Down – intentional creation of non‑ideal conditions to s… #
Used to model large‑scale gradients in laboratory reactors. Example: oscillating pH in a 2‑L vessel to emulate scale‑up gradients. Provides insight for robust strain engineering.
Bubble Column – gas‑liquid contactor without mechanical agitators; relate… #
Provides low shear environment suitable for shear‑sensitive cells. Example: production of recombinant proteins in yeast. Limitations include poor mixing at high viscosities.
Capillary Bioreactor – microfluidic device with narrow channels for high‑… #
Enables precise control of shear and nutrient gradients. Used for stem cell differentiation studies. Fabrication complexity and limited volume are challenges.
Carbon Dioxide (CO₂) Control – regulation of dissolved CO₂ to maintain pH… #
CO₂ removal is critical in mammalian cultures to prevent acidification. Example: using a CO₂ scrubber in a perfusion system. Over‑control can cause alkalosis.
Cathodic Protection – technique to prevent corrosion of metal bioreactor… #
Extends lifespan of stainless‑steel vessels. Implementation requires careful material selection and monitoring.
Cell Line Development – process of generating stable, high‑producing cell… #
Critical upstream step for biopharmaceuticals. Example: DHFR‑amplified CHO cells for monoclonal antibodies. Genetic instability and clonal variation are ongoing challenges.
Closed‑Loop Control – feedback system where sensor data directly adjusts… #
Maintains setpoints for pH, DO, temperature. Example: automatic base addition to keep pH at 7.2. Requires reliable sensors and robust algorithms.
Continuous Culture – operation where fresh medium is continuously added a… #
Provides steady‑state conditions and high productivity. Example: perfusion of CHO cells at 0.03 h⁻¹ dilution rate. Challenges include cell retention device fouling and stability of product quality.
Cryopreservation – storage of cells at ultra‑low temperatures for later u… #
Enables banking of master cell banks. Example: freezing CHO cells in 10% DMSO with controlled‑rate freezer. Ice crystal formation and post‑thaw viability are key concerns.
Dead‑Zone – region within a bioreactor where mixing is insufficient; rela… #
Leads to gradients in nutrients and waste products. Identified by CFD or tracer studies. Design modifications such as baffle placement can mitigate dead‑zones.
Design of Experiments (DoE) – systematic approach to explore factor inter… #
Used to optimize agitation speed, aeration rate, and temperature. Example: a 2‑level full factorial for three parameters in a 2‑L bioreactor. Requires statistical expertise and adequate replication.
Downstream Processing – purification steps after bioreactor harvest; rela… #
Includes clarification, capture, polishing, and formulation. Example: Protein A chromatography for antibody purification. Integration with upstream influences overall yield and cost.
Dynamic Light Scattering (DLS) – analytical technique for particle size m… #
Used to monitor aggregate formation in protein‑producing bioreactors. Example: detecting antibody aggregates during fed‑batch. Requires sample preparation and can be interfered with by high turbidity.
Electronically Controlled Valve – actuator that regulates gas or liquid f… #
Enables precise aeration and feed control. Example: proportional valve adjusting air flow to maintain DO setpoint. Valve wear and response lag must be addressed.
Enzyme‑Linked Immunosorbent Assay (ELISA) – quantitative assay for produc… #
Provides on‑line or at‑line monitoring of monoclonal antibodies. Example: on‑line ELISA integrated with sampling robot. Time delay and reagent cost are practical considerations.
Fed‑Batch Culture – operation where nutrients are added incrementally; re… #
Increases cell density and product titer while avoiding substrate inhibition. Example: glucose‑controlled feed maintaining specific growth rate of 0.02 h⁻¹. Feed strategy optimization is critical to avoid overflow metabolism.
Fluid Dynamics – study of liquid flow behavior inside bioreactors; relate… #
Determines mixing time, shear stress, and mass transfer. CFD simulations help predict performance. Challenges include accurately modeling non‑Newtonian media.
Gas Sparger – device that introduces gas bubbles into the liquid phase; r… #
Influences bubble size distribution and mass transfer coefficient (kLa). Example: stainless‑steel sparger delivering air at 0.5 vvm. Clogging and uneven distribution can impair performance.
Hollow‑Fiber Bioreactor – perfusion system using semi‑permeable fibers; r… #
Provides high cell densities with continuous product harvest. Example: 10‑L hollow‑fiber cartridge for recombinant protein. Fiber fouling and shear control are technical hurdles.
Hydrodynamic Shear – mechanical force generated by fluid movement; relate… #
Impacts cell viability, especially for suspension‑grown mammalian cells. Example: shear stress of 0.2 Pa in a stirred‑tank reactor with Rushton impeller. Balancing mixing and cell protection is a design trade‑off.
Immobilized Cell Reactor – system where cells are fixed on a support matr… #
Enables reuse of cells and simplifies product separation. Example: alginate‑encapsulated yeast for ethanol production. Mass transfer limitations and bead degradation must be managed.
In‑Process Control (IPC) – real‑time monitoring and adjustment of critica… #
Ensures product quality and reduces batch failures. Example: on‑line Raman spectroscopy tracking metabolite profiles. Integration with control loops requires robust data handling.
Inert Gas Blanket – protective layer of nitrogen or argon over liquid to… #
Used for oxygen‑sensitive cultures such as anaerobes. Example: nitrogen overlay in a 3‑L fermenter. Maintaining constant pressure and avoiding contamination are challenges.
Ion‑Exchange Chromatography – purification based on charge interactions;… #
Common downstream step for recombinant proteins. Example: polishing step for viral vectors. Buffer selection and column fouling affect performance.
KLa (Mass Transfer Coefficient) – parameter describing gas transfer rate;… #
Determines ability to meet cellular oxygen demand. Example: kLa of 0.1 h⁻¹ achieved with 0.8 vvm sparging. Accurate measurement requires dynamic gassing experiments.
Light‑Emitting Diode (LED) Bioreactor – system using LEDs for photobiorea… #
Enables precise wavelength selection for photosynthetic microorganisms. Example: cyanobacteria cultivation with red and blue LEDs. Heat management and uniform illumination are design considerations.
Liquid‑Phase Residence Time – average time a fluid element stays in the r… #
Influences product formation kinetics. Example: 24‑hour residence time in a continuous perfusion run. Non‑ideal flow patterns may cause deviation from design.
Microbial Strain Engineering – genetic modification to enhance production… #
Enables higher yields and reduced by‑products. Example: deletion of lactate dehydrogenase in E. coli to lower lactate formation. Regulatory compliance and stability are key concerns.
Monod Kinetics – model describing microbial growth as function of substra… #
Provides basis for feed control in fed‑batch. Example: μ = μmax S/(Ks+S). Parameter estimation requires careful experimentation.
MPa (Megapascal) Rating – pressure capability of bioreactor vessel; relat… #
Determines allowable operating pressure. Example: vessel rated at 0.3 MPa for aerobic fermentations. Exceeding rating can lead to mechanical failure.
Nanoparticle‑Based Sensors – optical or electrochemical probes using nano… #
Offer high sensitivity for metabolites. Example: gold‑nanoparticle sensor for lactate detection. Integration and long‑term stability remain challenges.
Oxygen Uptake Rate (OUR) – measure of oxygen consumption per volume; rela… #
Guides aeration strategy. Example: OUR of 150 mmol O₂ L⁻¹ h⁻¹ in high‑density CHO perfusion. Real‑time OUR estimation requires accurate DO and biomass data.
Off‑Gas Analyzer – instrument measuring CO₂ and O₂ in exhaust gas; relate… #
Provides indirect assessment of metabolic activity. Example: CO₂ evolution rate used to calculate substrate utilization. Calibration and gas lag time affect accuracy.
Optical Density (OD) – spectrophotometric measurement of cell turbidity;… #
Quick estimate of cell concentration in microbial cultures. Example: OD₆₀₀ = 0.5 corresponds to ~5 × 10⁸ cells/mL for E. coli. Linear range limits applicability at high densities.
Perfusion Bioreactor – continuous cell retention system with constant med… #
Allows extremely high cell densities (>10⁸ cells/mL). Example: ATF (Alternating Tangential Flow) perfusion for monoclonal antibodies. Membrane fouling and shear management are primary challenges.
Process Analytical Technology (PAT) – framework for real‑time quality mon… #
Enhances understanding of critical process parameters. Example: Raman spectroscopy for real‑time metabolite profiling. Implementation requires validated models and regulatory acceptance.
Process Development – systematic design of upstream and downstream steps;… #
Aims to achieve reproducible, cost‑effective production. Example: moving from 2‑L pilot to 2,000‑L commercial scale. Integration of data analytics improves robustness.
Process Scale‑Out – parallel operation of multiple reactors to increase c… #
Facilitates flexible manufacturing. Example: four 250‑L reactors running concurrently for vaccine production. Synchronization and consistent control across units are critical.
Pyrosequencing – DNA sequencing method used for strain verification; rela… #
Confirms genetic modifications. Example: verifying CRISPR edits in production strain. Requires bioinformatic support and quality control.
Recirculation Loop – system returning culture broth through a device; rel… #
Improves temperature uniformity and gas transfer. Example: external heat exchanger in a large‑scale stirred‑tank. Loop contamination and pressure drop must be monitored.
Residence Time Distribution (RTD) – characterization of flow behavior; re… #
Provides insight into mixing and dead‑zones. Example: pulse‑input tracer test revealing non‑ideal flow in a 500‑L reactor. Data informs design modifications.
Reverse Osmosis (RO) Filtration – membrane process for water purification… #
Supplies high‑quality water for media preparation. Example: 0.2 µm RO system delivering < 0.1 ppm total organic carbon. Membrane fouling and maintenance affect reliability.
Scale‑Down Model – laboratory representation of large‑scale heterogeneiti… #
Used to test strain robustness. Example: intermittent pH shifts mimicking large‑scale gradients. Provides data for process control strategy refinement.
Single‑Use Bioreactor – disposable vessel with integrated sensors; relate… #
Reduces cleaning validation effort. Example: 200‑L single‑use stirred‑tank for rapid clinical batch. Limited by bag material strength and extractable leachables.
Specific Growth Rate (μ) – rate of cell mass increase per unit biomass; r… #
Central to kinetic modeling. Example: μ = 0.03 h⁻¹ in a fed‑batch CHO culture. Determined from online cell density data.
Specific Productivity (qP) – amount of product formed per cell per time;… #
Target metric for process optimization. Example: qP = 30 pg cell⁻¹ day⁻¹ for monoclonal antibody. Balancing qP and cell health is a key trade‑off.
Sparger Design – configuration influencing bubble size and distribution;… #
Determines kLa and shear. Example: 2 mm pore‑size sparger achieving fine bubbles for high oxygen transfer. Clogging by media components can reduce efficiency.
Stirred‑Tank Reactor (STR) – most common bioreactor type with an impeller… #
Offers flexible control of temperature, pH, and DO. Example: 10‑L stainless‑steel STR for recombinant protein production. Scale‑up challenges include power input and shear.
Substrate Inhibition – reduction of growth rate at high substrate concent… #
Must be avoided in fed‑batch designs. Example: excessive glucose leading to lactate accumulation in CHO cultures. Controlled feeding mitigates inhibition.
Supercritical CO₂ Extraction – technique for product recovery using super… #
Enables solvent‑free extraction of hydrophobic compounds. Example: extracting terpenes from engineered yeast. Equipment cost and pressure safety are considerations.
Thermodynamic Limit – maximum achievable conversion based on energy consi… #
Guides realistic yield expectations. Example: theoretical ethanol yield from glucose is 0.511 g g⁻¹. Process design must account for kinetic constraints.
Trace Element Supplement – micronutrients required for enzyme cofactors;… #
Includes zinc, copper, manganese. Example: adding 0.1 mg L⁻¹ zinc to improve recombinant protein folding. Over‑supplementation can cause precipitation.
Ultra‑High‑Performance Liquid Chromatography (UHPLC) – analytical techniq… #
Provides high resolution and speed. Example: monitoring monoclonal antibody charge variants. Requires careful method development and column maintenance.
Vacuum Degassing – removal of dissolved gases using reduced pressure; rel… #
Reduces bubble formation in downstream filtration. Example: degassing media before sterile filtration. Over‑degassing may lead to temperature drop.
Variable Volume Bioreactor – system where working volume changes during o… #
Allows addition of feed without overflow. Example: volume increase from 2 L to 5 L during fed‑batch. Requires flexible sensor calibration.
Viscosity Measurement – determination of fluid resistance to flow; relate… #
Influences power requirement and mixing efficiency. Example: high‑viscosity broth in filamentous fungi requiring low‑speed agitation. In‑line viscometers provide real‑time data.
Viral Vector Production – bioreactor process for gene therapy vectors; re… #
Requires strict biosafety and high purity. Example: HEK293 suspension culture in 10‑L STR producing adeno‑associated virus at 1 × 10¹³ vg L⁻¹. Scale‑up faces challenges in vector stability and downstream removal of host DNA.
Volumetric Productivity – amount of product generated per reactor volume… #
Key performance indicator for process economics. Example: 10 g L⁻¹ day⁻¹ for recombinant enzyme in fed‑batch. Optimization involves balancing feed rate, oxygen supply, and cell density.
Yield Coefficient (Y) – ratio of product formed to substrate consumed; re… #
Guides feed strategy and economic analysis. Example: YP/S = 0.5 g product g⁻¹ substrate for a bacterial fermentation. Accurate measurement requires precise substrate and product quantification.
Zero‑Order Kinetics – reaction rate independent of substrate concentratio… #
Occurs when enzymes are saturated. Example: constant product formation after substrate depletion in stationary phase. Modeling must incorporate transition to zero‑order behavior.