1
|
Winter M, Achleitner L, Satzer P. Soft sensor for viable cell counting by measuring dynamic oxygen uptake rate. N Biotechnol 2024; 83:16-25. [PMID: 38878999 DOI: 10.1016/j.nbt.2024.06.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 05/27/2024] [Accepted: 06/08/2024] [Indexed: 06/20/2024]
Abstract
Regulatory authorities in biopharmaceutical industry emphasize process design by process understanding but applicable tools that are easy to implement are still missing. Soft sensors are a promising tool for the implementation of the Quality by Design (QbD) approach and Process Analytical Technology (PAT). In particular, the correlation between viable cell counting and oxygen consumption was investigated, but problems remained: Either the process had to be modified for excluding CO2 in pH control, or complex kLa models had to be set up for specific processes. In this work, a non-invasive soft sensor for simplified on-line cell counting based on dynamic oxygen uptake rate was developed with no need of special equipment. The dynamic oxygen uptake rates were determined by automated and periodic interruptions of gas supply in DASGIP® bioreactor systems, realized by a programmed Visual Basic script in the DASware® control software. With off-line cell counting, the two parameters were correlated based on linear regression and led to a robust model with a correlation coefficient of 0.92. Avoidance of oxygen starvation was achieved by gas flow reactivation at a certain minimum dissolved oxygen concentration. The soft sensor model was established in the exponential growth phase of a Chinese Hamster Ovary fed-batch process. Control studies showed no impact on cell growth by the discontinuous gas supply. This soft sensor is the first to be presented that does not require any specialized additional equipment as the methodology relies solely on the direct measurement of oxygen consumed by the cells in the bioreactor.
Collapse
Affiliation(s)
- M Winter
- Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria
| | - L Achleitner
- Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria; Austrian Centre of Industrial Biotechnology, Muthgasse 11, 1190 Wien, Austria
| | - P Satzer
- Department of Biotechnology, University of Natural Resources and Life Sciences, Vienna, Austria.
| |
Collapse
|
2
|
Shohan S, Zeng Y, Chen X, Jin R, Shirwaiker R. Investigating dielectric spectroscopy and soft sensing for nondestructive quality assessment of engineered tissues. Biosens Bioelectron 2022; 216:114286. [DOI: 10.1016/j.bios.2022.114286] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Revised: 03/29/2022] [Accepted: 04/11/2022] [Indexed: 11/02/2022]
|
3
|
Floris P, Dorival-García N, Lewis G, Josland G, Merriman D, Bones J. Real-time characterization of mammalian cell culture bioprocesses by magnetic sector MS. ANALYTICAL METHODS : ADVANCING METHODS AND APPLICATIONS 2020; 12:5601-5612. [PMID: 33179638 DOI: 10.1039/d0ay01563f] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Mammalian cell culture processes were characterized upon the analysis of the exhaust-gas composition achieved through the on-line integration of a magnetic sector MS analyser with benchtop bioreactors. The non-invasive configuration of the magnetic sector MS provided continuous evaluation of the bioreactor's exhaust gas filter integrity and facilitated the accurate quantification of O2 and CO2 levels in the off-gas stream which ensured preserved bioreactor sterility prior to cell inoculation and provided evidence of the ongoing cellular respiratory activity throughout the cultures. Real-time determination of process parameters such as the Respiratory Quotient (RQ) allowed for precise pin-pointing of the occurrence of shifts in cellular metabolism which were correlated to depletion of key nutrients in the growth medium, demonstrating the suitability of this technology for tracking cell culture process performance.
Collapse
Affiliation(s)
- Patrick Floris
- Characterisation and Comparability Laboratory, NIBRT-The National Institute for Bioprocessing Research and Training, Fosters avenue, Mount Merrion, Blackrock, Co. Dublin A94 X099, Ireland.
| | - Noemí Dorival-García
- Characterisation and Comparability Laboratory, NIBRT-The National Institute for Bioprocessing Research and Training, Fosters avenue, Mount Merrion, Blackrock, Co. Dublin A94 X099, Ireland.
| | - Graham Lewis
- Thermo Fisher Scientific, Ion Path, Road Three, Winsford, CW7 3GA, UK
| | - Graham Josland
- Thermo Fisher Scientific, Ion Path, Road Three, Winsford, CW7 3GA, UK
| | - Daniel Merriman
- Thermo Fisher Scientific, Ion Path, Road Three, Winsford, CW7 3GA, UK
| | - Jonathan Bones
- Characterisation and Comparability Laboratory, NIBRT-The National Institute for Bioprocessing Research and Training, Fosters avenue, Mount Merrion, Blackrock, Co. Dublin A94 X099, Ireland. and School of Chemical and Bioprocess Engineering, University College Dublin, Dublin 4, Belfield, D04 V1W8, Ireland
| |
Collapse
|
4
|
Novel Carbon Dioxide-Based Method for Accurate Determination of pH and pCO2 in Mammalian Cell Culture Processes. Processes (Basel) 2020. [DOI: 10.3390/pr8050520] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
In mammalian cell culture, especially in pharmaceutical manufacturing, pH is a critical process parameter that has to be controlled as accurately as possible. Not only does pH directly affect cell culture performance, ensuring a comparable pH is also crucial for scaling and transfer of processes. A sample-based offline pH measurement is commonly used to ensure correct bioreactor pH probe signals after sterilization and as a detection measure for drifts of probe signals. However, the sample-based pH offline measurement does not necessarily deliver required accuracy. Offsets between bioreactor pH and sample pH heavily depend on equipment, local procedures and the offline measurement method that is used. This article adequately describes a novel, non-invasive method to determine pH and pCO2 in sterile bioreactors without the need to sample and measure offline. This method utilizes the chemical correlation between carbon dioxide in the gas phase, dissolved carbon dioxide, bicarbonate and dependent proton concentrations that directly affect the pH in carbonate buffered systems. The proposed carbon dioxide-based pH reference method thereby is able to accurately determine the true pH in the bioreactor without the need to sample. The proposed method is independent of scale and bioreactor configuration and does not depend on local procedures that may differ between sites, scales or operators. Applicability of the method for both stainless steel and single use bioreactors is shown. Furthermore, the very same principles are applicable for non-invasive, online pCO2 monitoring.
Collapse
|
5
|
Chopda VR, Holzberg T, Ge X, Folio B, Tolosa M, Kostov Y, Tolosa L, Rao G. Real-time dissolved carbon dioxide monitoring I: Application of a novel in situ sensor for CO 2 monitoring and control. Biotechnol Bioeng 2020; 117:981-991. [PMID: 31840812 PMCID: PMC7079146 DOI: 10.1002/bit.27253] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2019] [Revised: 12/10/2019] [Accepted: 12/13/2019] [Indexed: 12/21/2022]
Abstract
Dissolved carbon dioxide (dCO2 ) is a well-known critical parameter in bioprocesses due to its significant impact on cell metabolism and on product quality attributes. Processes run at small-scale faces many challenges due to limited options for modular sensors for online monitoring and control. Traditional sensors are bulky, costly, and invasive in nature and do not fit in small-scale systems. In this study, we present the implementation of a novel, rate-based technique for real-time monitoring of dCO2 in bioprocesses. A silicone sampling probe that allows the diffusion of CO2 through its wall was inserted inside a shake flask/bioreactor and then flushed with air to remove the CO2 that had diffused into the probe from the culture broth (sensor was calibrated using air as zero-point calibration). The gas inside the probe was then allowed to recirculate through gas-impermeable tubing to a CO2 monitor. We have shown that by measuring the initial diffusion rate of CO2 into the sampling probe we were able to determine the partial pressure of the dCO2 in the culture. This technique can be readily automated, and measurements can be made in minutes. Demonstration experiments conducted with baker's yeast and Yarrowia lipolytica yeast cells in both shake flasks and mini bioreactors showed that it can monitor dCO2 in real-time. Using the proposed sensor, we successfully implemented a dCO2 -based control scheme, which resulted in significant improvement in process performance.
Collapse
Affiliation(s)
- Viki R. Chopda
- Department of Chemical, Biochemical and Environmental Engineering, Center for Advanced Sensor TechnologyUniversity of MarylandBaltimoreMaryland
| | - Timothy Holzberg
- Department of Chemical, Biochemical and Environmental Engineering, Center for Advanced Sensor TechnologyUniversity of MarylandBaltimoreMaryland
| | - Xudong Ge
- Department of Chemical, Biochemical and Environmental Engineering, Center for Advanced Sensor TechnologyUniversity of MarylandBaltimoreMaryland
| | - Brandon Folio
- Department of Chemical, Biochemical and Environmental Engineering, Center for Advanced Sensor TechnologyUniversity of MarylandBaltimoreMaryland
| | - Michael Tolosa
- Department of Chemical, Biochemical and Environmental Engineering, Center for Advanced Sensor TechnologyUniversity of MarylandBaltimoreMaryland
| | - Yordan Kostov
- Department of Chemical, Biochemical and Environmental Engineering, Center for Advanced Sensor TechnologyUniversity of MarylandBaltimoreMaryland
| | - Leah Tolosa
- Department of Chemical, Biochemical and Environmental Engineering, Center for Advanced Sensor TechnologyUniversity of MarylandBaltimoreMaryland
| | - Govind Rao
- Department of Chemical, Biochemical and Environmental Engineering, Center for Advanced Sensor TechnologyUniversity of MarylandBaltimoreMaryland
| |
Collapse
|
6
|
Goh HY, Sulu M, Alosert H, Lewis GL, Josland GD, Merriman DE. Applications of off-gas mass spectrometry in fed-batch mammalian cell culture. Bioprocess Biosyst Eng 2019; 43:483-493. [PMID: 31709471 PMCID: PMC7007916 DOI: 10.1007/s00449-019-02242-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Accepted: 10/28/2019] [Indexed: 11/30/2022]
Abstract
Off-gas analysis using a magnetic sector mass spectrometer was performed in mammalian cell cultures in the fed-batch mode at the 5 L bench and 50 L pilot scales. Factors affecting the MS gas traces were identified during the duration of the fed-batch cultures. Correlation between viable cell concentration (VCC) and oxygen concentration of the inlet gas into the bioreactor (O2-in) resulted in R2 ≈ 0.9; O2-in could be used as a proxy for VCC. Oxygen mass transfer (kLa) was also quantified throughout the culture period with antifoam addition at different time points which is shown to lower the kLa. Real-time specific oxygen consumption rate (qO2) of 2–20 pmol/cell/day throughout the bioreactor runs were within the range of values reported in literature for mammalian cell cultures. We also report, to our knowledge, the first instance of a distinct correlation between respiration quotient (RQ) and the metabolic state of the cell culture with regard to lactate production phase (average RQ > 1) and consumption phase (average RQ < 1).
Collapse
Affiliation(s)
- Hai-Yuan Goh
- The Advanced Centre for Biochemical Engineering, Department of Biochemical Engineering, University College London, Bernard Katz Building, Gordon Street, London, WC1H 0AH, UK
| | - Michael Sulu
- The Advanced Centre for Biochemical Engineering, Department of Biochemical Engineering, University College London, Bernard Katz Building, Gordon Street, London, WC1H 0AH, UK.
| | - Haneen Alosert
- The Advanced Centre for Biochemical Engineering, Department of Biochemical Engineering, University College London, Bernard Katz Building, Gordon Street, London, WC1H 0AH, UK
| | - Graham L Lewis
- Thermo Fisher Scientific, Ion Path, Road 3, Winsford, CW7 3GA, Cheshire, UK
| | - Graham D Josland
- Thermo Fisher Scientific, Ion Path, Road 3, Winsford, CW7 3GA, Cheshire, UK
| | - Daniel E Merriman
- Thermo Fisher Scientific, Ion Path, Road 3, Winsford, CW7 3GA, Cheshire, UK
| |
Collapse
|
7
|
Kroll P, Hofer A, Ulonska S, Kager J, Herwig C. Model-Based Methods in the Biopharmaceutical Process Lifecycle. Pharm Res 2017; 34:2596-2613. [PMID: 29168076 PMCID: PMC5736780 DOI: 10.1007/s11095-017-2308-y] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2017] [Accepted: 09/21/2017] [Indexed: 12/18/2022]
Abstract
Model-based methods are increasingly used in all areas of biopharmaceutical process technology. They can be applied in the field of experimental design, process characterization, process design, monitoring and control. Benefits of these methods are lower experimental effort, process transparency, clear rationality behind decisions and increased process robustness. The possibility of applying methods adopted from different scientific domains accelerates this trend further. In addition, model-based methods can help to implement regulatory requirements as suggested by recent Quality by Design and validation initiatives. The aim of this review is to give an overview of the state of the art of model-based methods, their applications, further challenges and possible solutions in the biopharmaceutical process life cycle. Today, despite these advantages, the potential of model-based methods is still not fully exhausted in bioprocess technology. This is due to a lack of (i) acceptance of the users, (ii) user-friendly tools provided by existing methods, (iii) implementation in existing process control systems and (iv) clear workflows to set up specific process models. We propose that model-based methods be applied throughout the lifecycle of a biopharmaceutical process, starting with the set-up of a process model, which is used for monitoring and control of process parameters, and ending with continuous and iterative process improvement via data mining techniques.
Collapse
Affiliation(s)
- Paul Kroll
- Research Area Biochemical Engineering, Institute of Chemical Environmental and Biological Engineering, Vienna University of Technology, Gumpendorfer Straße 1a - 166/4, A-1060, Vienna, Austria
- Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, TU Wien, Vienna, Austria
| | - Alexandra Hofer
- Research Area Biochemical Engineering, Institute of Chemical Environmental and Biological Engineering, Vienna University of Technology, Gumpendorfer Straße 1a - 166/4, A-1060, Vienna, Austria
| | - Sophia Ulonska
- Research Area Biochemical Engineering, Institute of Chemical Environmental and Biological Engineering, Vienna University of Technology, Gumpendorfer Straße 1a - 166/4, A-1060, Vienna, Austria
| | - Julian Kager
- Research Area Biochemical Engineering, Institute of Chemical Environmental and Biological Engineering, Vienna University of Technology, Gumpendorfer Straße 1a - 166/4, A-1060, Vienna, Austria
| | - Christoph Herwig
- Research Area Biochemical Engineering, Institute of Chemical Environmental and Biological Engineering, Vienna University of Technology, Gumpendorfer Straße 1a - 166/4, A-1060, Vienna, Austria.
- Christian Doppler Laboratory for Mechanistic and Physiological Methods for Improved Bioprocesses, TU Wien, Vienna, Austria.
| |
Collapse
|
8
|
Lirtsman V, Golosovsky M, Davidov D. Surface plasmon excitation using a Fourier-transform infrared spectrometer: Live cell and bacteria sensing. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2017; 88:103105. [PMID: 29092505 DOI: 10.1063/1.4997388] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report an accessory for beam collimation to be used as a plug-in for a conventional Fourier-Transform Infrared (FTIR) spectrometer. The beam collimator makes use of the built-in focusing mirror of the FTIR spectrometer which focuses the infrared beam onto the pinhole mounted in the place usually reserved for the sample. The beam is collimated by a small parabolic mirror and is redirected to the sample by a pair of plane mirrors. The reflected beam is conveyed by another pair of plane mirrors to the built-in detector of the FTIR spectrometer. This accessory is most useful for the surface plasmon excitation. We demonstrate how it can be employed for label-free and real-time sensing of dynamic processes in bacterial and live cell layers. In particular, by measuring the intensity of the CO2 absorption peak one can assess the cell layer metabolism, while by measuring the position of the surface plasmon resonance one assesses the cell layer morphology.
Collapse
Affiliation(s)
- Vladislav Lirtsman
- The Racah Institute of Physics, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Michael Golosovsky
- The Racah Institute of Physics, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| | - Dan Davidov
- The Racah Institute of Physics, The Hebrew University of Jerusalem, 91904 Jerusalem, Israel
| |
Collapse
|
9
|
Brunner M, Braun P, Doppler P, Posch C, Behrens D, Herwig C, Fricke J. The impact of pH inhomogeneities on CHO cell physiology and fed-batch process performance - two-compartment scale-down modelling and intracellular pH excursion. Biotechnol J 2017; 12. [DOI: 10.1002/biot.201600633] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2016] [Revised: 12/17/2016] [Accepted: 01/10/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Matthias Brunner
- Research Division Biochemical Engineering; Institute of Chemical Engineering; Vienna University of Technology; Vienna Austria
- CD Laboratory on Mechanistic and Physiological Methods for Improved Bioprocesses; Vienna University of Technology; Vienna Austria
| | - Philipp Braun
- Research Division Biochemical Engineering; Institute of Chemical Engineering; Vienna University of Technology; Vienna Austria
- CD Laboratory on Mechanistic and Physiological Methods for Improved Bioprocesses; Vienna University of Technology; Vienna Austria
| | - Philipp Doppler
- Research Division Biochemical Engineering; Institute of Chemical Engineering; Vienna University of Technology; Vienna Austria
- CD Laboratory on Mechanistic and Physiological Methods for Improved Bioprocesses; Vienna University of Technology; Vienna Austria
| | | | | | - Christoph Herwig
- Research Division Biochemical Engineering; Institute of Chemical Engineering; Vienna University of Technology; Vienna Austria
- CD Laboratory on Mechanistic and Physiological Methods for Improved Bioprocesses; Vienna University of Technology; Vienna Austria
| | - Jens Fricke
- Research Division Biochemical Engineering; Institute of Chemical Engineering; Vienna University of Technology; Vienna Austria
- CD Laboratory on Mechanistic and Physiological Methods for Improved Bioprocesses; Vienna University of Technology; Vienna Austria
| |
Collapse
|
10
|
Investigation of the interactions of critical scale-up parameters (pH, pO 2 and pCO 2) on CHO batch performance and critical quality attributes. Bioprocess Biosyst Eng 2016; 40:251-263. [PMID: 27752770 PMCID: PMC5274649 DOI: 10.1007/s00449-016-1693-7] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 10/07/2016] [Indexed: 12/20/2022]
Abstract
Understanding process parameter interactions and their effects on mammalian cell cultivations is an essential requirement for robust process scale-up. Furthermore, knowledge of the relationship between the process parameters and the product critical quality attributes (CQAs) is necessary to satisfy quality by design guidelines. So far, mainly the effect of single parameters on CQAs was investigated. Here, we present a comprehensive study to investigate the interactions of scale-up relevant parameters as pH, pO2 and pCO2 on CHO cell physiology, process performance and CQAs, which was based on design of experiments and extended product quality analytics. The study used a novel control strategy in which process parameters were decoupled from each other, and thus allowed their individual control at defined set points. Besides having identified the impact of single parameters on process performance and product quality, further significant interaction effects of process parameters on specific cell growth, specific productivity and amino acid metabolism could be derived using this method. Concerning single parameter effects, several monoclonal antibody (mAb) charge variants were affected by process pCO2 and pH. N-glycosylation analysis showed positive correlations between mAb sialylation and high pH values as well as a relationship between high mannose variants and process pH. This study additionally revealed several interaction effects as process pH and pCO2 interactions on mAb charge variants and N-glycosylation pattern. Hence, through our process control strategy and multivariate investigation, novel significant process parameter interactions and single effects were identified which have to be taken into account especially for process scale-up.
Collapse
|
11
|
Fernandes de Sousa S, Bastin G, Jolicoeur M, Vande Wouwer A. Dynamic metabolic flux analysis using a convex analysis approach: Application to hybridoma cell cultures in perfusion. Biotechnol Bioeng 2015; 113:1102-12. [DOI: 10.1002/bit.25879] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2015] [Revised: 10/30/2015] [Accepted: 11/01/2015] [Indexed: 12/22/2022]
Affiliation(s)
| | - Georges Bastin
- Department of Mathematical Engineering; ICTEAM; Catholic University of Louvain; Louvain-La-Neuve Belgium
| | - Mario Jolicoeur
- Department of Chemical Engineering; Laboratory in Applied Metabolic Engineering; Polytechnic University of Montreal; Montréal Canada
| | | |
Collapse
|
12
|
Biechele P, Busse C, Solle D, Scheper T, Reardon K. Sensor systems for bioprocess monitoring. Eng Life Sci 2015. [DOI: 10.1002/elsc.201500014] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- Philipp Biechele
- Institute of Technical Chemistry; Leibniz University; Hannover Germany
| | - Christoph Busse
- Institute of Technical Chemistry; Leibniz University; Hannover Germany
| | - Dörte Solle
- Institute of Technical Chemistry; Leibniz University; Hannover Germany
| | - Thomas Scheper
- Institute of Technical Chemistry; Leibniz University; Hannover Germany
| | - Kenneth Reardon
- Department of Chemical and Biological Engineering; Colorado State University; Fort Collins CO USA
| |
Collapse
|
13
|
Ex situonline monitoring: application, challenges and opportunities for biopharmaceuticals processes. ACTA ACUST UNITED AC 2014. [DOI: 10.4155/pbp.14.22] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
14
|
Popović MK, Senz M, Bader J, Skelac L, Schilf W, Bajpai R. Positive effect of reduced aeration rate on secretion of alpha-amylase and neutral proteases during pressurised fermentation of thermophilic Bacillus caldolyticus. N Biotechnol 2014; 31:141-9. [PMID: 24239980 DOI: 10.1016/j.nbt.2013.10.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2013] [Revised: 10/08/2013] [Accepted: 10/25/2013] [Indexed: 01/26/2023]
Abstract
The thermophilic microorganism Bacillus caldolyticus was incubated in laboratory scale stirred bioreactors under pressurised conditions at different aeration rates. Increased amounts of CO2/bicarbonate were solubilised under the chosen conditions. A reduction in aeration rate from 1 vvm to 0.1 vvm resulted in accumulation of CO2 and bicarbonate up to 126 mg l(-1) and 733 mg l(-1), respectively and also increased secretion of α-amylase and neutral proteases (increases of 123% and 52%, respectively). In this paper, the effect of reduced aeration rate on CO2/bicarbonate concentration and enzyme activities is presented. The selected fermentation conditions are closely related to those prevalent in large scale bioreactors and may offer the possibility of achieving high enzyme yields at reduced aeration costs on an industrial scale.
Collapse
Affiliation(s)
- M K Popović
- Institute of Biotechnology, Beuth University of Applied Sciences, Seestraße 64, 13347 Berlin, Germany.
| | - M Senz
- Institute of Biotechnology, University of Technology, Seestraße 13, 13353 Berlin, Germany
| | - J Bader
- Institute of Biotechnology, Beuth University of Applied Sciences, Seestraße 64, 13347 Berlin, Germany
| | - L Skelac
- Research Institute of Brewing, Seestraße 13, 13353 Berlin, Germany
| | - W Schilf
- Institute of Biotechnology, Beuth University of Applied Sciences, Seestraße 64, 13347 Berlin, Germany
| | - R Bajpai
- Chemical Engineering Department, University of Louisiana at Lafayette, Lafayette, LA 70508, USA
| |
Collapse
|
15
|
Ma Y, Yung LYL. Detection of Dissolved CO2 Based on the Aggregation of Gold Nanoparticles. Anal Chem 2014; 86:2429-35. [DOI: 10.1021/ac403256s] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Ying Ma
- Department of Chemical and
Biomolecular Engineering, National University of Singapore, 10 Kent
Ridge Crescent, Singapore 119260, Singapore
| | - Lin-Yue Lanry Yung
- Department of Chemical and
Biomolecular Engineering, National University of Singapore, 10 Kent
Ridge Crescent, Singapore 119260, Singapore
| |
Collapse
|
16
|
Goudar CT, Biener RK, Piret JM, Konstantinov KB. Metabolic flux estimation in mammalian cell cultures. Methods Mol Biol 2014; 1104:193-209. [PMID: 24297417 DOI: 10.1007/978-1-62703-733-4_13] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Metabolic flux analysis with its ability to quantify cellular metabolism is an attractive tool for accelerating cell line selection, medium optimization, and other bioprocess development activities. In the stoichiometric flux estimation approach, unknown fluxes are determined using intracellular metabolite mass balance expressions and measured extracellular rates. The simplicity of the stoichiometric approach extends its application to most cell culture systems, and the steps involved in metabolic flux estimation by the stoichiometric method are presented in detail in this chapter. Specifically, overdetermined systems are analyzed since the extra measurements can be used to check for gross measurement errors and system consistency. Cell-specific rates comprise the input data for flux estimation, and the logistic modeling approach is described for robust-specific rate estimation in batch and fed-batch systems. A simplified network of mammalian cell metabolism is used to illustrate the flux estimation procedure, and the steps leading up the consistency index determination are presented. If gross measurement errors are detected, a technique for determining the source of gross measurement error is also described. A computer program that performs most of the calculation described in this chapter is presented, and references to flux estimation software are provided. The procedure presented in this chapter should enable rapid metabolic flux estimation in any mammalian cell bioreaction network by the stoichiometric approach.
Collapse
|
17
|
Abstract
Lab-scale stirred-tank bioreactors (0.2-20 l) are used for fundamental research on animal cells and in process development and troubleshooting for large-scale production. In this chapter, different configurations of bioreactor systems are shortly discussed and setting up these different configurations is described. In addition, online measurement and control of bioreactor parameters is described, with special attention to controller settings (PID) and online measurement of oxygen consumption and carbon dioxide production. Finally, methods for determining the oxygen transfer coefficient are described.
Collapse
Affiliation(s)
- Dirk E Martens
- Bioprocess Engineering, Wageningen University, Wageningen, The Netherlands,
| | | | | |
Collapse
|
18
|
Winckler S, Krueger R, Schnitzler T, Zang W, Fischer R, Biselli M. A sensitive monitoring system for mammalian cell cultivation processes: a PAT approach. Bioprocess Biosyst Eng 2013; 37:901-12. [DOI: 10.1007/s00449-013-1062-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Accepted: 09/09/2013] [Indexed: 11/30/2022]
|
19
|
Holland T, Blessing D, Hellwig S, Sack M. The in-line measurement of plant cell biomass using radio frequency impedance spectroscopy as a component of process analytical technology. Biotechnol J 2013; 8:1231-40. [PMID: 24039008 DOI: 10.1002/biot.201300125] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Revised: 06/05/2013] [Accepted: 07/18/2013] [Indexed: 01/20/2023]
Abstract
Radio frequency impedance spectroscopy (RFIS) is a robust method for the determination of cell biomass during fermentation. RFIS allows non-invasive in-line monitoring of the passive electrical properties of cells in suspension and can distinguish between living and dead cells based on their distinct behavior in an applied radio frequency field. We used continuous in situ RFIS to monitor batch-cultivated plant suspension cell cultures in stirred-tank bioreactors and compared the in-line data to conventional off-line measurements. RFIS-based analysis was more rapid and more accurate than conventional biomass determination, and was sensitive to changes in cell viability. The higher resolution of the in-line measurement revealed subtle changes in cell growth which were not accessible using conventional methods. Thus, RFIS is well suited for correlating such changes with intracellular states and product accumulation, providing unique opportunities for employing systems biotechnology and process analytical technology approaches to increase product yield and quality.
Collapse
Affiliation(s)
- Tanja Holland
- Fraunhofer Institute for Molecular Biology and Applied Ecology, Aachen, Germany.
| | | | | | | |
Collapse
|
20
|
Niu H, Daukandt M, Rodriguez C, Fickers P, Bogaerts P. Dynamic modeling of methylotrophic Pichia pastoris culture with exhaust gas analysis: From cellular metabolism to process simulation. Chem Eng Sci 2013. [DOI: 10.1016/j.ces.2012.11.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
|
21
|
Dissolved carbon dioxide concentration profiles during very-high-gravity ethanol fermentation. Biochem Eng J 2012. [DOI: 10.1016/j.bej.2012.07.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
22
|
Aehle M, Kuprijanov A, Schaepe S, Simutis R, Lübbert A. Simplified off-gas analyses in animal cell cultures for process monitoring and control purposes. Biotechnol Lett 2011; 33:2103-10. [DOI: 10.1007/s10529-011-0686-5] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Accepted: 06/22/2011] [Indexed: 10/18/2022]
|
23
|
Berrios J, Altamirano C, Osses N, Gonzalez R. Continuous CHO cell cultures with improved recombinant protein productivity by using mannose as carbon source: Metabolic analysis and scale-up simulation. Chem Eng Sci 2011. [DOI: 10.1016/j.ces.2011.03.011] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
24
|
Goudar CT, Piret JM, Konstantinov KB. Estimating cell specific oxygen uptake and carbon dioxide production rates for mammalian cells in perfusion culture. Biotechnol Prog 2011; 27:1347-57. [DOI: 10.1002/btpr.646] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Revised: 04/01/2011] [Indexed: 11/08/2022]
|
25
|
Kowollik S, Schnitzler T, Biselli M, Krueger R, Zang W, Peuscher A, Schillberg S, Fischer R. Die Rolle des Respirationsquotienten in der Zellkulturfermentation. CHEM-ING-TECH 2010. [DOI: 10.1002/cite.201050393] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
26
|
Xing Z, Kenty BM, Li ZJ, Lee SS. Scale-up analysis for a CHO cell culture process in large-scale bioreactors. Biotechnol Bioeng 2009; 103:733-46. [PMID: 19280669 DOI: 10.1002/bit.22287] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Bioprocess scale-up is a fundamental component of process development in the biotechnology industry. When scaling up a mammalian cell culture process, it is important to consider factors such as mixing time, oxygen transfer, and carbon dioxide removal. In this study, cell-free mixing studies were performed in production scale 5,000-L bioreactors to evaluate scale-up issues. Using the current bioreactor configuration, the 5,000-L bioreactor had a lower oxygen transfer coefficient, longer mixing time, and lower carbon dioxide removal rate than that was observed in bench scale 5- and 20-L bioreactors. The oxygen transfer threshold analysis indicates that the current 5,000-L configuration can only support a maximum viable cell density of 7 x 10(6) cells mL(-1). Moreover, experiments using a dual probe technique demonstrated that pH and dissolved oxygen gradients may exist in 5,000-L bioreactors using the current configuration. Empirical equations were developed to predict mixing time, oxygen transfer coefficient, and carbon dioxide removal rate under different mixing-related engineering parameters in the 5,000-L bioreactors. These equations indicate that increasing bottom air sparging rate is more efficient than increasing power input in improving oxygen transfer and carbon dioxide removal. Furthermore, as the liquid volume increases in a production bioreactor operated in fed-batch mode, bulk mixing becomes a challenge. The mixing studies suggest that the engineering parameters related to bulk mixing and carbon dioxide removal in the 5,000-L bioreactors may need optimizing to mitigate the risk of different performance upon process scale-up.
Collapse
Affiliation(s)
- Zizhuo Xing
- Process Sciences, Biologics Manufacturing and Process Development, Worldwide Medicines Group, Bristol-Myers Squibb Company, Syracuse, NY 13221-4755, USA
| | | | | | | |
Collapse
|
27
|
pH and base counterion affect succinate production in dual-phase Escherichia coli fermentations. J Ind Microbiol Biotechnol 2009; 36:1101-9. [PMID: 19484279 DOI: 10.1007/s10295-009-0594-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2009] [Accepted: 05/11/2009] [Indexed: 10/20/2022]
Abstract
Succinate production was studied in Escherichia coli AFP111, which contains mutations in pyruvate formate lyase (pfl), lactate dehydrogenase (ldhA) and the phosphotransferase system glucosephosphotransferase enzyme II (ptsG). Two-phase fermentations using a defined medium at several controlled levels of pH were conducted in which an aerobic cell growth phase was followed by an anaerobic succinate production phase using 100% (v/v) CO(2). A pH of 6.4 yielded the highest specific succinate productivity. A metabolic flux analysis at a pH of 6.4 using (13)C-labeled glucose showed that 61% of the PEP partitioned to oxaloacetate and 39% partitioned to pyruvate, while 93% of the succinate was formed via the reductive arm of the TCA cycle. The flux distribution at a pH of 6.8 was also analyzed and was not significantly different compared to that at a pH of 6.4. Ca(OH)(2) was superior to NaOH or KOH as the base for controlling the pH. By maintaining the pH at 6.4 using 25% (w/v) Ca(OH)(2), the process achieved an average succinate productivity of 1.42 g/l h with a yield of 0.61 g/g.
Collapse
|
28
|
Abstract
Biofilms are important in aquatic nutrient cycling and microbial proliferation. In these structures, nutrients like carbon are channeled into the production of extracellular polymeric substances or cell division; both are vital for microbial survival and propagation. The aim of this study was to assess carbon channeling into cellular or noncellular fractions in biofilms. Growing in tubular reactors, biofilms of our model strain Pseudomonas sp. strain CT07 produced cells to the planktonic phase from the early stages of biofilm development, reaching pseudo steady state with a consistent yield of approximately 10(7) cells.cm(-2).h(-1) within 72 h. Total direct counts and image analysis showed that most of the converted carbon occurred in the noncellular fraction, with the released and sessile cells accounting for <10% and <2% of inflowing carbon, respectively. A CO(2) evolution measurement system (CEMS) that monitored CO(2) in the gas phase was developed to perform a complete carbon balance across the biofilm. The measurement system was able to determine whole-biofilm CO(2) production rates in real time and showed that gaseous CO(2) production accounted for 25% of inflowing carbon. In addition, the CEMS made it possible to measure biofilm response to changing environmental conditions; changes in temperature or inflowing carbon concentration were followed by a rapid response in biofilm metabolism and the establishment of new steady-state conditions.
Collapse
|
29
|
Rodrigues ME, Costa AR, Henriques M, Azeredo J, Oliveira R. Technological progresses in monoclonal antibody production systems. Biotechnol Prog 2009; 26:332-51. [DOI: 10.1002/btpr.348] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
|
30
|
Yu P, Lee TS, Zeng Y, Low HT. A 3D analysis of oxygen transfer in a low-cost micro-bioreactor for animal cell suspension culture. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2007; 85:59-68. [PMID: 17064809 DOI: 10.1016/j.cmpb.2006.09.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2005] [Revised: 09/04/2006] [Accepted: 09/12/2006] [Indexed: 05/12/2023]
Abstract
A 3D numerical model was developed to study the flow field and oxygen transport in a micro-bioreactor with a rotating magnetic bar on the bottom to mix the culture medium. The Reynolds number (Re) was kept in the range of 100-716 to ensure laminar environment for animal cell culture. The volumetric oxygen transfer coefficient (k(L)a) was determined from the oxygen concentration distribution. It was found that the effect of the cell consumption on k(L)a could be negligible. A correlation was proposed to predict the liquid-phase oxygen transfer coefficient (k(Lm)) as a function of Re. The overall oxygen transfer coefficient (k(L)) was obtained by the two-resistance model. Another correlation, within an error of 15%, was proposed to estimate the minimum oxygen concentration to avoid cell hypoxia. By combination of the correlations, the maximum cell density, which the present micro-bioreactor could support, was predicted to be in the order of 10(12) cells m(-3). The results are comparable with typical values reported for animal cell growth in mechanically stirred bioreactors.
Collapse
Affiliation(s)
- P Yu
- Department of Mechanical Engineering, National University of Singapore, Singapore 117576, Singapore.
| | | | | | | |
Collapse
|
31
|
Goudar C, Joeris K, Cruz C, Zhang C, Konstantinov K. OUR AND CER ESTIMATION IN HIGH DENSITY MAMMALIAN CELL PERFUSION CULTURES. ACTA ACUST UNITED AC 2007. [DOI: 10.3182/20070604-3-mx-2914.00017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
32
|
|
33
|
Yang TH, Wittmann C, Heinzle E. Respirometric 13C flux analysis, Part I: design, construction and validation of a novel multiple reactor system using on-line membrane inlet mass spectrometry. Metab Eng 2006; 8:417-31. [PMID: 16844397 DOI: 10.1016/j.ymben.2006.03.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2005] [Revised: 03/09/2006] [Accepted: 03/16/2006] [Indexed: 11/30/2022]
Abstract
A novel method for (13)C flux analysis based on on-line CO(2) labeling measurements is presented. This so-called respirometric (13)C flux analysis requires multiple parallel (13)C labeling experiments using differently labeled tracer substrates. In Part I of the work, a membrane-inlet mass spectrometry-based measurement system with 6 parallel reactors with each 12 ml liquid volume and associated experimental and computational methods for the respirometric (13)C data acquisition and evaluation are described. Signal dynamics after switching between membrane probes follow exactly first-order allowing extrapolation to steady state. Each measurement cycle involving 3 reactors takes about 2 min. After development of a dynamic calibration method, the suitability and reliability of the analysis was examined with a lysine-producing mutant of Corynebacterium glutamicum using [1-(13)C(1)], [6-(13)C(1)], [1,6-(13)C(2)] glucose. Specific rates of oxygen uptake and CO(2) production were estimated with an error less than +/-0.3 mmol g(-1) h(-1) and had +/-3% to +/-10% deviations between parallel reactors which is primarily caused by inaccuracies in initial biomass concentration. The respiratory quotient could be determined with an uncertainty less than +/-0.02 and varied only +/-3% between reactors. Fractional labeling of CO(2) was estimated with much higher precision of about +/-0.001 to +/-0.005. The detailed statistical analysis suggested that these data should be of sufficient quality to allow physiological interpretation and metabolic flux estimation. The obtained data were applied for the respirometric (13)C metabolic flux analysis in Part II.
Collapse
Affiliation(s)
- Tae Hoon Yang
- Biochemical Engineering Institute, Saarland University, Bldg. A 1.5, Postbox 151150, D-66041 Saarbrücken, Germany
| | | | | |
Collapse
|
34
|
Yang Y, Balcarcel RR. Determination of carbon dioxide production rates for mammalian cells in 24-well plates. Biotechniques 2004; 36:286-90, 292, 294-5. [PMID: 14989093 DOI: 10.2144/04362rr03] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
In this report, we describe a method for the quantitative determination of carbon dioxide production rates of mammalian cells. Custom-made, reusable, optically clear plugs are used to seal the wells of a 24-well plate. These plugs prevent the loss of CO2 produced by the mammalian cells cultured in bicarbonate-free medium. Measurements of pH, total liquid phase CO2, and viable cell density are used to estimate the average CO2 production rate during a 6-h incubation period. Using this method, four chemicals well-characterized in regards to toxicity, 2,4-dinitrophenol, antimycin A, rotenone, and cyanide, were found to elicit significant changes in CO2 production for given concentrations within 6 h, without inducing a decline in culture viability. Over longer exposure times, similar concentrations caused growth inhibition but not cell death. An assay based on metabolic change corresponding to growth inhibition that is more sensitive than traditional measures of cell death is a feasible complement to existing methods in drug discovery and toxicity testing.
Collapse
|
35
|
Zieziulewicz TJ, Unfricht DW, Hadjout N, Lynes MA, Lawrence DA. Shrinking the biologic world--nanobiotechnologies for toxicology. Toxicol Sci 2003; 74:235-44. [PMID: 12832654 DOI: 10.1093/toxsci/kfg108] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Although toxicologic effects need to be considered at the organismal level, the adverse events originate from interactions and alterations at the molecular level. Cellular structures and functions can be disrupted by modifications of the nanometer structure of critical molecules; therefore, devices used to assess biologic and toxicologic processes at the nanoscale will allow important new research pursuits. In order to properly assess alterations at these dimensions, nanofabricated tools are needed to detect, separate, analyze, and manipulate cells or biologic molecules of interest. The emergence of laser tweezers, surface plasmon resonance (SPR), laser capture microdissection (LCM), atomic force microscopy (AFM), and multi-photon microscopes have allowed for these assessments. Micro- and nanobiotechnologies will further advance biologic, clinical, and toxicologic endeavors with the aid of miniaturized, more sensitive devices. Miniaturized table-top laboratory equipment incorporating additional innovative technologies can lead to new advances, including micro total analysis systems (microTAS) or "lab-on-a-chip" and "sentinel sensor" devices. This review will highlight several devices, which have been made possible by techniques originating in the microelectronics industry. These devices can be used for toxicologic assessment of cellular structures and functions, such as cellular adhesion, signal transduction, motility, deformability, metabolism, and secretion.
Collapse
Affiliation(s)
- Thomas J Zieziulewicz
- Laboratory of Clinical and Experimental Endocrinology and Immunology, Wadsworth Center, New York State Department of Health, Albany, New York 12201, USA
| | | | | | | | | |
Collapse
|
36
|
Yang TH, Wittmann C, Heinzle E. Dynamic calibration and dissolved gas analysis using membrane inlet mass spectrometry for the quantification of cell respiration. RAPID COMMUNICATIONS IN MASS SPECTROMETRY : RCM 2003; 17:2721-2731. [PMID: 14673819 DOI: 10.1002/rcm.1251] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A membrane inlet mass spectrometer connected to a miniaturized reactor was applied for dynamic dissolved gas analysis. Cell samples were taken from 7 mL shake flask cultures of Corynebacterium glutamicum ATCC 13032, and transferred to the 12 mL miniaturized reactor. There, oxygen uptake and carbon dioxide and its mass isotopomer production rates were determined using a new experimental procedure and applying nonlinear model equations. A novel dynamic method for the calibration of the membrane inlet mass spectrometer using first-order dynamics was developed. To derive total dissolved concentration of all carbon dioxide species (C(T)) from dissolved carbon dioxide concentration ([CO(2)](aq)), the ratio of C(T) to [CO(2)](aq) was determined by nonlinear parameter estimation, whereas the mass transfer coefficient of CO(2) was determined by the Wilke-Chang correlation. Subsequently, the suitability of the model equations for respiration measurements was examined using residual analysis and the Jarque-Bera hypothesis test. The resulting residuals were found to be random with normal distribution, which proved the adequacy of the application of the model for cell respiration analysis. Hence, dynamic changes in respiration activities could be accurately analyzed using membrane inlet mass spectrometry with the novel calibration method.
Collapse
Affiliation(s)
- Tae Hoon Yang
- Technische Biochemie, Saarland University, Im Stadtwald, Bldg. 2, D-66123 Saarbruecken, Germany
| | | | | |
Collapse
|