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Hoang MD, Doan DT, Schmidt M, Kranz H, Kremling A, Heins A. Application of an Escherichia coli triple reporter strain for at-line monitoring of single-cell physiology during L-phenylalanine production. Eng Life Sci 2023; 23:e2100162. [PMID: 36619877 PMCID: PMC9815085 DOI: 10.1002/elsc.202100162] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/24/2022] [Accepted: 02/07/2022] [Indexed: 01/11/2023] Open
Abstract
Biotechnological production processes are sustainable approaches for the production of biobased components such as amino acids for food and feed industry. Scale-up from ideal lab-scale bioreactors to large-scale processes is often accompanied by loss in productivity. This may be related to population heterogeneities of cells originating from isogenic cultures that arise due to dynamic non-ideal conditions in the bioreactor. To better understand this phenomenon, deeper insights into single-cell physiologies in bioprocesses are mandatory before scale-up. Here, a triple reporter strain (3RP) was developed by chromosomally integrating the fluorescent proteins mEmerald, CyOFP1, and mTagBFP2 into the L-phenylalanine producing Escherichia coli strain FUS4 (pF81kan) to allow monitoring of growth, oxygen availability, and general stress response of the single cells. Functionality of the 3RP was confirmed in well-mixed lab-scale fed-batch processes with glycerol as carbon source in comparison to the strain without fluorescent proteins, leading to no difference in process performance. Fluorescence levels could successfully reflect the course of related process state variables, revealed population heterogeneities during the transition between different process phases and potentially subpopulations that exhibit superior process performance. Furthermore, indications were found for noise in gene expression as regulation strategy against environmental perturbation.
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Affiliation(s)
- Manh Dat Hoang
- Chair of Biochemical EngineeringDepartment of Energy and Process EngineeringTUM School of Engineering and DesignTechnical University of MunichGarchingGermany
| | - Dieu Thi Doan
- Systems BiotechnologyDepartment of Energy and Process EngineeringTUM School of Engineering and DesignTechnical University of MunichGarchingGermany
| | - Marlen Schmidt
- Gen‐H Genetic Engineering Heidelberg GmbHHeidelbergGermany
| | - Harald Kranz
- Gen‐H Genetic Engineering Heidelberg GmbHHeidelbergGermany
| | - Andreas Kremling
- Systems BiotechnologyDepartment of Energy and Process EngineeringTUM School of Engineering and DesignTechnical University of MunichGarchingGermany
| | - Anna‐Lena Heins
- Chair of Biochemical EngineeringDepartment of Energy and Process EngineeringTUM School of Engineering and DesignTechnical University of MunichGarchingGermany
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Heins A, Hoang MD, Weuster‐Botz D. Advances in automated real-time flow cytometry for monitoring of bioreactor processes. Eng Life Sci 2022; 22:260-278. [PMID: 35382548 PMCID: PMC8961054 DOI: 10.1002/elsc.202100082] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 10/22/2021] [Accepted: 10/27/2021] [Indexed: 12/18/2022] Open
Abstract
Flow cytometry and its technological possibilities have greatly advanced in the past decade as analysis tool for single cell properties and population distributions of different cell types in bioreactors. Along the way, some solutions for automated real-time flow cytometry (ART-FCM) were developed for monitoring of bioreactor processes without operator interference over extended periods with variable sampling frequency. However, there is still great potential for ART-FCM to evolve and possibly become a standard application in bioprocess monitoring and process control. This review first addresses different components of an ART-FCM, including the sampling device, the sample-processing unit, the unit for sample delivery to the flow cytometer and the settings for measurement of pre-processed samples. Also, available algorithms are presented for automated data analysis of multi-parameter fluorescence datasets derived from ART-FCM experiments. Furthermore, challenges are discussed for integration of fluorescence-activated cell sorting into an ART-FCM setup for isolation and separation of interesting subpopulations that can be further characterized by for instance omics-methods. As the application of ART-FCM is especially of interest for bioreactor process monitoring, including investigation of population heterogeneity and automated process control, a summary of already existing setups for these purposes is given. Additionally, the general future potential of ART-FCM is addressed.
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Affiliation(s)
- Anna‐Lena Heins
- Institute of Biochemical EngineeringTechnical University of MunichGarchingGermany
| | - Manh Dat Hoang
- Institute of Biochemical EngineeringTechnical University of MunichGarchingGermany
| | - Dirk Weuster‐Botz
- Institute of Biochemical EngineeringTechnical University of MunichGarchingGermany
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Zalai D, Kopp J, Kozma B, Küchler M, Herwig C, Kager J. Microbial technologies for biotherapeutics production: Key tools for advanced biopharmaceutical process development and control. DRUG DISCOVERY TODAY. TECHNOLOGIES 2021; 38:9-24. [PMID: 34895644 DOI: 10.1016/j.ddtec.2021.04.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 03/14/2021] [Accepted: 04/06/2021] [Indexed: 12/26/2022]
Abstract
Current trends in the biopharmaceutical market such as the diversification of therapies as well as the increasing time-to-market pressure will trigger the rethinking of bioprocess development and production approaches. Thereby, the importance of development time and manufacturing costs will increase, especially for microbial production. In the present review, we investigate three technological approaches which, to our opinion, will play a key role in the future of biopharmaceutical production. The first cornerstone of process development is the generation and effective utilization of platform knowledge. Building processes on well understood microbial and technological platforms allows to accelerate early-stage bioprocess development and to better condense this knowledge into multi-purpose technologies and applicable mathematical models. Second, the application of verified scale down systems and in silico models for process design and characterization will reduce the required number of large scale batches before dossier submission. Third, the broader availability of mathematical process models and the improvement of process analytical technologies will increase the applicability and acceptance of advanced control and process automation in the manufacturing scale. This will reduce process failure rates and subsequently cost of goods. Along these three aspects we give an overview of recently developed key tools and their potential integration into bioprocess development strategies.
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Affiliation(s)
- Denes Zalai
- Richter-Helm BioLogics GmbH & Co. KG, Suhrenkamp 59, 22335 Hamburg, Germany.
| | - Julian Kopp
- Research Division Biochemical Engineering, Institute of Chemical Environmental and Bioscience Engineering, Vienna University of Technology, Vienna, Austria
| | - Bence Kozma
- Research Division Biochemical Engineering, Institute of Chemical Environmental and Bioscience Engineering, Vienna University of Technology, Vienna, Austria
| | - Michael Küchler
- Richter-Helm BioLogics GmbH & Co. KG, Suhrenkamp 59, 22335 Hamburg, Germany
| | - Christoph Herwig
- Research Division Biochemical Engineering, Institute of Chemical Environmental and Bioscience Engineering, Vienna University of Technology, Vienna, Austria; Competence Center CHASE GmbH, Altenbergerstraße 69, 4040 Linz, Austria
| | - Julian Kager
- Research Division Biochemical Engineering, Institute of Chemical Environmental and Bioscience Engineering, Vienna University of Technology, Vienna, Austria
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Huttanus HM, Senger RS. A synthetic biosensor to detect peroxisomal acetyl-CoA concentration for compartmentalized metabolic engineering. PeerJ 2020; 8:e9805. [PMID: 33194349 PMCID: PMC7485502 DOI: 10.7717/peerj.9805] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Accepted: 08/03/2020] [Indexed: 11/20/2022] Open
Abstract
Background Sub-cellular compartmentalization is used by cells to create favorable microenvironments for various metabolic reactions. These compartments concentrate enzymes, separate competing metabolic reactions, and isolate toxic intermediates. Such advantages have been recently harnessed by metabolic engineers to improve the production of various high-value chemicals via compartmentalized metabolic engineering. However, measuring sub-cellular concentrations of key metabolites represents a grand challenge for compartmentalized metabolic engineering. Methods To this end, we developed a synthetic biosensor to measure a key metabolite, acetyl-CoA, in a representative compartment of yeast, the peroxisome. This synthetic biosensor uses enzyme re-localization via PTS1 signal peptides to construct a metabolic pathway in the peroxisome which converts acetyl-CoA to polyhydroxybutyrate (PHB) via three enzymes. The PHB is then quantified by HPLC. Results The biosensor demonstrated the difference in relative peroxisomal acetyl-CoA availability under various culture conditions and was also applied to screening a library of single knockout yeast mutants. The screening identified several mutants with drastically reduced peroxisomal acetyl-CoA and one with potentially increased levels. We expect our synthetic biosensors can be widely used to investigate sub-cellular metabolism and facilitate the “design-build-test” cycle of compartmentalized metabolic engineering.
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Affiliation(s)
- Herbert M Huttanus
- Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, United States of America
| | - Ryan S Senger
- Department of Biological Systems Engineering, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, United States of America.,Department of Chemical Engineering, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, United States of America
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Importance of the cultivation history for the response of Escherichia coli to oscillations in scale-down experiments. Bioprocess Biosyst Eng 2018; 41:1305-1313. [PMID: 29808419 DOI: 10.1007/s00449-018-1958-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 05/23/2018] [Indexed: 10/14/2022]
Abstract
Large-scale bioreactors are inhomogeneous systems, in which the fluid phase expresses concentration gradients. They depend on the mass transfer and fluid dynamics in the reactor, the feeding strategy, the cell-specific substrate uptake parameters, and the cell density. As high cell densities are only obtained at low specific growth rates, it is necessary to investigate the cellular responses to oscillations in particular under such conditions, an issue which is mostly neglected. Instead, the feed oscillations are often started directly after the batch phase, when the specific growth rate is close to the maximum. We show here that the cultivation mode before oscillations are started has a tremendous effect on the metabolic responses. In difference to cells, which were pre-grown under batch conditions at a high growth rate, Escherichia coli cells that were pre-grown under glucose limitation at a low growth rate accumulate short-chain fatty acids (acetate, lactate, succinate) and glycolysis-related amino acids to a higher extent in a two-compartment scale-down bioreactor. Thus, cells which enter oscillations from a lower specific growth rate seem to react more sensitive to oscillations than cells that are subjected to oscillations directly after a batch phase. These results are interesting in designing reliable scale-down systems, which better reflect large-scale bioprocesses.
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Heins AL, Weuster-Botz D. Population heterogeneity in microbial bioprocesses: origin, analysis, mechanisms, and future perspectives. Bioprocess Biosyst Eng 2018. [PMID: 29541890 DOI: 10.1007/s00449-018-1922-3] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Population heterogeneity is omnipresent in all bioprocesses even in homogenous environments. Its origin, however, is only so well understood that potential strategies like bet-hedging, noise in gene expression and division of labour that lead to population heterogeneity can be derived from experimental studies simulating the dynamics in industrial scale bioprocesses. This review aims at summarizing the current state of the different parts of single cell studies in bioprocesses. This includes setups to visualize different phenotypes of single cells, computational approaches connecting single cell physiology with environmental influence and special cultivation setups like scale-down reactors that have been proven to be useful to simulate large-scale conditions. A step in between investigation of populations and single cells is studying subpopulations with distinct properties that differ from the rest of the population with sub-omics methods which are also presented here. Moreover, the current knowledge about population heterogeneity in bioprocesses is summarized for relevant industrial production hosts and mixed cultures, as they provide the unique opportunity to distribute metabolic burden and optimize production processes in a way that is impossible in traditional monocultures. In the end, approaches to explain the underlying mechanism of population heterogeneity and the evidences found to support each hypothesis are presented. For instance, population heterogeneity serving as a bet-hedging strategy that is used as coordinated action against bioprocess-related stresses while at the same time spreading the risk between individual cells as it ensures the survival of least a part of the population in any environment the cells encounter.
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Affiliation(s)
- Anna-Lena Heins
- Institute of Biochemical Engineering, Technical University of Munich, Boltzmannstr. 15, 85748, Garching, Germany.
| | - Dirk Weuster-Botz
- Institute of Biochemical Engineering, Technical University of Munich, Boltzmannstr. 15, 85748, Garching, Germany
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González-Cabaleiro R, Mitchell AM, Smith W, Wipat A, Ofiţeru ID. Heterogeneity in Pure Microbial Systems: Experimental Measurements and Modeling. Front Microbiol 2017; 8:1813. [PMID: 28970826 PMCID: PMC5609101 DOI: 10.3389/fmicb.2017.01813] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Accepted: 09/05/2017] [Indexed: 01/02/2023] Open
Abstract
Cellular heterogeneity influences bioprocess performance in ways that until date are not completely elucidated. In order to account for this phenomenon in the design and operation of bioprocesses, reliable analytical and mathematical descriptions are required. We present an overview of the single cell analysis, and the mathematical modeling frameworks that have potential to be used in bioprocess control and optimization, in particular for microbial processes. In order to be suitable for bioprocess monitoring, experimental methods need to be high throughput and to require relatively short processing time. One such method used successfully under dynamic conditions is flow cytometry. Population balance and individual based models are suitable modeling options, the latter one having in particular a good potential to integrate the various data collected through experimentation. This will be highly beneficial for appropriate process design and scale up as a more rigorous approach may prevent a priori unwanted performance losses. It will also help progressing synthetic biology applications to industrial scale.
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Affiliation(s)
- Rebeca González-Cabaleiro
- School of Engineering, Chemical Engineering, Newcastle UniversityNewcastle upon Tyne, United Kingdom
| | - Anca M Mitchell
- School of Engineering, Chemical Engineering, Newcastle UniversityNewcastle upon Tyne, United Kingdom
| | - Wendy Smith
- Interdisciplinary Computing and Complex BioSystems (ICOS), School of ComputingNewcastle University, Newcastle upon Tyne, United Kingdom
| | - Anil Wipat
- Interdisciplinary Computing and Complex BioSystems (ICOS), School of ComputingNewcastle University, Newcastle upon Tyne, United Kingdom
| | - Irina D Ofiţeru
- School of Engineering, Chemical Engineering, Newcastle UniversityNewcastle upon Tyne, United Kingdom
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8
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Jaén KE, Sigala JC, Olivares-Hernández R, Niehaus K, Lara AR. Heterogeneous oxygen availability affects the titer and topology but not the fidelity of plasmid DNA produced by Escherichia coli. BMC Biotechnol 2017; 17:60. [PMID: 28676110 PMCID: PMC5496438 DOI: 10.1186/s12896-017-0378-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2017] [Accepted: 06/22/2017] [Indexed: 12/13/2022] Open
Abstract
Background Dissolved oxygen tension (DOT) is hardly constant and homogenously distributed in a bioreactor, which can have a negative impact in the metabolism and product synthesis. However, the effects of DOT on plasmid DNA (pDNA) production and quality have not been thoroughly investigated. In the present study, the effects of aerobic (DOT ≥30% air sat.), microaerobic (constant DOT = 3% air sat.) and oscillatory DOT (from 0 to 100% air sat.) conditions on pDNA production, quality and host performance were characterized. Results Microaerobic conditions had little effect on pDNA production, supercoiled fraction and sequence fidelity. By contrast, oscillatory DOT caused a 22% decrease in pDNA production compared with aerobic cultures. Although in aerobic cultures the pDNA supercoiled fraction was 98%, it decreased to 80% under heterogeneous DOT conditions. The different oxygen availabilities had no effect on the fidelity of the produced pDNA. The estimated metabolic fluxes indicated substantial differences at the level of the pentose phosphate pathway and TCA cycle under different conditions. Cyclic changes in fermentative pathway fluxes, as well as fast shifts in the fluxes through cytochromes, were also estimated. Model-based genetic modifications that can potentially improve the process performance are suggested. Conclusions DOT heterogeneities strongly affected cell performance, pDNA production and topology. This should be considered when operating or scaling-up a bioreactor with deficient mixing. Constant microaerobic conditions affected the bacterial metabolism but not the amount or quality of pDNA. Therefore, pDNA production in microaerobic cultures may be an alternative for bioreactor operation at higher oxygen transfer rates. Electronic supplementary material The online version of this article (doi:10.1186/s12896-017-0378-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Karim E Jaén
- Posgrado en Ciencias Naturales e Ingeniería, Universidad Autónoma Metropolita-Cuajimalpa, Av. Vasco de Quiroga 4871, Col. Santa Fe, 05348, Mexico City, Mexico
| | - Juan-Carlos Sigala
- Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa, Av. Vasco de Quiroga 4871, Col. Santa Fe, 05348, Mexico City, Mexico
| | - Roberto Olivares-Hernández
- Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa, Av. Vasco de Quiroga 4871, Col. Santa Fe, 05348, Mexico City, Mexico
| | - Karsten Niehaus
- Abteilung für Proteom- und Metabolomforschung, Fakultät für Biologie & CeBiTec, Universität Bielefeld, Universitätsstr. 25, 33615, Bielefeld, Germany
| | - Alvaro R Lara
- Departamento de Procesos y Tecnología, Universidad Autónoma Metropolitana-Cuajimalpa, Av. Vasco de Quiroga 4871, Col. Santa Fe, 05348, Mexico City, Mexico.
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High-throughput strategies for the discovery and engineering of enzymes for biocatalysis. Bioprocess Biosyst Eng 2016; 40:161-180. [DOI: 10.1007/s00449-016-1690-x] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 10/05/2016] [Indexed: 12/16/2022]
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Genetically-encoded biosensors for monitoring cellular stress in bioprocessing. Curr Opin Biotechnol 2015; 31:50-6. [DOI: 10.1016/j.copbio.2014.07.011] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 07/30/2014] [Indexed: 12/15/2022]
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Faust G, Janzen NH, Bendig C, Römer L, Kaufmann K, Weuster-Botz D. Feeding strategies enhance high cell density cultivation and protein expression in milliliter scale bioreactors. Biotechnol J 2014; 9:1293-303. [DOI: 10.1002/biot.201400346] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 07/18/2014] [Accepted: 08/05/2014] [Indexed: 12/23/2022]
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Alloue-Boraud WAM, N'Guessan KF, Djeni NT, Hiligsmann S, Djè KM, Delvigne F. Fermentation profile of Saccharomyces cerevisiae and Candida tropicalis as starter cultures on barley malt medium. Journal of Food Science and Technology 2014; 52:5236-42. [PMID: 26243947 DOI: 10.1007/s13197-014-1526-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 08/12/2014] [Accepted: 08/15/2014] [Indexed: 11/28/2022]
Abstract
Saccharomyces cerevisiae C8-5 and Candida tropicalis F0-5 isolated from traditional sorghum beer were tested for kinetic parameters on barley malt extract, YPD (863 medium) and for alcohol production. The results showed that C. tropicalis has the highest maximum growth rate and the lowest doubling time. Values were 0.22 and 0.32 h(-1) for maximum growth rate, 3 h 09 min and 2 h 09 min for doubling time respectively on barley malt extract and YPD. On contrary, glucose consumption was the fastest with S. cerevisiae (-0.36 and -0.722 g/l/h respectively on barley malt extract and YPD). When these two yeasts were used as starters in pure culture and co-culture at proportion of 1:1 and 2:1 (cell/cell) for barley malt extract fermentation, we noticed that maltose content increased first from 12.12 g/l to 13.62-16.46 g/l and then decreased. The highest increase was obtained with starter C. tropicalis + S. cerevisiae 2:1. On contrary, glucose content decreased throughout all the fermentation process. For all the starters used, the major part of the ethanol was produced at 16 h of fermentation. Values obtained in the final beers were 11.4, 11.6, 10.4 and 10.9 g/l for fermentation conducted with S. cerevisiae, C. tropicalis, C. tropicalis + S. cerevisiae 1:1 and C. tropicalis + S. cerevisiae 2:1. Cell viability measurement during the fermentation by using flow cytometry revealed that the lowest mean channel fluorescence for FL3 (yeast rate of death) was obtained with C. tropicalis + S. cerevisiae 2:1 after 48 h of fermentation.
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Affiliation(s)
- Wazé Aimée Mireille Alloue-Boraud
- Centre Wallon de Biologie Industrielle (CWBI) Unité de Bio-industries, Université de Liège, Gembloux Agrobio-Tech, Passage des Déportés 2, 5030 Gembloux, Belgium ; Laboratoire de Biotechnologie et Microbiologie des Aliments, UFR-STA, Université Nangui Abrogoua, 02 BP 801, Abidjan 02, Côte d'Ivoire
| | - Kouadio Florent N'Guessan
- Laboratoire de Biotechnologie et Microbiologie des Aliments, UFR-STA, Université Nangui Abrogoua, 02 BP 801, Abidjan 02, Côte d'Ivoire
| | - N'Dédé Théodore Djeni
- Laboratoire de Biotechnologie et Microbiologie des Aliments, UFR-STA, Université Nangui Abrogoua, 02 BP 801, Abidjan 02, Côte d'Ivoire
| | - Serge Hiligsmann
- Centre Wallon de Biologie Industrielle, Bd du Rectorat, 29, B.40 - P.70, 4000 Liège, Belgium
| | - Koffi Marcellin Djè
- Laboratoire de Biotechnologie et Microbiologie des Aliments, UFR-STA, Université Nangui Abrogoua, 02 BP 801, Abidjan 02, Côte d'Ivoire
| | - Franck Delvigne
- Centre Wallon de Biologie Industrielle (CWBI) Unité de Bio-industries, Université de Liège, Gembloux Agrobio-Tech, Passage des Déportés 2, 5030 Gembloux, Belgium
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Brognaux A, Han S, Sørensen SJ, Lebeau F, Thonart P, Delvigne F. A low-cost, multiplexable, automated flow cytometry procedure for the characterization of microbial stress dynamics in bioreactors. Microb Cell Fact 2013; 12:100. [PMID: 24176169 PMCID: PMC4228430 DOI: 10.1186/1475-2859-12-100] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2013] [Accepted: 10/30/2013] [Indexed: 12/20/2022] Open
Abstract
Background Microbial cell population heterogeneity is now recognized as a major source of issues in the development and optimization of bioprocesses. Even if single cell technologies are available for the study of microbial population heterogeneity, only a few of these methods are available in order to study the dynamics of segregation directly in bioreactors. In this context, specific interfaces have been developed in order to connect a flow cytometer directly to a bioreactor for automated analyses. In this work, we propose a simplified version of such an interface and demonstrate its usefulness for multiplexed experiments. Results A low-cost automated flow cytometer has been used in order to monitor the synthesis of a destabilized Green Fluorescent Protein (GFP) under the regulation of the fis promoter and propidium iodide (PI) uptake. The results obtained showed that the dynamics of GFP synthesis are complex and can be attributed to a complex set of biological parameters, i.e. on the one hand the release of protein into the extracellular medium and its uptake modifying the activity of the fis promoter, and on the other hand the stability of the GFP molecule itself, which can be attributed to the protease content and energy status of the cells. In this respect, multiplexed experiments have shown a correlation between heat shock and ATP content and the stability of the reporter molecule. Conclusion This work demonstrates that a simplified version of on-line FC can be used at the process level or in a multiplexed version to investigate the dynamics of complex physiological mechanisms. In this respect, the determination of new on-line parameters derived from automated FC is of primary importance in order to fully integrate the power of FC in dedicated feedback control loops.
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Affiliation(s)
| | | | | | | | | | - Frank Delvigne
- Unité de Bio-industries/CWBI, Gembloux Agro-Bio Tech, Université de Liège, Passage des Déportés 2, Gembloux 5030, Belgium.
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Cai Z, Kastell A, Knorr D, Smetanska I. Exudation: an expanding technique for continuous production and release of secondary metabolites from plant cell suspension and hairy root cultures. PLANT CELL REPORTS 2012; 31:461-477. [PMID: 21987121 DOI: 10.1007/s00299-011-1165-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2011] [Revised: 09/24/2011] [Accepted: 09/25/2011] [Indexed: 05/31/2023]
Abstract
This review addresses methods of obtaining secondary metabolites from plant cell suspension and hairy root cultures and their exudates, particularly the physiological mechanisms of secondary metabolites release and trafficking. The efficiency for product recovery of metabolites can be increased by various methods, based on the principle of continuous product release into the cultivation medium. The most common methods for metabolite recovery are elicitation, influencing membrane permeability, and in situ product removal. The biosynthetic pathways can be influenced by cultivation conditions, transformation, or application of elicitors. The membrane permeability can be altered through the application of chemical or physical treatments. Product removal can be greatly increased through a two-phase system and the introduction of absorbents into the cultivation medium. In this review, we describe some improved approaches that have proven useful in these efforts.
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Affiliation(s)
- Zhenzhen Cai
- Institute of Food Biotechnology and Food Chemistry, Berlin University of Technology, Königin-Luise Str. 22, 14195 Berlin, Germany.
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