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Movahedpour A, Ahmadi N, Ghalamfarsa F, Ghesmati Z, Khalifeh M, Maleksabet A, Shabaninejad Z, Taheri-Anganeh M, Savardashtaki A. β-Galactosidase: From its source and applications to its recombinant form. Biotechnol Appl Biochem 2021; 69:612-628. [PMID: 33656174 DOI: 10.1002/bab.2137] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 02/19/2021] [Indexed: 12/12/2022]
Abstract
Carbohydrate-active enzymes are a group of important enzymes playing a critical role in the degradation and synthesis of carbohydrates. Glycosidases can hydrolyze glycosides into oligosaccharides, polysaccharides, and glycoconjugates via a cost-effective approach. Lactase is an important member of β-glycosidases found in higher plants, animals, and microorganisms. β-Galactosidases can be used to degrade the milk lactose for making lactose-free milk, which is sweeter than regular milk and is suitable for lactose-intolerant people. β-Galactosidase is employed by many food industries to degrade lactose and improve the digestibility, sweetness, solubility, and flavor of dairy products. β-Galactosidase enzymes have various families and are applied in the food-processing industries such as hydrolyzed-milk products, whey, and galactooligosaccharides. Thus, this enzyme is a valuable protein which is now produced by recombinant technology. In this review, origins, structure, recombinant production, and critical modifications of β-galactosidase for improving the production process are discussed. Since β-galactosidase is a valuable enzyme in industry and health care, a study of its various aspects is important in industrial biotechnology and applied biochemistry.
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Affiliation(s)
- Ahmad Movahedpour
- Department of Medical Biotechnology, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran.,Student Research Committee, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Nahid Ahmadi
- Department of Medical Biotechnology, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Farideh Ghalamfarsa
- Department of Medical Biotechnology, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Zeinab Ghesmati
- Department of Medical Biotechnology, School of Advanced Medical Sciences, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Masoomeh Khalifeh
- Department of Medical Biotechnology, School of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - Amir Maleksabet
- Department of Medical Biotechnology, School of Advanced Technologies in Medicine, Mazandaran University of Medical Sciences, Sari, Iran
| | - Zahra Shabaninejad
- Department of Nanobiotechnology, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.,Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Mortaza Taheri-Anganeh
- Shahid Arefian Hospital, Urmia, Iran.,Cellular and Molecular Research Center, Cellular and Molecular Medicine Institute, Urmia University of Medical Sciences, Urmia, Iran
| | - Amir Savardashtaki
- Department of Medical Biotechnology, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran.,Pharmaceutical Sciences Research Center, Shiraz University of Medical Sciences, Shiraz, Iran
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2
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Zamyatina AV, Rudenko NV, Karatovskaya AP, Shepelyakovskaya AO, Siunov AV, Andreeva-Kovalevskaya ZI, Nagel AS, Salyamov VI, Kolesnikov AS, Brovko FA, Solonin AS. Monoclonal Antibody HlyIIC‑15 to C-End Domain HlyII B. cereus Interacts with the Trombin Recognition Site. RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY 2020; 46:1214-1220. [PMID: 33390685 PMCID: PMC7768993 DOI: 10.1134/s1068162020060382] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 05/08/2020] [Accepted: 05/11/2020] [Indexed: 11/23/2022]
Abstract
Among the panel of monoclonal antibodies to the recombinant protein HlyIICTD Bacillus cereus an antibody was found capable of forming an immune complex with a thrombin recognition region, the amino acid sequence of which is located inside the recombinant HlyIICTD. Localization of the epitope was carried out using peptide phage display methods, as well as enzyme immunoassay and immunoblotting for interaction with recombinant proteins, either containing or not containing individual components HlyIICTD. The identified epitope is located in the region of the thrombin site and retains the ability to interact with the antibody after the proteolyotic attack of the protein by thrombin.
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Affiliation(s)
- A. V. Zamyatina
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Pushchino Branch, Russian Academy of Sciences, Pushchino, Moscow oblast 142290 Russia
- Pushchino State Natural Science Institute, Pushchino, Moscow oblast 142290 Russia
| | - N. V. Rudenko
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Pushchino Branch, Russian Academy of Sciences, Pushchino, Moscow oblast 142290 Russia
| | - A. P. Karatovskaya
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Pushchino Branch, Russian Academy of Sciences, Pushchino, Moscow oblast 142290 Russia
| | - A. O. Shepelyakovskaya
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Pushchino Branch, Russian Academy of Sciences, Pushchino, Moscow oblast 142290 Russia
| | - A. V. Siunov
- Scryabin Institute of Biochemistry and Physiology of Microorganisms, Scientific Center for Biological Research, Russian Academy of Sciences, Pushchino, Moscow oblast 142290 Russia
| | - Zh. I. Andreeva-Kovalevskaya
- Scryabin Institute of Biochemistry and Physiology of Microorganisms, Scientific Center for Biological Research, Russian Academy of Sciences, Pushchino, Moscow oblast 142290 Russia
| | - A. S. Nagel
- Scryabin Institute of Biochemistry and Physiology of Microorganisms, Scientific Center for Biological Research, Russian Academy of Sciences, Pushchino, Moscow oblast 142290 Russia
| | - V. I. Salyamov
- Scryabin Institute of Biochemistry and Physiology of Microorganisms, Scientific Center for Biological Research, Russian Academy of Sciences, Pushchino, Moscow oblast 142290 Russia
| | - A. S. Kolesnikov
- Scryabin Institute of Biochemistry and Physiology of Microorganisms, Scientific Center for Biological Research, Russian Academy of Sciences, Pushchino, Moscow oblast 142290 Russia
| | - F. A. Brovko
- Shemyakin–Ovchinnikov Institute of Bioorganic Chemistry, Pushchino Branch, Russian Academy of Sciences, Pushchino, Moscow oblast 142290 Russia
- Pushchino State Natural Science Institute, Pushchino, Moscow oblast 142290 Russia
| | - A. S. Solonin
- Scryabin Institute of Biochemistry and Physiology of Microorganisms, Scientific Center for Biological Research, Russian Academy of Sciences, Pushchino, Moscow oblast 142290 Russia
- Pushchino State Natural Science Institute, Pushchino, Moscow oblast 142290 Russia
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3
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McKay R, Hauk P, Quan D, Bentley WE. Development of Cell-Based Sentinels for Nitric Oxide: Ensuring Marker Expression and Unimodality. ACS Synth Biol 2018; 7:1694-1701. [PMID: 29975512 PMCID: PMC7025431 DOI: 10.1021/acssynbio.8b00146] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
We generated "sentinel" bacteria that respond to the biomarker nitric oxide (NO) and produce a homogeneous and strong fluorescent response. Our dual-plasmid system consists of a signal "relay" vector that employs an NO-responsive promoter that amplifies the native signal (via expression of T7 Polymerase (T7Pol)) to a second vector responsible for GFP expression. Importantly, to achieve an optimal "sentinel" response, we developed strategies that balance the transcriptional load within cells by altering (i) translation and (ii) activity of the T7Pol. Our optimized genetic circuitry was then used to transform commensal E. coli Nissle, as a proof-of-concept toward an ingestible cell-based sensor for Crohn's disease (CD) that, in turn, is marked by elevated levels of intestinal NO. Thus, the "biosensors" demonstrated here may serve as a simple diagnostic tool, contrasting the standard of care including colonoscopies or biopsies.
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Affiliation(s)
- Ryan McKay
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
- Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, Maryland 20742, United States
| | - Pricila Hauk
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
- Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, Maryland 20742, United States
| | - David Quan
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
- Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, Maryland 20742, United States
| | - William E. Bentley
- Fischell Department of Bioengineering, University of Maryland, College Park, Maryland 20742, United States
- Institute for Bioscience and Biotechnology Research, University of Maryland, College Park, Maryland 20742, United States
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4
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Albers SC, Gallegos VA, Peebles CAM. Engineering of genetic control tools in Synechocystis sp. PCC 6803 using rational design techniques. J Biotechnol 2015; 216:36-46. [PMID: 26450561 DOI: 10.1016/j.jbiotec.2015.09.042] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2015] [Revised: 09/17/2015] [Accepted: 09/29/2015] [Indexed: 12/01/2022]
Abstract
Cyanobacteria show promise as photosynthetic microbial factories capable of harnessing sunlight and CO2 to produce valuable end products, but few genetic control tools have been characterized and utilized in these organisms. To develop a suite of control elements capable of gene control at a variety of expression strengths, a library of 10 promoter-constructs were developed and built via rational design techniques by adding individual nucleotides in a step-wise manner within the -10 and -35 cis-acting regions of the tac promoter. This suite produced a dynamic range of expression strength, exhibiting a 78 fold change between the lowest expressing promoter, Psca8- and the highest expressing promoter, Psca3-2 when tested within Synechocystis sp. PCC 6803. Additionally, this study details the construction of a chemically inducible construct for use in Synechocystis that is based on the tac repressor system most commonly used in Escherichia coli. This research demonstrates the construction of a highly expressed inducible promoter that is also capable of high levels of gene repression. Upon chemical induction with IPTG, this same mutant strain was capable of exhibiting an average 24X increase in GFP expression over that of the repressed state.
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Affiliation(s)
- Stevan C Albers
- Cell and Molecular Biology Graduate Program, Colorado State University, 1005 Campus Delivery, Fort Collins, CO 80523, USA.
| | - Victor A Gallegos
- Department of Biochemistry and Molecular Biology, Colorado State University, 1870 Campus Delivery, Fort Collins, CO 80523, USA; Department of Chemical and Biological Engineering, Colorado State University, 1370 Campus Delivery, Fort Collins, CO 80523, USA.
| | - Christie A M Peebles
- Cell and Molecular Biology Graduate Program, Colorado State University, 1005 Campus Delivery, Fort Collins, CO 80523, USA; Department of Chemical and Biological Engineering, Colorado State University, 1370 Campus Delivery, Fort Collins, CO 80523, USA.
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5
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Martín-López A, Acosta-López L, García-Camacho F, Contreras-Gómez A, Molina-Grima E. Co-culture of the 55-6 B cell hybridoma with the EL-4 thymoma cell. Effect on cell growth and monoclonal antibody production. Cytotechnology 2013; 65:655-62. [PMID: 23765215 DOI: 10.1007/s10616-013-9593-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 05/31/2013] [Indexed: 12/21/2022] Open
Abstract
The cell growth and monoclonal antibody production of the 55-6 hybridoma cell co-cultured with the murine thymoma cell line EL-4 at different initial 55-6:EL-4 ratios were investigated. Both populations were seeded in co-culture without previous stimulation and therefore with low constitutive CD40 and CD40 ligand (CD154) expression levels, and in the absence of exogenous co-stimuli. Viable cell density and growth rate data seem to suggest a competition for nutrients, which is detrimental for both cells in terms of biomass production and also of growth rate for 55-6. Final concentrations of antibody and specific antibody production rates were affected by the initial 55-6:EL-4 ratio. The 4:1 ratio yielded the highest IgG2a concentration, whereas the highest specific antibody production rate was obtained at the 2:1 ratio. Changes mainly in CD154 and also in CD40 expression in co-cultures could suggest cross-talk between both populations. In conclusion, different types of interactions are probably present in this co-culture system: competition for nutrients, cognate interaction and/or autocrine or paracrine interactions that influence the proliferation of both cells and the hybridoma antibody secretion. We are hereby presenting a pre-scale-up process that could speed up the optimization of large-scale monoclonal antibodies production in bioreactors by emulating the in vivo cell-cell interaction between B and T cells without previous stimulation or the addition of co-stimulatory molecules.
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6
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Silva F, Queiroz JA, Domingues FC. Evaluating metabolic stress and plasmid stability in plasmid DNA production by Escherichia coli. Biotechnol Adv 2012; 30:691-708. [DOI: 10.1016/j.biotechadv.2011.12.005] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2011] [Revised: 12/01/2011] [Accepted: 12/29/2011] [Indexed: 01/26/2023]
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7
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Alfasi S, Sevastsyanovich Y, Zaffaroni L, Griffiths L, Hall R, Cole J. Use of GFP fusions for the isolation of Escherichia coli strains for improved production of different target recombinant proteins. J Biotechnol 2011; 156:11-21. [DOI: 10.1016/j.jbiotec.2011.08.016] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2010] [Revised: 06/03/2011] [Accepted: 08/08/2011] [Indexed: 11/28/2022]
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8
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Shitu JO, Woodley JM, Wnek R, Chartrain M, Hewitt CJ. Induction studies with Escherichia coli expressing recombinant interleukin-13 using multi-parameter flow cytometry. Biotechnol Lett 2009; 31:577-84. [PMID: 19125223 DOI: 10.1007/s10529-008-9908-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2008] [Accepted: 12/09/2008] [Indexed: 11/24/2022]
Abstract
The expression of interleukin-13 (IL13) following induction with IPTG in Escherichia coli results in metabolic changes as indicated by multi-parameter flow cytometry and traditional methods of fermentation profiling (O2 uptake rate, CO2 evolution rate and optical density measurements). Induction early in the rapid growth phase was optimal although this led to lower overall biomass concentrations and lower maximum specific growth rates. In contrast, induction in the mid-rapid growth phase was the most detrimental to cell quality as measured by cytoplamsic membrane depolarisation.
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Affiliation(s)
- Jennifer O Shitu
- Department of Biochemical Engineering, University College London, Torrington Place, London WC1E7JE, UK
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9
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Lee SK, Keasling JD. Heterologous protein production in Escherichia coli using the propionate-inducible pPro system by conventional and auto-induction methods. Protein Expr Purif 2008; 61:197-203. [PMID: 18639640 DOI: 10.1016/j.pep.2008.06.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2008] [Revised: 06/16/2008] [Accepted: 06/17/2008] [Indexed: 10/21/2022]
Abstract
We examined expression of two plant genes encoding coclaurine N-methyltransferase (CMT) and norcoclaurine synthase (NCS) in Escherichia coli from the Salmonella entericaprpBCDE promoter (P(prpB)) and compared it to that from the strongest IPTG-inducible promoter, P(T7). In contrast to our previous study showing slightly higher production of green fluorescent protein (GFP) from the pPro system compared to that from the T7 system, production of two plant proteins CMT and NCS from P(prpB) was 2- to 4-fold higher than that from P(T7). Unlike P(T7), expression from P(prpB) did not reduce cell growth even when highly induced, indicating that this propionate-inducible system is more efficient for overproduction of proteins that result in growth inhibition. In an auto-induction experiment, which does not require monitoring the culture or adding inducer during cell growth, the pPro system exhibited much higher protein production than the T7 system. These results strongly indicate that the pPro system is well-suited for overproduction of recombinant proteins.
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Affiliation(s)
- Sung Kuk Lee
- Department of Chemical Engineering, University of California, Berkeley, CA 94720, USA.
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10
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Chang CW, Christensen LV, Lee M, Kim SW. Efficient expression of vascular endothelial growth factor using minicircle DNA for angiogenic gene therapy. J Control Release 2007; 125:155-63. [PMID: 18063165 DOI: 10.1016/j.jconrel.2007.10.014] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2007] [Revised: 10/05/2007] [Accepted: 10/17/2007] [Indexed: 10/22/2022]
Abstract
The application of plasmid DNA (pDNA)-based gene therapy is limited by its inefficient transgene expression. In this study, minicircle DNA was evaluated for efficient vascular endothelial growth factor (VEGF) expression in skeletal muscle cells. Production of minicircle DNA encoding VEGF was studied by a semi-quantitative electrophoresis method leading to optimized bacterial culture conditions and producing high purity (86.6%) minicircle DNA. The VEGF minicircle DNA under control of the SV40 promoter (pMini-SV-VEGF) showed an increased amount of VEGF mRNA and up to 8 times more VEGF expression than a conventional plasmid (pSV-VEGF) in two different skeletal muscle cell lines (C2C12 and L8). Minicircle DNA with different promoters, including the SV40, CMV and chicken beta-actin, was tested for VEGF expression in a C2C12 skeletal muscle cell line. The high VEGF expression generated by minicircle DNA stimulated efficient endothelial cell growth in vitro. Furthermore, minicircle DNA expressed higher VEGF compared to conventional plasmid in the tibialis anterior (TA) muscle of mice. Taken together, the results suggest that minicircle DNA is an efficacious gene vector for angiogenic VEGF expression in skeletal muscle and may be useful for treating peripheral arterial disease (PAD).
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Affiliation(s)
- Chien-Wen Chang
- Department of Pharmaceutics and Pharmaceutical Chemistry, University of Utah, Salt Lake City, UT 84112-5820, USA
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11
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Chou CP. Engineering cell physiology to enhance recombinant protein production in Escherichia coli. Appl Microbiol Biotechnol 2007; 76:521-32. [PMID: 17571257 DOI: 10.1007/s00253-007-1039-0] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2007] [Revised: 05/08/2007] [Accepted: 05/21/2007] [Indexed: 11/26/2022]
Abstract
The advent of recombinant DNA technology has revolutionized the strategies for protein production. Due to the well-characterized genome and a variety of mature tools available for genetic manipulation, Escherichia coli is still the most common workhorse for recombinant protein production. However, the culture for industrial applications often presents E. coli cells with a growth condition that is significantly different from their natural inhabiting environment in the gastrointestinal tract, resulting in deterioration in cell physiology and limitation in cell's productivity. It has been recognized that innovative design of genetically engineered strains can highly increase the bioprocess yield with minimum investment on the capital and operating costs. Nevertheless, most of these genetic manipulations, by which traits are implanted into the workhorse through recombinant DNA technology, for enhancing recombinant protein productivity often translate into the challenges that deteriorate cell physiology or even jeopardize cell survival. An in-depth understanding of these challenges and their corresponding cellular response at the molecular level becomes crucial for developing superior strains that are more physiologically adaptive to the production environment to improve culture productivity. With the accumulated knowledge in cell physiology, whose importance to gene overexpression was to some extent undervalued previously, this review is intended to focus on the recent biotechnological advancement in engineering cell physiology to enhance recombinant protein production in E. coli.
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Affiliation(s)
- C Perry Chou
- Department of Chemical Engineering, University of Waterloo, 200 University Avenue West, Waterloo, ON, Canada, N2L 3G1.
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12
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Mattanovich D, Borth N. Applications of cell sorting in biotechnology. Microb Cell Fact 2006; 5:12. [PMID: 16551353 PMCID: PMC1435767 DOI: 10.1186/1475-2859-5-12] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2005] [Accepted: 03/21/2006] [Indexed: 01/28/2023] Open
Abstract
Due to its unique capability to analyze a large number of single cells for several parameters simultaneously, flow cytometry has changed our understanding of the behavior of cells in culture and of the population dynamics even of clonal populations. The potential of this method for biotechnological research, which is based on populations of living cells, was soon appreciated. Sorting applications, however, are still less frequent than one would expect with regard to their potential. This review highlights important contributions where flow cytometric cell sorting was used for physiological research, protein engineering, cell engineering, specifically emphasizing selection of overproducing cell lines. Finally conclusions are drawn concerning the impact of cell sorting on inverse metabolic engineering and systems biology.
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Affiliation(s)
- Diethard Mattanovich
- University of Natural Resources and Applied Life Sciences Vienna, Department of Biotechnology, Institute of Applied Microbiology, Muthgasse 18, A-1190 Vienna, Austria
- School of Bioengineering, University of Applied Sciences FH-Campus Vienna, Muthgasse 18, A-1190 Vienna, Austria
| | - Nicole Borth
- University of Natural Resources and Applied Life Sciences Vienna, Department of Biotechnology, Institute of Applied Microbiology, Muthgasse 18, A-1190 Vienna, Austria
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Looser V, Hammes F, Keller M, Berney M, Kovar K, Egli T. Flow-cytometric detection of changes in the physiological state of E. coli expressing a heterologous membrane protein during carbon-limited fedbatch cultivation. Biotechnol Bioeng 2005; 92:69-78. [PMID: 16142799 DOI: 10.1002/bit.20575] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The key to optimizing productivity during industrial fermentations is the ability to rapidly monitor and interpret the physiological state of single microbial cells in a population and to recognize and characterize different sub-populations. Here, a flow cytometry-based method for the reproducible detection of changes in membrane function and/or structure of recombinant E. coli JM101 (pSPZ3) expressing xylene monooxygenase (XMO), was developed. XMO expression led to compromised but not permeabilized cell membranes. This was deduced from the fact that recombinant cells only stained with ethidium bromide (EB) and not with propidium iodide (PI). During the glucose-limited fedbatch cultivation, an increase from 25% to 95% of EB-stained cells was observed, occurring between 2 and 5 h after induction. Control experiments confirmed that this increase was due to the recombinant protein production and not caused by any possible effects of varying substrate availability, high cell density, plasmid replication or the presence of the inducing agent. We hypothesize that the integration of the recombinant protein into the cell membrane physically disrupted the functionality of the efflux pumps, thus resulting in EB-staining of the recombinant cells. This method enabled us to detect changes in the physiological state of single cells 2-4 h before other indications of partial cell damage, such as unbalanced growth, acetate accumulation and an increased CO(2) production rate, were observed. This method therefore shows promise with respect to the further development of an early-warning system to prevent sudden productivity decreases in processes with recombinant E. coli expressing heterologous membrane proteins.
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Affiliation(s)
- V Looser
- University of Applied Sciences Zürich (HSW ZFH), Grüental, CH-8820 Wädenswil, Switzerland
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14
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Sörensen M, Lippuner C, Kaiser T, Misslitz A, Aebischer T, Bumann D. Rapidly maturing red fluorescent protein variants with strongly enhanced brightness in bacteria. FEBS Lett 2003; 552:110-4. [PMID: 14527670 DOI: 10.1016/s0014-5793(03)00856-1] [Citation(s) in RCA: 84] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
A rapidly maturing variant of the red fluorescent protein DsRed was optimized for bacterial expression by random mutagenesis. The brightest variant contains six mutations, two of which (S4T and a silent mutation in codon 2) explain most of the fluorescence enhancement. The novel variants are expressed at 9-60-fold higher levels in Escherichia coli compared to DsRed.T3, but are not superior fluorophores on a per molecule basis. In contrast to previously available DsRed variants, DsRed.T3_S4T is sufficiently bright to monitor Salmonella gene expression in infected animals using flow cytometry. However, no fluorescence enhancement was observed in Leishmania or HeLa cells, indicating that these novel variants are specifically useful for bacteria.
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Affiliation(s)
- Meike Sörensen
- Department of Molecular Biology, Max-Planck-Institute for Infection Biology, Schumannstr. 21/22, D-10117 Berlin, Germany
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