1
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Toya Y, Shimizu H. Coupling and uncoupling growth and product formation for producing chemicals. Curr Opin Biotechnol 2024; 87:103133. [PMID: 38640846 DOI: 10.1016/j.copbio.2024.103133] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Revised: 03/31/2024] [Accepted: 04/01/2024] [Indexed: 04/21/2024]
Abstract
Microbial fermentation employs two strategies: growth- and nongrowth-coupled productions. Stoichiometric metabolic models with flux balance analysis enable pathway engineering to couple target synthesis with growth, yielding numerous successful results. Growth-coupled engineering also contributes to improving bottleneck flux through subsequent adaptive evolution. However, because growth-coupled production inevitably shares resources between biomass and target syntheses, the cost-effective production of bulk chemicals mandates a nongrowth-coupled approach. In such processes, understanding how and when to transition the metabolic state from growth to production modes becomes crucial, as does maintaining cellular activity during the nongrowing state to achieve high productivity. In this paper, we review recent technologies for growth-coupled and nongrowth-coupled production, considering their advantages and disadvantages.
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Affiliation(s)
- Yoshihiro Toya
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Hiroshi Shimizu
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka 565-0871, Japan.
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2
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Kulakowski S, Banerjee D, Scown CD, Mukhopadhyay A. Improving microbial bioproduction under low-oxygen conditions. Curr Opin Biotechnol 2023; 84:103016. [PMID: 37924688 DOI: 10.1016/j.copbio.2023.103016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 09/17/2023] [Accepted: 10/07/2023] [Indexed: 11/06/2023]
Abstract
Microbial bioconversion provides access to a wide range of sustainably produced chemicals and commodities. However, industrial-scale bioproduction process operations are preferred to be anaerobic due to the cost associated with oxygen transfer. Anaerobic bioconversion generally offers limited substrate utilization profiles, lower product yields, and reduced final product diversity compared with aerobic processes. Bioproduction under conditions of reduced oxygen can overcome the limitations of fully aerobic and anaerobic bioprocesses, but many microbial hosts are not developed for low-oxygen bioproduction. Here, we describe advances in microbial strain engineering involving the use of redox cofactor engineering, genome-scale metabolic modeling, and functional genomics to enable improved bioproduction processes under low oxygen and provide a viable path for scaling these bioproduction systems to industrial scales.
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Affiliation(s)
- Shawn Kulakowski
- Joint BioEnergy Institute, Emeryville, CA 94608, USA; Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Deepanwita Banerjee
- Joint BioEnergy Institute, Emeryville, CA 94608, USA; Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Corinne D Scown
- Joint BioEnergy Institute, Emeryville, CA 94608, USA; Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Energy Analysis and Environmental Impacts Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Aindrila Mukhopadhyay
- Joint BioEnergy Institute, Emeryville, CA 94608, USA; Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Environmental Genomics & Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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3
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Cordell WT, Avolio G, Takors R, Pfleger BF. Milligrams to kilograms: making microbes work at scale. Trends Biotechnol 2023; 41:1442-1457. [PMID: 37271589 DOI: 10.1016/j.tibtech.2023.05.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/08/2023] [Accepted: 05/09/2023] [Indexed: 06/06/2023]
Abstract
If biomanufacturing can become a sustainable route for producing chemicals, it will provide a critical step in reducing greenhouse gas emissions to fight climate change. However, efforts to industrialize microbial synthesis of chemicals have met with varied success, due, in part, to challenges in translating laboratory successes to industrial scale. With a particular focus on Escherichia coli, this review examines the lessons learned when studying microbial physiology and metabolism under conditions that simulate large-scale bioreactors and methods to minimize cellular waste through reduction of maintenance energy, optimizing the stress response and minimizing culture heterogeneity. With general strategies to overcome these challenges, biomanufacturing process scale-up could be de-risked and the time and cost of bringing promising syntheses to market could be reduced.
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Affiliation(s)
- William T Cordell
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Gennaro Avolio
- Institute of Biochemical Engineering, University of Stuttgart, Stuttgart 70569, Germany
| | - Ralf Takors
- Institute of Biochemical Engineering, University of Stuttgart, Stuttgart 70569, Germany
| | - Brian F Pfleger
- Department of Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, WI 53706, USA; DOE Center Advanced Bioenergy and Bioproducts Innovation, University of Wisconsin-Madison, Madison, WI 53706, USA; DOE Great Lakes Bioenergy Research Center, University of Wisconsin-Madison, Madison, WI 53706, USA.
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4
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Boecker S, Schulze P, Klamt S. Growth-coupled anaerobic production of isobutanol from glucose in minimal medium with Escherichia coli. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:148. [PMID: 37789464 PMCID: PMC10548627 DOI: 10.1186/s13068-023-02395-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 09/18/2023] [Indexed: 10/05/2023]
Abstract
BACKGROUND The microbial production of isobutanol holds promise to become a sustainable alternative to fossil-based synthesis routes for this important chemical. Escherichia coli has been considered as one production host, however, due to redox imbalance, growth-coupled anaerobic production of isobutanol from glucose in E. coli is only possible if complex media additives or small amounts of oxygen are provided. These strategies have a negative impact on product yield, productivity, reproducibility, and production costs. RESULTS In this study, we propose a strategy based on acetate as co-substrate for resolving the redox imbalance. We constructed the E. coli background strain SB001 (ΔldhA ΔfrdA ΔpflB) with blocked pathways from glucose to alternative fermentation products but with an enabled pathway for acetate uptake and subsequent conversion to ethanol via acetyl-CoA. This strain, if equipped with the isobutanol production plasmid pIBA4, showed robust exponential growth (µ = 0.05 h-1) under anaerobic conditions in minimal glucose medium supplemented with small amounts of acetate. In small-scale batch cultivations, the strain reached a glucose uptake rate of 4.8 mmol gDW-1 h-1, a titer of 74 mM and 89% of the theoretical maximal isobutanol/glucose yield, while secreting only small amounts of ethanol synthesized from acetate. Furthermore, we show that the strain keeps a high metabolic activity also in a pulsed fed-batch bioreactor cultivation, even if cell growth is impaired by the accumulation of isobutanol in the medium. CONCLUSIONS This study showcases the beneficial utilization of acetate as a co-substrate and redox sink to facilitate growth-coupled production of isobutanol under anaerobic conditions. This approach holds potential for other applications with different production hosts and/or substrate-product combinations.
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Affiliation(s)
- Simon Boecker
- Analysis and Redesign of Biological Networks, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106, Magdeburg, Germany
- University of Applied Sciences Berlin, Seestr. 64, 13347, Berlin, Germany
| | - Peter Schulze
- Physical and Chemical Foundations of Process Engineering, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106, Magdeburg, Germany
| | - Steffen Klamt
- Analysis and Redesign of Biological Networks, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106, Magdeburg, Germany.
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5
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Liu YX, Zhuo XZ, Li SY. The Transcription Activator AtxA from Bacillus Anthracis was Employed for Developing a Tight-Control, High-Level, Modulable, and Stationary-Phase Specific Transcription Activity in Escherichia Coli. Synth Biol (Oxf) 2022; 7:ysac014. [PMID: 36046151 PMCID: PMC9424709 DOI: 10.1093/synbio/ysac014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Revised: 06/16/2022] [Accepted: 08/16/2022] [Indexed: 11/13/2022] Open
Abstract
The strong transcriptional activity of the virulent gene pagA in Bacillus anthracis has been proven to be anthrax toxin activator (AtxA)-regulated. However, the obscure pagA transcription mechanism hinders practical applications of this strong promoter. In this study, a 509-bp DNA fragment [termed 509sequence, (−508)-(+1) relative to the P2 transcription start site] was cloned upstream of rbs-GFPuv as pTOL02B to elucidate the AtxA-regulated transcription. The 509sequence was dissected into the −10 sequence, −35 sequence, ATrich tract, SLI/SLII and upstream site. In conjunction with the heterologous co-expression of AtxA (under the control of the T7 promoter), the −10 sequence (TATACT) was sufficient for the AtxA-regulated transcription. Integration of pTOL02F + pTOLAtxA as pTOL03F showed that the AtxA-regulated transcription exhibited a strong specific fluorescence intensity/common analytical chemistry term (OD600) of 40 597 ± 446 and an induction/repression ratio of 122. An improved induction/repression ratio of 276 was achieved by cultivating Escherichia coli/pTOL03F in M9 minimal medium. The newly developed promoter system termed PAtxA consists of AtxA, the −10 sequence and Escherichia RNA polymerase. These three elements synergistically and cooperatively formed a previously undiscovered transcription system, which exhibited a tight-control, high-level, modulable and stationary-phase-specific transcription. The PAtxA was used for phaCAB expression for the stationary-phase polyhydroxybutyrate production, and the results showed that a PHB yield, content and titer of 0.20 ± 0.27 g/g-glucose, 68 ± 11% and 1.5 ± 0.4 g/l can be obtained. The positive inducible PAtxA, in contrast to negative inducible, should be a useful tool to diversify the gene information flow in synthetic biology.
Graphical Abstract
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Affiliation(s)
- Ying-Xing Liu
- Department of Chemical Engineering, National Chung Hsing University , Taichung 402, Taiwan
| | - Xiao-Zhen Zhuo
- Department of Chemical Engineering, National Chung Hsing University , Taichung 402, Taiwan
| | - Si-Yu Li
- Department of Chemical Engineering, National Chung Hsing University , Taichung 402, Taiwan
- Innovation and Development Center of Sustainable Agriculture, National Chung Hsing University , Taichung 402, Taiwan
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6
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Kasari M, Kasari V, Kärmas M, Jõers A. Decoupling Growth and Production by Removing the Origin of Replication from a Bacterial Chromosome. ACS Synth Biol 2022; 11:2610-2622. [PMID: 35798328 DOI: 10.1021/acssynbio.1c00618] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Efficient production of biochemicals and proteins in cell factories frequently benefits from a two-stage bioprocess in which growth and production phases are decoupled. Here, we describe a novel growth switch based on the permanent removal of the origin of replication (oriC) from the Escherichia coli chromosome. Without oriC, cells cannot initiate a new round of replication, and they stop growing while their metabolism remains active. Our system relies on a serine recombinase from bacteriophage phiC31 whose expression is controlled by the temperature-sensitive cI857 repressor from phage lambda. The reporter protein expression in switched cells continues after cessation of growth, leading to protein levels up to 5 times higher compared to nonswitching cells. Switching induces a unique physiological state that is different from both normal exponential and stationary phases. The switched cells remain in this state even when not growing, retain their protein synthesis capacity, and do not induce proteins associated with the stationary phase. Our switcher technology is potentially useful for a range of products and applicable in many bacterial species for decoupling growth and production.
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Affiliation(s)
- Marje Kasari
- Institute of Technology, University of Tartu, Nooruse 1, 50104 Tartu, Estonia
| | - Villu Kasari
- Institute of Technology, University of Tartu, Nooruse 1, 50104 Tartu, Estonia
| | - Mirjam Kärmas
- Institute of Technology, University of Tartu, Nooruse 1, 50104 Tartu, Estonia
| | - Arvi Jõers
- Institute of Technology, University of Tartu, Nooruse 1, 50104 Tartu, Estonia
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7
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Impact of Elevated Levels of Dissolved CO2 on Performance and Proteome Response of an Industrial 2′-Fucosyllactose Producing Escherichia coli Strain. Microorganisms 2022; 10:microorganisms10061145. [PMID: 35744663 PMCID: PMC9228177 DOI: 10.3390/microorganisms10061145] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/17/2022] [Accepted: 05/24/2022] [Indexed: 11/23/2022] Open
Abstract
Large-scale microbial industrial fermentations have significantly higher absolute pressure and dissolved CO2 concentrations than otherwise comparable laboratory-scale processes. Yet the effect of increased dissolved CO2 (dCO2) levels is rarely addressed in the literature. In the current work, we have investigated the impact of industrial levels of dCO2 (measured as the partial pressure of CO2, pCO2) in an Escherichia coli-based fed-batch process producing the human milk oligosaccharide 2′-fucosyllactose (2′-FL). The study evaluated the effect of high pCO2 levels in both carbon-limited (C-limited) and carbon/nitrogen-limited (C/N-limited) fed-batch processes. High-cell density cultures were sparged with 10%, 15%, 20%, or 30% CO2 in the inlet air to cover and exceed the levels observed in the industrial scale process. While the 10% enrichment was estimated to achieve similar or higher pCO2 levels as the large-scale fermentation it did not impact the performance of the process. The product and biomass yields started being affected above 15% CO2 enrichment, while 30% impaired the cultures completely. Quantitative proteomics analysis of the C-limited process showed that 15% CO2 enrichment affected the culture on the protein level, but to a much smaller degree than expected. A more significant impact was seen in the dual C/N limited process, which likely stemmed from the effect pCO2 had on nitrogen availability. The results demonstrated that microbial cultures can be seriously affected by elevated CO2 levels, albeit at higher levels than expected.
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8
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Glover G, Voliotis M, Łapińska U, Invergo BM, Soanes D, O'Neill P, Moore K, Nikolic N, Petrov PG, Milner DS, Roy S, Heesom K, Richards TA, Tsaneva-Atanasova K, Pagliara S. Nutrient and salt depletion synergistically boosts glucose metabolism in individual Escherichia coli cells. Commun Biol 2022; 5:385. [PMID: 35444215 PMCID: PMC9021252 DOI: 10.1038/s42003-022-03336-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 03/30/2022] [Indexed: 12/16/2022] Open
Abstract
The interaction between a cell and its environment shapes fundamental intracellular processes such as cellular metabolism. In most cases growth rate is treated as a proximal metric for understanding the cellular metabolic status. However, changes in growth rate might not reflect metabolic variations in individuals responding to environmental fluctuations. Here we use single-cell microfluidics-microscopy combined with transcriptomics, proteomics and mathematical modelling to quantify the accumulation of glucose within Escherichia coli cells. In contrast to the current consensus, we reveal that environmental conditions which are comparatively unfavourable for growth, where both nutrients and salinity are depleted, increase glucose accumulation rates in individual bacteria and population subsets. We find that these changes in metabolic function are underpinned by variations at the translational and posttranslational level but not at the transcriptional level and are not dictated by changes in cell size. The metabolic response-characteristics identified greatly advance our fundamental understanding of the interactions between bacteria and their environment and have important ramifications when investigating cellular processes where salinity plays an important role.
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Affiliation(s)
- Georgina Glover
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK
| | - Margaritis Voliotis
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Department of Mathematics, University of Exeter, Stocker Road, Exeter, UK
| | - Urszula Łapińska
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Brandon M Invergo
- Translational Research Exchange at Exeter, University of Exeter, Exeter, UK
| | - Darren Soanes
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Paul O'Neill
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Karen Moore
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Nela Nikolic
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - Peter G Petrov
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK
| | - David S Milner
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford, OX1 3SZ, UK
| | - Sumita Roy
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Kate Heesom
- University of Bristol Proteomics Facility, University Walk, Bristol, BS8 1TD, UK
| | - Thomas A Richards
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford, OX1 3SZ, UK
| | - Krasimira Tsaneva-Atanasova
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Department of Mathematics, University of Exeter, Stocker Road, Exeter, UK
- Department of Bioinformatics and Mathematical Modelling, Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 105 Acad. G. Bonchev Str., 1113, Sofia, Bulgaria
| | - Stefano Pagliara
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK.
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9
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Ziegler M, Hägele L, Gäbele T, Takors R. CRISPRi enables fast growth followed by stable aerobic pyruvate formation in
Escherichia coli
without auxotrophy. Eng Life Sci 2021; 22:70-84. [PMID: 35140555 PMCID: PMC8811725 DOI: 10.1002/elsc.202100021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 10/06/2021] [Accepted: 11/10/2021] [Indexed: 11/13/2022] Open
Abstract
CRISPR interference (CRISPRi) was applied to enable the aerobic production of pyruvate in Escherichia coli MG1655 under glucose excess conditions by targeting the promoter regions of aceE or pdhR. Knockdown strains were cultivated in aerobic shaking flasks and the influence of inducer concentration and different sgRNA binding sites on the production of pyruvate was measured. Targeting the promoter regions of aceE or pdhR triggered pyruvate production during the exponential phase and reduced expression of aceE. In lab‐scale bioreactor fermentations, an aceE silenced strain successfully produced pyruvate under fully aerobic conditions during the exponential phase, but loss of productivity occurred during a subsequent nitrogen‐limited phase. Targeting the promoter region of pdhR enabled pyruvate production during the growth phase of cultivations, and a continued low‐level accumulation during the nitrogen‐limited production phase. Combinatorial targeting of the promoter regions of both aceE and pdhR in E. coli MG1655 pdCas9 psgRNA_aceE_234_pdhR_329 resulted in the stable aerobic production of pyruvate with non‐growing cells at YP/S = 0.36 ± 0.029 gPyruvate/gGlucose in lab‐scale bioreactors throughout an extended nitrogen‐limited production phase.
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Affiliation(s)
- Martin Ziegler
- Institute of Biochemical Engineering University of Stuttgart Stuttgart Germany
| | - Lorena Hägele
- Institute of Biochemical Engineering University of Stuttgart Stuttgart Germany
| | - Teresa Gäbele
- Institute of Biochemical Engineering University of Stuttgart Stuttgart Germany
| | - Ralf Takors
- Institute of Biochemical Engineering University of Stuttgart Stuttgart Germany
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10
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Akinyemi TS, Shao N, Lyu Z, Drake IJ, Liu Y, Whitman WB. Tuning Gene Expression by Phosphate in the Methanogenic Archaeon Methanococcus maripaludis. ACS Synth Biol 2021; 10:3028-3039. [PMID: 34665610 DOI: 10.1021/acssynbio.1c00322] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Methanococcus maripaludis is a rapidly growing, hydrogenotrophic, and genetically tractable methanogen with unique capabilities to convert formate and CO2 to CH4. The existence of genome-scale metabolic models and an established, robust system for both large-scale and continuous cultivation make it amenable for industrial applications. However, the lack of molecular tools for differential gene expression has hindered its application as a microbial cell factory to produce biocatalysts and biochemicals. In this study, a library of differentially regulated promoters was designed and characterized based on the pst promoter, which responds to the inorganic phosphate concentration in the growth medium. Gene expression increases by 4- to 6-fold when the medium phosphate drops to growth-limiting concentrations. Hence, this regulated system decouples growth from heterologous gene expression without the need for adding an inducer. The minimal pst promoter is identified and contains a conserved AT-rich region, a factor B recognition element, and a TATA box for phosphate-dependent regulation. Rational changes to the factor B recognition element and start codon had no significant impact on expression; however, changes to the transcription start site and the 5' untranslated region resulted in the differential protein production with regulation remaining intact. Compared to a previous expression system based upon the histone promoter, this regulated expression system resulted in significant improvements in the expression of a key methanogenic enzyme complex, methyl-coenzyme M reductase, and the potentially toxic arginine methyltransferase MmpX.
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Affiliation(s)
- Taiwo S. Akinyemi
- Department of Microbiology, University of Georgia, Athens, Georgia 30602, United States
| | - Nana Shao
- Department of Microbiology, University of Georgia, Athens, Georgia 30602, United States
| | - Zhe Lyu
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, United States
| | - Ian J. Drake
- Corporate Strategic Research, ExxonMobil Research & Engineering Company, Annandale, New Jersey 08801, United States
| | - Yuchen Liu
- Corporate Strategic Research, ExxonMobil Research & Engineering Company, Annandale, New Jersey 08801, United States
| | - William B. Whitman
- Department of Microbiology, University of Georgia, Athens, Georgia 30602, United States
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11
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Nair A, Sarma SJ. The impact of carbon and nitrogen catabolite repression in microorganisms. Microbiol Res 2021; 251:126831. [PMID: 34325194 DOI: 10.1016/j.micres.2021.126831] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Revised: 07/15/2021] [Accepted: 07/21/2021] [Indexed: 02/06/2023]
Abstract
Organisms have cellular machinery that is focused on optimum utilization of resources to maximize growth and survival depending on various environmental and developmental factors. Catabolite repression is a strategy utilized by various species of bacteria and fungi to accommodate changes in the environment such as the depletion of resources, or an abundance of less-favored nutrient sources. Catabolite repression allows for the rapid use of certain substrates like glucose over other carbon sources. Effective handling of carbon and nitrogen catabolite repression in microorganisms is crucial to outcompete others in nutrient limiting conditions. Investigations into genes and proteins linked to preferential uptake of different nutrients under various environmental conditions can aid in identifying regulatory mechanisms that are crucial for optimum growth and survival of microorganisms. The exact time and way bacteria and fungi switch their utilization of certain nutrients is of great interest for scientific, industrial, and clinical reasons. Catabolite repression is of great significance for industrial applications that rely on microorganisms for the generation of valuable bio-products. The impact catabolite repression has on virulence of pathogenic bacteria and fungi and disease progression in hosts makes it important area of interest in medical research for the prevention of diseases and developing new treatment strategies. Regulatory networks under catabolite repression exemplify the flexibility and the tremendous diversity that is found in microorganisms and provides an impetus for newer insights into these networks.
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Affiliation(s)
- Abhinav Nair
- Department of Biotechnology, School of Engineering and Applied Sciences, Bennett University, Greater Noida, Uttar Pradesh, India
| | - Saurabh Jyoti Sarma
- Department of Biotechnology, School of Engineering and Applied Sciences, Bennett University, Greater Noida, Uttar Pradesh, India.
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12
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Structure elucidation of the elusive Enzyme I monomer reveals the molecular mechanisms linking oligomerization and enzymatic activity. Proc Natl Acad Sci U S A 2021; 118:2100298118. [PMID: 33975952 DOI: 10.1073/pnas.2100298118] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Enzyme I (EI) is a phosphotransferase enzyme responsible for converting phosphoenolpyruvate (PEP) into pyruvate. This reaction initiates a five-step phosphorylation cascade in the bacterial phosphotransferase (PTS) transduction pathway. Under physiological conditions, EI exists in an equilibrium between a functional dimer and an inactive monomer. The monomer-dimer equilibrium is a crucial factor regulating EI activity and the phosphorylation state of the overall PTS. Experimental studies of EI's monomeric state have yet been hampered by the dimer's high thermodynamic stability, which prevents its characterization by standard structural techniques. In this study, we modified the dimerization domain of EI (EIC) by mutating three amino acids involved in the formation of intersubunit salt bridges. The engineered variant forms an active dimer in solution that can bind and hydrolyze PEP. Using hydrostatic pressure as an additional perturbation, we were then able to study the complete dissociation of the variant from 1 bar to 2.5 kbar in the absence and the presence of EI natural ligands. Backbone residual dipolar couplings collected under high-pressure conditions allowed us to determine the conformational ensemble of the isolated EIC monomeric state in solution. Our calculations reveal that three catalytic loops near the dimerization interface become unstructured upon monomerization, preventing the monomeric enzyme from binding its natural substrate. This study provides an atomic-level characterization of EI's monomeric state and highlights the role of the catalytic loops as allosteric connectors controlling both the activity and oligomerization of the enzyme.
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13
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Ziegler M, Zieringer J, Takors R. Transcriptional profiling of the stringent response mutant strain E. coli SR reveals enhanced robustness to large-scale conditions. Microb Biotechnol 2021; 14:993-1010. [PMID: 33369128 PMCID: PMC8085953 DOI: 10.1111/1751-7915.13738] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 12/08/2020] [Accepted: 12/08/2020] [Indexed: 12/05/2022] Open
Abstract
In large-scale fed-batch production processes, microbes are exposed to heterogeneous substrate availability caused by long mixing times. Escherichia coli, the most common industrial host for recombinant protein production, reacts by recurring accumulation of the alarmone ppGpp and energetically wasteful transcriptional strategies. Here, we compare the regulatory responses of the stringent response mutant strain E. coli SR and its parent strain E. coli MG1655 to repeated nutrient starvation in a two-compartment scale-down reactor. Our data show that E. coli SR can withstand these stress conditions without a ppGpp-mediated stress response maintaining fully functional ammonium uptake and biomass formation. Furthermore, E. coli SR exhibited a substantially reduced short-term transcriptional response compared to E. coli MG1655 (less than half as many differentially expressed genes). E. coli SR proceeded adaptation via more general SOS response pathways by initiating negative regulation of transcription, translation and cell division. Our results show that locally induced stress responses propagating through the bioreactor do not result in cyclical induction and repression of genes in E. coli SR, but in a reduced and coordinated response, which makes it potentially suitable for large-scale production processes.
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Affiliation(s)
- Martin Ziegler
- Institute of Biochemical EngineeringUniversity of StuttgartStuttgartGermany
| | - Julia Zieringer
- Institute of Biochemical EngineeringUniversity of StuttgartStuttgartGermany
| | - Ralf Takors
- Institute of Biochemical EngineeringUniversity of StuttgartStuttgartGermany
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Di Caprio F. A fattening factor to quantify the accumulation ability of microorganisms under N-starvation. N Biotechnol 2021; 66:70-78. [PMID: 33862285 DOI: 10.1016/j.nbt.2021.04.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 04/06/2021] [Accepted: 04/10/2021] [Indexed: 01/04/2023]
Abstract
Many microorganisms can accumulate biomass in the form of lipids and polysaccharides, which can be used for biofuels, bioplastics, food and feed. Some innovative bioprocesses exploit the competitive advantage provided by such accumulation ability, mainly under N-starvation, to select high-accumulating strains against biological contaminants, by using uncoupled nutrient feeding. However, there is no general and easily comparable parameter available to compare biomass accumulation ability among different microbial strains, which could measure the competitive advantage. Here, a parameter termed "fattening factor" (ηx) is described to quantify such strain-specific biomass accumulation ability in bacteria, yeasts and microalgae. This parameter measures how many fold a microbial population can increase its biomass just as the result of accumulation. It is derived from considerations about the main metabolic aspects of cells' response to N-starvation, which induces variations in cell cycle, biomass production and biochemical composition. The fattening factor described here should be easily estimatable in N-starvation for every culturable microbial strain, by measuring the amount of accumulated biomass.
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Affiliation(s)
- Fabrizio Di Caprio
- Department of Chemistry, University Sapienza of Rome, Piazzale Aldo Moro 5, 00185, Rome, Italy.
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15
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Di Caprio F. Cultivation processes to select microorganisms with high accumulation ability. Biotechnol Adv 2021; 49:107740. [PMID: 33838283 DOI: 10.1016/j.biotechadv.2021.107740] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2020] [Revised: 02/26/2021] [Accepted: 03/26/2021] [Indexed: 10/21/2022]
Abstract
The microbial ability to accumulate biomolecules is fundamental for different biotechnological applications aiming at the production of biofuels, food and bioplastics. However, high accumulation is a selective advantage only under certain stressful conditions, such as nutrient depletion, characterized by lower growth rate. Conventional bioprocesses maintain an optimal and stable environment for large part of the cultivation, that doesn't reward cells for their accumulation ability, raising the risk of selection of contaminant strains with higher growth rate, but lower accumulation of products. Here in this work the physiological responses of different microorganisms (microalgae, bacteria, yeasts) under N-starvation and energy starvation are reviewed, with the aim to furnish relevant insights exploitable to develop tailored bioprocesses to select specific strains for their higher accumulation ability. Microorganism responses to starvation are reviewed focusing on cell cycle, biomass production and variations in biochemical composition. Then, the work describes different innovative bioprocess configurations exploiting uncoupled nutrient feeding strategies (feast-famine), tailored to maintain a selective pressure to reward the strains with higher accumulation ability in mixed microbial populations. Finally, the main models developed in recent studies to describe and predict microbial growth and intracellular accumulation upon N-starvation and feast-famine conditions have been reviewed.
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Affiliation(s)
- Fabrizio Di Caprio
- Department of Chemistry, University Sapienza of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy.
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16
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Boecker S, Harder BJ, Kutscha R, Pflügl S, Klamt S. Increasing ATP turnover boosts productivity of 2,3-butanediol synthesis in Escherichia coli. Microb Cell Fact 2021; 20:63. [PMID: 33750397 PMCID: PMC7941745 DOI: 10.1186/s12934-021-01554-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 02/25/2021] [Indexed: 12/23/2022] Open
Abstract
Background The alcohol 2,3-butanediol (2,3-BDO) is an important chemical and an Escherichia coli producer strain was recently engineered for bio-based production of 2,3-BDO. However, further improvements are required for realistic applications. Results Here we report that enforced ATP wasting, implemented by overexpressing the genes of the ATP-hydrolyzing F1-part of the ATPase, leads to significant increases of yield and especially of productivity of 2,3-BDO synthesis in an E. coli producer strain under various cultivation conditions. We studied aerobic and microaerobic conditions as well as growth-coupled and growth-decoupled production scenarios. In all these cases, the specific substrate uptake and 2,3-BDO synthesis rate (up to sixfold and tenfold higher, respectively) were markedly improved in the ATPase strain compared to a control strain. However, aerobic conditions generally enable higher productivities only with reduced 2,3-BDO yields while high product yields under microaerobic conditions are accompanied with low productivities. Based on these findings we finally designed and validated a three-stage process for optimal conversion of glucose to 2,3-BDO, which enables a high productivity in combination with relatively high yield. The ATPase strain showed again superior performance and finished the process twice as fast as the control strain and with higher 2,3-BDO yield. Conclusions Our results demonstrate the high potential of enforced ATP wasting as a generic metabolic engineering strategy and we expect more applications to come in the future. Supplementary Information The online version contains supplementary material available at 10.1186/s12934-021-01554-x.
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Affiliation(s)
- Simon Boecker
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany
| | - Björn-Johannes Harder
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany
| | - Regina Kutscha
- Institute for Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060, Vienna, Austria
| | - Stefan Pflügl
- Institute for Chemical, Environmental and Bioscience Engineering, Research Area Biochemical Engineering, Technische Universität Wien, Gumpendorfer Straße 1a, 1060, Vienna, Austria
| | - Steffen Klamt
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106, Magdeburg, Germany.
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17
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Riley LA, Guss AM. Approaches to genetic tool development for rapid domestication of non-model microorganisms. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:30. [PMID: 33494801 PMCID: PMC7830746 DOI: 10.1186/s13068-020-01872-z] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 12/30/2020] [Indexed: 05/04/2023]
Abstract
Non-model microorganisms often possess complex phenotypes that could be important for the future of biofuel and chemical production. They have received significant interest the last several years, but advancement is still slow due to the lack of a robust genetic toolbox in most organisms. Typically, "domestication" of a new non-model microorganism has been done on an ad hoc basis, and historically, it can take years to develop transformation and basic genetic tools. Here, we review the barriers and solutions to rapid development of genetic transformation tools in new hosts, with a major focus on Restriction-Modification systems, which are a well-known and significant barrier to efficient transformation. We further explore the tools and approaches used for efficient gene deletion, DNA insertion, and heterologous gene expression. Finally, more advanced and high-throughput tools are now being developed in diverse non-model microbes, paving the way for rapid and multiplexed genome engineering for biotechnology.
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Affiliation(s)
- Lauren A Riley
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA
- Bredesen Center, University of Tennessee, Knoxville, TN, 37996, USA
| | - Adam M Guss
- Biosciences Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
- Bredesen Center, University of Tennessee, Knoxville, TN, 37996, USA.
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18
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Krishnan A, McNeil BA, Stuart DT. Biosynthesis of Fatty Alcohols in Engineered Microbial Cell Factories: Advances and Limitations. Front Bioeng Biotechnol 2020; 8:610936. [PMID: 33344437 PMCID: PMC7744569 DOI: 10.3389/fbioe.2020.610936] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 11/10/2020] [Indexed: 11/19/2022] Open
Abstract
Concerns about climate change and environmental destruction have led to interest in technologies that can replace fossil fuels and petrochemicals with compounds derived from sustainable sources that have lower environmental impact. Fatty alcohols produced by chemical synthesis from ethylene or by chemical conversion of plant oils have a large range of industrial applications. These chemicals can be synthesized through biological routes but their free forms are produced in trace amounts naturally. This review focuses on how genetic engineering of endogenous fatty acid metabolism and heterologous expression of fatty alcohol producing enzymes have come together resulting in the current state of the field for production of fatty alcohols by microbial cell factories. We provide an overview of endogenous fatty acid synthesis, enzymatic methods of conversion to fatty alcohols and review the research to date on microbial fatty alcohol production. The primary focus is on work performed in the model microorganisms, Escherichia coli and Saccharomyces cerevisiae but advances made with cyanobacteria and oleaginous yeasts are also considered. The limitations to production of fatty alcohols by microbial cell factories are detailed along with consideration to potential research directions that may aid in achieving viable commercial scale production of fatty alcohols from renewable feedstock.
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Affiliation(s)
- Anagha Krishnan
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - Bonnie A McNeil
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
| | - David T Stuart
- Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
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19
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Aguilar F, Ekramzadeh K, Scheper T, Beutel S. Whole-Cell Production of Patchouli Oil Sesquiterpenes in Escherichia coli: Metabolic Engineering and Fermentation Optimization in Solid-Liquid Phase Partitioning Cultivation. ACS OMEGA 2020; 5:32436-32446. [PMID: 33376881 PMCID: PMC7758989 DOI: 10.1021/acsomega.0c04590] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 11/25/2020] [Indexed: 05/27/2023]
Abstract
Patchouli oil is a major ingredient in perfumery, granting a dark-woody scent due to its main constituent (-)-patchoulol. The growing demand for patchouli oil has raised interest in the development of a biotechnological process to assure a reliable supply. Herein, we report the production of patchouli oil sesquiterpenes by metabolically engineered Escherichia coli strains, using solid-liquid phase partitioning cultivation. The (-)-patchoulol production was possible using the endogenous methylerythritol phosphate pathway and overexpressing a (-)-patchoulol synthase isoform from Pogostemon cablin but at low titers. To improve the (-)-patchoulol production, the exogenous mevalonate pathway was overexpressed in the multi-plasmid PTS + Mev strain, which increased the (-)-patchoulol titer 5-fold. Fermentation was improved further by evaluating several defined media, and optimizing the pH and temperature of culture broth, enhancing the (-)-patchoulol titer 3-fold. To augment the (-)-patchoulol recovery from fermentation, the solid-liquid phase partitioning cultivation was analyzed by screening polymeric adsorbers, where the Diaion HP20 adsorber demonstrated the highest (-)-patchoulol recovery from all tests. Fermentation was scaled-up to fed-batch bioreactors, reaching a (-)-patchoulol titer of 40.2 mg L-1 and productivity of 20.1 mg L-1 d-1. The terpene profile and aroma produced from the PTS + Mev strain were similar to the patchouli oil, comprising (-)-patchoulol as the main product, and α-bulnesene, trans-β-caryophyllene, β-patchoulene, and guaia-5,11-diene as side products. This investigation represents the first study of (-)-patchoulol production in E. coli by solid-liquid phase partitioning cultivation, which provides new insights for the development of sustainable bioprocesses for the microbial production of fragrant terpenes.
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Affiliation(s)
- Francisco Aguilar
- Institute of Technical Chemistry, Leibniz University of Hannover, Callinstr. 5, 30167 Hannover, Germany
| | - Kimia Ekramzadeh
- Institute of Technical Chemistry, Leibniz University of Hannover, Callinstr. 5, 30167 Hannover, Germany
| | - Thomas Scheper
- Institute of Technical Chemistry, Leibniz University of Hannover, Callinstr. 5, 30167 Hannover, Germany
| | - Sascha Beutel
- Institute of Technical Chemistry, Leibniz University of Hannover, Callinstr. 5, 30167 Hannover, Germany
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20
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Ortega-Quintana FA, Trujillo-Roldán MA, Botero-Castro H, Alvarez H. Modeling the interaction between the central carbon metabolism of Escherichia coli and bioreactor culture media. Biochem Eng J 2020. [DOI: 10.1016/j.bej.2020.107753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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21
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Raj K, Venayak N, Mahadevan R. Novel two-stage processes for optimal chemical production in microbes. Metab Eng 2020; 62:186-197. [DOI: 10.1016/j.ymben.2020.08.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/24/2020] [Accepted: 08/07/2020] [Indexed: 12/27/2022]
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22
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Dynamic resource allocation drives growth under nitrogen starvation in eukaryotes. NPJ Syst Biol Appl 2020; 6:14. [PMID: 32415097 PMCID: PMC7229059 DOI: 10.1038/s41540-020-0135-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 04/16/2020] [Indexed: 12/18/2022] Open
Abstract
Cells can sense changes in their extracellular environment and subsequently adapt their biomass composition. Nutrient abundance defines the capability of the cell to produce biomass components. Under nutrient-limited conditions, resource allocation dramatically shifts to carbon-rich molecules. Here, we used dynamic biomass composition data to predict changes in growth and reaction flux distributions using the available genome-scale metabolic models of five eukaryotic organisms (three heterotrophs and two phototrophs). We identified temporal profiles of metabolic fluxes that indicate long-term trends in pathway and organelle function in response to nitrogen depletion. Surprisingly, our calculations of model sensitivity and biosynthetic cost showed that free energy of biomass metabolites is the main driver of biosynthetic cost and not molecular weight, thus explaining the high costs of arginine and histidine. We demonstrated how metabolic models can accurately predict the complexity of interwoven mechanisms in response to stress over the course of growth.
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23
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Heo W, Kim JH, Kim S, Kim KH, Kim HJ, Seo JH. Enhanced production of 3-hydroxypropionic acid from glucose and xylose by alleviation of metabolic congestion due to glycerol flux in engineered Escherichia coli. BIORESOURCE TECHNOLOGY 2019; 285:121320. [PMID: 30978585 DOI: 10.1016/j.biortech.2019.121320] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 04/02/2019] [Accepted: 04/03/2019] [Indexed: 06/09/2023]
Abstract
Among platform chemicals obtained from renewable biomass, 3-hydroxypropionic acid (3-HP) has attracted considerable attention. A GC/TOF-MS study revealed that the intracellular metabolites of the TCA cycle and fatty acid synthesis increased in JHS01302, a galP-overexpressing strain of Escherichia coli, during glucose and xylose co-fermentation. Decreased intracellular glycerol levels and increased intracellular biosynthesis of 3-HP were also detected in the strain. Based on these results, the yeast GPD1 gene was replaced with the endogenous gpsA gene to modulate the rate of glycerol metabolism. In flask cultures, JHS01304 containing the gpsA gene displayed 43% lower glycerol accumulation and 52% higher 3-HP production than the control. JHS01304 produced 37.6 g/L 3-HP with a productivity rate of 0.63 g/L/h and yield of 0.17 g/g in the fed-batch fermentation. The metabolome analysis provided valuable information for alleviating the metabolic burden of glycerol flux to improve the production of 3-HP during glucose and xylose co-fermentation.
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Affiliation(s)
- Woong Heo
- Department of Agricultural Biotechnology and Center for Food and Bioconvergence, Seoul National University, Seoul 08826, Republic of Korea
| | - Jun Hee Kim
- Interdisciplinary Program of Bioengineering, Seoul National University, Seoul 08826, Republic of Korea
| | - Sooah Kim
- Department of Biotechnology, Graduate School, Korea University, Seoul 02841, Republic of Korea
| | - Kyong Heon Kim
- Department of Biotechnology, Graduate School, Korea University, Seoul 02841, Republic of Korea
| | - Hyo Jin Kim
- Graduate School of International Agricultural Technology, Seoul National University, Pyeongchang 25354, Republic of Korea; Institutes of Green Bio Science and Technology, Seoul National University, Pyeongchang 25354, Republic of Korea.
| | - Jin-Ho Seo
- Department of Agricultural Biotechnology and Center for Food and Bioconvergence, Seoul National University, Seoul 08826, Republic of Korea; Interdisciplinary Program of Bioengineering, Seoul National University, Seoul 08826, Republic of Korea.
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24
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Kamiura R, Toya Y, Matsuda F, Shimizu H. Theophylline-inducible riboswitch accurately regulates protein expression at low level in Escherichia coli. Biotechnol Lett 2019; 41:743-751. [PMID: 30953309 DOI: 10.1007/s10529-019-02672-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2018] [Accepted: 03/31/2019] [Indexed: 12/11/2022]
Abstract
OBJECTIVES Fine-tuning of enzyme expression at low levels is an important challenge for metabolic engineers. Here, theophylline-inducible riboswitch for translational regulation was evaluated. The background expression, translation rate, and time delay for its induction was reported. RESULTS To evaluate the effect of the amount of mRNA on its translation rate, transcription of the riboswitch RNA with red fluorescent protein (RFP) was controlled by the lac system with addition of isopropyl β-D-1-thiogalactopyranoside in Escherichia coli. Regardless of the amount of riboswitch mRNA, the translation of RFP was completely suppressed without theophylline during both growth and stationary phases. Furthermore, a strong positive correlation between theophylline concentration (0 to 1 mM) and specific RFP production rate was observed. The specific RFP production rate with the riboswitch was approximately 2.3% of that without the riboswitch. Furthermore, 60 min of time delay for RFP expression was observed after adding theophylline during the stationary phase. CONCLUSION Theophylline-inducible riboswitch precisely controls protein translation at low expression levels with significantly low background expression. It can emerge as a powerful tool for fine tuning of enzyme expression.
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Affiliation(s)
- Rikuto Kamiura
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yoshihiro Toya
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan.
| | - Fumio Matsuda
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Hiroshi Shimizu
- Department of Bioinformatic Engineering, Graduate School of Information Science and Technology, Osaka University, 1-5 Yamadaoka, Suita, Osaka, 565-0871, Japan.
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25
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Modulating the Precursor and Terpene Synthase Supply for the Whole-Cell Biocatalytic Production of the Sesquiterpene (+)-Zizaene in a Pathway Engineered E. coli. Genes (Basel) 2019; 10:genes10060478. [PMID: 31238595 PMCID: PMC6627501 DOI: 10.3390/genes10060478] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2019] [Revised: 06/15/2019] [Accepted: 06/20/2019] [Indexed: 11/23/2022] Open
Abstract
The vetiver essential oil from Chrysopogon zizanioides contains fragrant sesquiterpenes used widely in the formulation of nearly 20% of men’s cosmetics. The growing demand and issues in the supply have raised interest in the microbial production of the sesquiterpene khusimol, the main compound of the vetiver essential oil due to its woody smell. In this study, we engineered the biosynthetic pathway for the production of (+)-zizaene, the immediate precursor of khusimol. A systematic approach of metabolic engineering in Escherichia coli was applied to modulate the critical bottlenecks of the metabolic flux towards (+)-zizaene. Initially, production of (+)-zizaene was possible with the endogenous methylerythritol phosphate pathway and the codon-optimized zizaene synthase (ZS). Raising the precursor E,E-farnesyl diphosphate supply through the mevalonate pathway improved the (+)-zizaene titers 2.7-fold, although a limitation of the ZS supply was observed. To increase the ZS supply, distinct promoters were tested for the expression of the ZS gene, which augmented 7.2-fold in the (+)-zizaene titers. Final metabolic enhancement for the ZS supply by using a multi-plasmid strain harboring multiple copies of the ZS gene improved the (+)-zizaene titers 1.3-fold. The optimization of the fermentation conditions increased the (+)-zizaene titers 2.2-fold, achieving the highest (+)-zizaene titer of 25.09 mg L−1. This study provides an alternative strategy to enhance the terpene synthase supply for the engineering of isoprenoids. Moreover, it demonstrates the development of a novel microbial platform for the sustainable production of fragrant molecules for the cosmetic industry.
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26
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Boecker S, Zahoor A, Schramm T, Link H, Klamt S. Broadening the Scope of Enforced ATP Wasting as a Tool for Metabolic Engineering in Escherichia coli. Biotechnol J 2019; 14:e1800438. [PMID: 30927494 DOI: 10.1002/biot.201800438] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 02/25/2019] [Indexed: 01/21/2023]
Abstract
The targeted increase of cellular adenosine triphosphate (ATP) turnover (enforced ATP wasting) has recently been recognized as a promising tool for metabolic engineering when product synthesis is coupled with net ATP formation. The goal of the present study is to further examine and to further develop the concept of enforced ATP wasting and to broaden its scope for potential applications. In particular, considering the fermentation products synthesized by Escherichia coli under anaerobic conditions as a proxy for target chemical(s), i) a new genetic module for dynamic and gradual induction of the F1 -part of the ATPase is developed and it is found that ii) induction of the ATPase leads to higher metabolic activity and increased product formation in E. coli under anaerobic conditions, and that iii) ATP wasting significantly increases substrate uptake and productivity of growth-arrested cells, which is vital for its use in two-stage processes. To the best of the authors' knowledge, the glucose uptake rate of 6.49 mmol gCDW-1 h-1 achieved with enforced ATP wasting is the highest value reported for nongrowing E. coli cells. In summary, this study shows that enforced ATP wasting can be used to improve yield and titer (in growth-coupled processes) as well as volumetric productivity (in two-stage processes) depending on which of the performance measures is more crucial for the process and product of interest.
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Affiliation(s)
- Simon Boecker
- Analysis and Redesign of Biological Networks, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106, Magdeburg, Germany
| | - Ahmed Zahoor
- Analysis and Redesign of Biological Networks, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106, Magdeburg, Germany
| | - Thorben Schramm
- Dynamic Control of Metabolic Networks, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 16, 35043, Marburg, Germany
| | - Hannes Link
- Dynamic Control of Metabolic Networks, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Str. 16, 35043, Marburg, Germany
| | - Steffen Klamt
- Analysis and Redesign of Biological Networks, Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstr. 1, 39106, Magdeburg, Germany
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27
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Wehrs M, Tanjore D, Eng T, Lievense J, Pray TR, Mukhopadhyay A. Engineering Robust Production Microbes for Large-Scale Cultivation. Trends Microbiol 2019; 27:524-537. [PMID: 30819548 DOI: 10.1016/j.tim.2019.01.006] [Citation(s) in RCA: 119] [Impact Index Per Article: 23.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 01/11/2019] [Accepted: 01/23/2019] [Indexed: 11/27/2022]
Abstract
Systems biology and synthetic biology are increasingly used to examine and modulate complex biological systems. As such, many issues arising during scaling-up microbial production processes can be addressed using these approaches. We review differences between laboratory-scale cultures and larger-scale processes to provide a perspective on those strain characteristics that are especially important during scaling. Systems biology has been used to examine a range of microbial systems for their response in bioreactors to fluctuations in nutrients, dissolved gases, and other stresses. Synthetic biology has been used both to assess and modulate strain response, and to engineer strains to improve production. We discuss these approaches and tools in the context of their use in engineering robust microbes for applications in large-scale production.
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Affiliation(s)
- Maren Wehrs
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Institut für Genetik, Technische Universität Braunschweig, Braunschweig, Germany; Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA 94608, USA
| | - Deepti Tanjore
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Advanced Biofuels and Bioproducts Process Development Unit, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Thomas Eng
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA 94608, USA
| | | | - Todd R Pray
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Advanced Biofuels and Bioproducts Process Development Unit, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Aindrila Mukhopadhyay
- Biological Systems and Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA; Joint BioEnergy Institute, Lawrence Berkeley National Laboratory, Emeryville, CA 94608, USA; Environmental Genomics and Systems Biology Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
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28
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Increasing carbon source uptake rates to improve chemical productivity in metabolic engineering. Curr Opin Biotechnol 2018; 53:254-263. [DOI: 10.1016/j.copbio.2018.06.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 05/22/2018] [Accepted: 06/13/2018] [Indexed: 11/24/2022]
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29
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NandaKafle G, Christie AA, Vilain S, Brözel VS. Growth and Extended Survival of Escherichia coli O157:H7 in Soil Organic Matter. Front Microbiol 2018; 9:762. [PMID: 29740410 PMCID: PMC5924783 DOI: 10.3389/fmicb.2018.00762] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2018] [Accepted: 04/04/2018] [Indexed: 12/02/2022] Open
Abstract
Enterohaemorrhagic Escherichia coli, such as serotype O157:H7, are a leading cause of food-associated outbreaks. While the primary reservoir is associated with cattle, plant foods have been associated as sources of human infection. E. coli is able to grow in the tissue of food plants such as spinach. While fecal contamination is the primary suspect, soil has been underestimated as a potential reservoir. Persistence of bacterial populations in open systems is the product of growth, death, predation, and competition. Here we report that E. coli O157:H7 can grow using the soluble compounds in soil, and characterize the effect of soil growth on the stationary phase proteome. E. coli 933D (stxII−) was cultured in Soil Extracted Soluble Organic Matter (SESOM) and the culturable count determined for 24d. The proteomes of exponential and stationary phase populations were characterized by 2D gel electrophoresis and protein spots were identified by MALDI-TOF mass spectrometry. While LB controls displayed a death phase, SESOM grown population remained culturable for 24d, indicating an altered physiological state with superior longevity. This was not due to decreased cell density on entry to stationary phase as 24 h SESOM populations concentrated 10-fold retained their longevity. Principal component analysis showed that stationary phase proteomes from SESOM and LB were different. Differences included proteins involved in stress response, motility, membrane and wall composition, nutrient uptake, translation and protein turnover, and anabolic and catabolic pathways, indicating an altered physiological state of soil-grown cells entering stationary phase. The results suggest that E. coli may be a soil commensal that, in absence of predation and competition, maintains stable populations in soil.
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Affiliation(s)
- Gitanjali NandaKafle
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD, United States
| | - Amy A Christie
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD, United States
| | - Sébastien Vilain
- Spectrométrie de Masse des Macromolécules Biologiques, Chimie Biologie des Membranes et Nanoobjets, UMR Centre National de la Recherche Scientifique 5248, Institut National Polytechnique de Bordeaux, Université de Bordeaux, Bordeaux, France.,Plateforme Protéome, Centre Génomique Fonctionnelle de Bordeaux, Université de Bordeaux, Bordeaux, France
| | - Volker S Brözel
- Department of Biology and Microbiology, South Dakota State University, Brookings, SD, United States.,Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Gauteng, South Africa
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Klamt S, Mahadevan R, Hädicke O. When Do Two-Stage Processes Outperform One-Stage Processes? Biotechnol J 2017; 13. [PMID: 29131522 DOI: 10.1002/biot.201700539] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2017] [Revised: 10/26/2017] [Indexed: 12/30/2022]
Abstract
Apart from product yield and titer, volumetric productivity is a key performance indicator for many biotechnological processes. Due to the inherent trade-off between the production of biomass as catalyst and of the actual target product, yield and volumetric productivity cannot be optimized simultaneously. Therefore, in combination with genetic techniques for dynamic regulation of metabolic fluxes, two-stage fermentations (TSFs) with separated growth and production phase have recently gained much interest because of their potential to improve the productivity of bioprocesses while still allowing high product yields. However, despite some successful case studies, so far it has not been discussed and analyzed systematically whether or under which conditions a TSF guarantees superior productivity compared to one-stage fermentation (OSF). In this study, we use mathematical models to demonstrate that the volumetric productivity of a TSF is not automatically better than of a corresponding OSF. Our analysis reveals that the sharp decrease of the specific substrate uptake rate usually observed in (non-growth) production phases severely impacts the volumetric productivity and thus raises a big challenge for designing competitive TSF processes. We discuss possible approaches such as enforced ATP wasting to improve substrate utilization rates in the production phase by which TSF processes can become superior to OSF. We also analyze additional factors influencing the relative performance of OSF and TSF and show that OSF processes can be more appropriate if a high product yield is an economic constraint. In conclusion, a careful assessment of the trade-offs between substrate uptake rates, yields, and productivity is necessary when deciding for OSF vs. TSF processes.
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Affiliation(s)
- Steffen Klamt
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106 Magdeburg, Germany
| | - Radhakrishnan Mahadevan
- Department of Chemical Engineering & Applied Chemistry, Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada
| | - Oliver Hädicke
- Max Planck Institute for Dynamics of Complex Technical Systems, Sandtorstraße 1, 39106 Magdeburg, Germany
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