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Moulin SLY, Frail S, Braukmann T, Doenier J, Steele-Ogus M, Marks JC, Mills MM, Yeh E. The endosymbiont of Epithemia clementina is specialized for nitrogen fixation within a photosynthetic eukaryote. ISME COMMUNICATIONS 2024; 4:ycae055. [PMID: 38707843 PMCID: PMC11070190 DOI: 10.1093/ismeco/ycae055] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2024] [Revised: 04/05/2024] [Accepted: 04/08/2024] [Indexed: 05/07/2024]
Abstract
Epithemia spp. diatoms contain obligate, nitrogen-fixing endosymbionts, or diazoplasts, derived from cyanobacteria. These algae are a rare example of photosynthetic eukaryotes that have successfully coupled oxygenic photosynthesis with oxygen-sensitive nitrogenase activity. Here, we report a newly-isolated species, E. clementina, as a model to investigate endosymbiotic acquisition of nitrogen fixation. We demonstrate that the diazoplast, which has lost photosynthesis, provides fixed nitrogen to the diatom host in exchange for fixed carbon. To identify the metabolic changes associated with this endosymbiotic specialization, we compared the Epithemia diazoplast with its close, free-living cyanobacterial relative, Crocosphaera subtropica. Unlike C. subtropica, in which nitrogenase activity is temporally separated from photosynthesis, we show that nitrogenase activity in the diazoplast is continuous through the day (concurrent with host photosynthesis) and night. Host and diazoplast metabolism are tightly coupled to support nitrogenase activity: Inhibition of photosynthesis abolishes daytime nitrogenase activity, while nighttime nitrogenase activity no longer requires cyanobacterial glycogen storage pathways. Instead, import of host-derived carbohydrates supports nitrogenase activity throughout the day-night cycle. Carbohydrate metabolism is streamlined in the diazoplast compared to C. subtropica with retention of the oxidative pentose phosphate pathway and oxidative phosphorylation. Similar to heterocysts, these pathways may be optimized to support nitrogenase activity, providing reducing equivalents and ATP and consuming oxygen. Our results demonstrate that the diazoplast is specialized for endosymbiotic nitrogen fixation. Altogether, we establish a new model for studying endosymbiosis, perform a functional characterization of this diazotroph endosymbiosis, and identify metabolic adaptations for endosymbiotic acquisition of a critical biological function.
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Affiliation(s)
- Solène L Y Moulin
- Department of Pathology, Stanford School of Medicine, Stanford, CA 94305, United States
| | - Sarah Frail
- Department of Biochemistry, Stanford School of Medicine, Stanford, CA 94305, United States
| | - Thomas Braukmann
- Department of Pathology, Stanford School of Medicine, Stanford, CA 94305, United States
- Department of Biochemistry, Stanford School of Medicine, Stanford, CA 94305, United States
| | - Jon Doenier
- Department of Biochemistry, Stanford School of Medicine, Stanford, CA 94305, United States
| | - Melissa Steele-Ogus
- Department of Pathology, Stanford School of Medicine, Stanford, CA 94305, United States
| | - Jane C Marks
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AR 86011, United States
- Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ 86011, United States
| | - Matthew M Mills
- Department of Earth System Science, Stanford Doerr School of Sustainability, Stanford, CA 94305, United States
| | - Ellen Yeh
- Department of Pathology, Stanford School of Medicine, Stanford, CA 94305, United States
- Department of Microbiology & Immunology, Stanford School of Medicine, Stanford, CA 94305, United States
- Chan Zuckerberg Biohub, San Francisco, CA 94158, United States
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2
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Stebegg R, Schmetterer G, Rompel A. Heterotrophy among Cyanobacteria. ACS OMEGA 2023; 8:33098-33114. [PMID: 37744813 PMCID: PMC10515406 DOI: 10.1021/acsomega.3c02205] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/02/2023] [Accepted: 07/10/2023] [Indexed: 09/26/2023]
Abstract
Cyanobacteria have been studied in recent decades to investigate the principle mechanisms of plant-type oxygenic photosynthesis, as they are the inventors of this process, and their cultivation and research is much easier compared to land plants. Nevertheless, many cyanobacterial strains possess the capacity for at least some forms of heterotrophic growth. This review demonstrates that cyanobacteria are much more than simple photoautotrophs, and their flexibility toward different environmental conditions has been underestimated in the past. It summarizes the strains capable of heterotrophy known by date structured by their phylogeny and lists the possible substrates for heterotrophy for each of them in a table in the Supporting Information. The conditions are discussed in detail that cause heterotrophic growth for each strain in order to allow for reproduction of the results. The review explains the importance of this knowledge for the use of new methods of cyanobacterial cultivation, which may be advantageous under certain conditions. It seeks to stimulate other researchers to identify new strains capable of heterotrophy that have not been known so far.
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Affiliation(s)
- Ronald Stebegg
- Universität Wien, Fakultät für Chemie, Institut für
Biophysikalische Chemie, 1090 Wien, Austria
| | - Georg Schmetterer
- Universität Wien, Fakultät für Chemie, Institut für
Biophysikalische Chemie, 1090 Wien, Austria
| | - Annette Rompel
- Universität Wien, Fakultät für Chemie, Institut für
Biophysikalische Chemie, 1090 Wien, Austria
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3
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Plesh SP, Lovvorn JR, Miller MWC. Organic matter sources and flows in tundra wetland food webs. PLoS One 2023; 18:e0286368. [PMID: 37235582 DOI: 10.1371/journal.pone.0286368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2022] [Accepted: 05/15/2023] [Indexed: 05/28/2023] Open
Abstract
Arctic lowland tundra is often dominated by wetlands. As numbers and types of these wetlands change with climate warming, their invertebrate biomass and assemblages may also be affected. Increased influx of nutrients and dissolved organic matter (DOM) from thawing peat may alter the relative availability of organic matter (OM) sources, differentially affecting taxa with disparate dependence on those sources. In five shallow wetland types (<40 to 110 cm deep) and in littoral zones of deeper lakes (>150 cm), we used stable isotopes (δ13C, δ15N) to compare contributions of four OM sources (periphytic microalgae, cyanobacteria, macrophytes, peat) to the diets of nine macroinvertebrate taxa. Living macrophytes were not distinguishable isotopically from peat that likely contributed most DOM. Within invertebrate taxa, relative OM contributions were similar among all wetland types except deeper lakes. Physidae snails consumed substantial amounts of OM from cyanobacteria. However, for all other taxa examined, microalgae were the dominant or a major OM source (39-82%, mean 59%) in all wetland types except deeper lakes (20‒62%, mean 31%). Macrophytes and macrophyte-derived peat, likely consumed mostly indirectly as DOM-supported bacteria, ranged from 18‒61% (mean 41%) of ultimate OM sources in all wetland types except deeper lakes (38-80%, mean 69%). Invertebrate consumption of microalgal C may often have involved bacterial intermediates, or a mix of algae with bacteria consuming peat-derived OM. High production of periphyton with very low δ13C values were favored by continuous daylight illuminating shallow depths, high N and P levels, and high CO2 concentrations from bacterial respiration of peat-derived DOM. Although relative OM sources were similar across wetland types except deeper lakes, total invertebrate biomass was much higher in shallow wetlands with emergent vegetation. Impacts of warming on the availability of invertebrate prey to waterbirds will likely depend not on shifts in OM sources, but more on changes in overall number or area of shallow emergent wetlands.
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Affiliation(s)
- Steven P Plesh
- School of Biological Sciences, Southern Illinois University, Carbondale, Illinois, United States of America
| | - James R Lovvorn
- School of Biological Sciences, Southern Illinois University, Carbondale, Illinois, United States of America
| | - Micah W C Miller
- School of Biological Sciences, Southern Illinois University, Carbondale, Illinois, United States of America
- United States Fish and Wildlife Service, Fairbanks Fish and Wildlife Field Office, Fairbanks, Alaska, United States of America
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4
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Moulin SL, Frail S, Doenier J, Braukmann T, Yeh E. The endosymbiont of Epithemia clementina is specialized for nitrogen fixation within a photosynthetic eukaryote. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.03.08.531752. [PMID: 37066385 PMCID: PMC10103950 DOI: 10.1101/2023.03.08.531752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/19/2023]
Abstract
Epithemia spp. diatoms contain obligate, nitrogen-fixing endosymbionts, or "diazoplasts", derived from cyanobacteria. These algae are a rare example of photosynthetic eukaryotes that have successfully coupled oxygenic photosynthesis with oxygen-sensitive nitrogenase activity. Here, we report a newly-isolated species, E. clementina, as a model to investigate endosymbiotic acquisition of nitrogen fixation. To detect the metabolic changes associated with endosymbiotic specialization, we compared nitrogen fixation, associated carbon and nitrogen metabolism, and their regulatory pathways in the Epithemia diazoplast with its close, free-living cyanobacterial relative, Crocosphaera subtropica. Unlike C. subtropica, we show that nitrogenase activity in the diazoplast is concurrent with, and even dependent on, host photosynthesis and no longer associated with cyanobacterial glycogen storage suggesting carbohydrates are imported from the host diatom. Carbohydrate catabolism in the diazoplast indicates that the oxidative pentose pathway and oxidative phosphorylation, in concert, generates reducing equivalents and ATP and consumes oxygen to support nitrogenase activity. In contrast to expanded nitrogenase activity, the diazoplast has diminished ability to utilize alternative nitrogen sources. Upon ammonium repletion, negative feedback regulation of nitrogen fixation was conserved, however ammonia assimilation showed paradoxical responses in the diazoplast compared with C. subtropica. The altered nitrogen regulation likely favors nitrogen transfer to the host. Our results suggest that the diazoplast is specialized for endosymbiotic nitrogen fixation. Altogether, we establish a new model for studying endosymbiosis, perform the first functional characterization of this diazotroph endosymbiosis, and identify metabolic adaptations for endosymbiotic acquisition of a critical biological function.
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Affiliation(s)
- Solène L.Y. Moulin
- Department of Pathology, Stanford School of Medicine, Stanford, California, USA
| | - Sarah Frail
- Department of Biochemistry, Stanford School of Medicine, Stanford, California, USA
| | - Jon Doenier
- Department of Biochemistry, Stanford School of Medicine, Stanford, California, USA
| | - Thomas Braukmann
- Department of Pathology, Stanford School of Medicine, Stanford, California, USA
- Department of Biochemistry, Stanford School of Medicine, Stanford, California, USA
| | - Ellen Yeh
- Department of Pathology, Stanford School of Medicine, Stanford, California, USA
- Department of Microbiology & Immunology, Stanford School of Medicine, Stanford, California, USA
- Chan Zuckerberg Biohub – San Francisco, San Francisco, CA 94158
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5
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Xiao Z, Tan AX, Xu V, Jun YS, Tang YJ. Mineral-hydrogel composites for mitigating harmful algal bloom and supplying phosphorous for photo-biorefineries. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 847:157533. [PMID: 35878849 PMCID: PMC9755271 DOI: 10.1016/j.scitotenv.2022.157533] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/16/2022] [Accepted: 07/17/2022] [Indexed: 06/15/2023]
Abstract
Harmful algal blooms (HAB) are a major environmental concern in eutrophic aquatic systems. To mitigate HABs and recover the phosphorus that drives algal growth, this study developed hydrogel composites seeded with calcium phosphate and wollastonite particles, which first adsorb phosphate (P) and then precipitate it as calcium phosphate. Using a fast-growing cyanobacterium, Synechococcus elongatus 2973, as a model microalga, we found that the mineral-hydrogel composites reduced dissolved P in BG11 media from 5.1 mg/L to 0.31 mg/L, initially reducing the biomass growth rate by up to 73 % and ultimately reducing the total biomass concentration by 75 %. When applied to municipal wastewater and agricultural run-off, the composites removed 96 % and 91 % of the dissolved P, respectively. Moreover, when the recovered P-enriched composites were reused as a slow-release bio-compatible fertilizer in a photobioreactor, they effectively supported algal growth without blocking light and interfering with photosynthesis. The P-enriched composites could tune the P concentration in the culture medium and significantly promote algal lipid accumulation. This study demonstrates the mineral-hydrogel composites' potential to treat point sources of P pollution and subsequently facilitate photoautotrophic biofuel production as a nutrient, effectively recycling the captured P.
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Affiliation(s)
- Zhengyang Xiao
- Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO, 63130, USA
| | - Albern X Tan
- Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO, 63130, USA
| | - Vincent Xu
- Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO, 63130, USA
| | - Young-Shin Jun
- Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO, 63130, USA.
| | - Yinjie J Tang
- Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO, 63130, USA.
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6
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Nirati Y, Purushotham N, Alagesan S. Quantitative insight into the metabolism of isoprene-producing Synechocystis sp. PCC 6803 using steady state 13C-MFA. PHOTOSYNTHESIS RESEARCH 2022; 154:195-206. [PMID: 36070060 DOI: 10.1007/s11120-022-00957-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Accepted: 08/24/2022] [Indexed: 06/15/2023]
Abstract
Cyanobacteria are photosynthetic bacteria, widely studied for the conversion of atmospheric carbon dioxide to useful platform chemicals. Isoprene is one such industrially important chemical, primarily used for production of synthetic rubber and biofuels. Synechocystis sp. PCC 6803, a genetically amenable cyanobacterium, produces isoprene on heterologous expression of isoprene synthase gene, albeit in very low quantities. Rationalized metabolic engineering to re-route the carbon flux for enhanced isoprene production requires in-dept knowledge of the metabolic flux distribution in the cell. Hence, in the present study, we undertook steady state 13C-metabolic flux analysis of glucose-tolerant wild-type (GTN) and isoprene-producing recombinant (ISP) Synechocystis sp. to understand and compare the carbon flux distribution in the two strains. The R-values for amino acids, flux analysis predictions and gene expression profiles emphasized predominance of Calvin cycle and glycogen metabolism in GTN. Alternatively, flux analysis predicted higher activity of the anaplerotic pathway through phosphoenolpyruvate carboxylase and malic enzyme in ISP. The striking difference in the Calvin cycle, glycogen metabolism and anaplerotic pathway activity in GTN and ISP suggested a possible role of energy molecules (ATP and NADPH) in regulating the carbon flux distribution in GTN and ISP. This claim was further supported by the transcript level of selected genes of the electron transport chain. This study provides the first quantitative insight into the carbon flux distribution of isoprene-producing cyanobacterium, information critical for developing Synechocystis sp. as a single cell factory for isoprenoid/terpenoid production.
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Affiliation(s)
- Yasha Nirati
- Institute of Bioinformatics and Applied Biotechnology (IBAB), Bengaluru, 560100, India
| | - Nidhish Purushotham
- Institute of Bioinformatics and Applied Biotechnology (IBAB), Bengaluru, 560100, India
- Dayananda Sagar University, Bengaluru, India
| | - Swathi Alagesan
- Institute of Bioinformatics and Applied Biotechnology (IBAB), Bengaluru, 560100, India.
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7
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Van Camp C, Fraikin C, Claverie E, Onderwater R, Wattiez R. Capsular polysaccharides and exopolysaccharides from Gloeothece verrucosa under various nitrogen regimes and their potential plant defence stimulation activity. ALGAL RES 2022. [DOI: 10.1016/j.algal.2022.102680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022]
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8
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Benavides M, Duhamel S, Van Wambeke F, Shoemaker KM, Moisander PH, Salamon E, Riemann L, Bonnet S. Dissolved organic matter stimulates N2 fixation and nifH gene expression in Trichodesmium. FEMS Microbiol Lett 2021; 367:5743415. [PMID: 32083662 DOI: 10.1093/femsle/fnaa034] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Accepted: 02/20/2020] [Indexed: 12/15/2022] Open
Abstract
Mixotrophy, the combination of heterotrophic and autotrophic nutrition modes, is emerging as the rule rather than the exception in marine photosynthetic plankton. Trichodesmium, a prominent diazotroph ubiquitous in the (sub)tropical oceans, is generally considered to obtain energy via autotrophy. While the ability of Trichodesmium to use dissolved organic phosphorus when deprived of inorganic phosphorus sources is well known, the extent to which this important cyanobacterium may benefit from other dissolved organic matter (DOM) resources is unknown. Here we provide evidence of carbon-, nitrogen- and phosphorus-rich DOM molecules enhancing N2 fixation rates and nifH gene expression in natural Trichodesmium colonies collected at two stations in the western tropical South Pacific. Sampling at a third station located in the oligotrophic South Pacific Gyre revealed no Trichodesmium but showed presence of UCYN-B, although no nifH expression was detected. Our results suggest that Trichodesmium behaves mixotrophically in response to certain environmental conditions, providing them with metabolic plasticity and adding up to the view that mixotrophy is widespread among marine microbes.
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Affiliation(s)
- Mar Benavides
- Aix Marseille Univ., Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Solange Duhamel
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA
| | - France Van Wambeke
- Aix Marseille Univ., Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
| | - Katyanne M Shoemaker
- Department of Biology, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA
| | - Pia H Moisander
- Department of Biology, University of Massachusetts Dartmouth, 285 Old Westport Road, North Dartmouth, MA 02747, USA
| | - Ellen Salamon
- Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark
| | - Lasse Riemann
- Department of Biology, University of Copenhagen, Strandpromenaden 5, 3000 Helsingør, Denmark
| | - Sophie Bonnet
- Aix Marseille Univ., Université de Toulon, CNRS, IRD, MIO UM 110, 13288, Marseille, France
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9
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Strieth D, Schwarz A, Stiefelmaier J, Erdmann N, Muffler K, Ulber R. New procedure for separation and analysis of the main components of cyanobacterial EPS. J Biotechnol 2021; 328:78-86. [PMID: 33484743 DOI: 10.1016/j.jbiotec.2021.01.007] [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: 12/02/2020] [Revised: 01/08/2021] [Accepted: 01/09/2021] [Indexed: 11/25/2022]
Abstract
Phototrophic biofilms produce a matrix of extracellular polymeric substances (EPS), which holds the cells together and functions inter alia as nutrient storage and protection layer. EPS mainly consist of water, polysaccharides, proteins, lipids and nucleic acids as well as lysis and hydrolysis products which makes the composition very complex. Thus, rough simplifications are used and commonly one or at most two components of the EPS are examined. In this work a new procedure for separation and analysis of EPS in the main components (i) polysaccharides, (ii) proteins and (iii) lipids is presented with recovery rates of nearly 100 %. The method was established with synthetic EPS, which based on the composition of real EPS described in literature. Afterwards, the method was transferred to real EPS samples allowing a deeper insight in the composition of EPS from only one sample. The composition of EPS-extracts from Nostoc spec, cultivated under heterotrophic and mixotrophic batch and fed-batch conditions, was analysed during a cultivation period of 14 days. It was observed that mixotrophic cultivation led to higher amounts of carbohydrates, lipids and proteins than heterotrophic cultivation respectively, regardless of batch or fed-batch culture. While the amount of proteins in the EPS increased during the cultivation period, carbohydrates and lipids were dominant in the beginning and decreased afterwards.
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Affiliation(s)
- Dorina Strieth
- Technical University of Kaiserslautern, Chair of Bioprocess Engineering, Gottlieb-Daimler-Str. 49, 67663, Kaiserslautern, Germany.
| | - Anna Schwarz
- University of Applied Sciences Bingen, Department of Life Sciences and Engineering, 55411, Bingen am Rhein, Germany
| | - Judith Stiefelmaier
- Technical University of Kaiserslautern, Chair of Bioprocess Engineering, Gottlieb-Daimler-Str. 49, 67663, Kaiserslautern, Germany
| | - Niklas Erdmann
- Technical University of Kaiserslautern, Chair of Bioprocess Engineering, Gottlieb-Daimler-Str. 49, 67663, Kaiserslautern, Germany
| | - Kai Muffler
- University of Applied Sciences Bingen, Department of Life Sciences and Engineering, 55411, Bingen am Rhein, Germany
| | - Roland Ulber
- Technical University of Kaiserslautern, Chair of Bioprocess Engineering, Gottlieb-Daimler-Str. 49, 67663, Kaiserslautern, Germany
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10
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Adjustments of the photosynthetic unit and compensation mechanisms of tolerance to high ammonia concentration in Chlorella sp. grown in food waste digestate. ALGAL RES 2020. [DOI: 10.1016/j.algal.2020.102106] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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11
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Influence of heterotrophic and mixotrophic cultivation on growth behaviour of terrestrial cyanobacteria. ALGAL RES 2020. [DOI: 10.1016/j.algal.2020.102125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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12
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Geisler E, Bogler A, Bar-Zeev E, Rahav E. Heterotrophic Nitrogen Fixation at the Hyper-Eutrophic Qishon River and Estuary System. Front Microbiol 2020; 11:1370. [PMID: 32670236 PMCID: PMC7326945 DOI: 10.3389/fmicb.2020.01370] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2020] [Accepted: 05/27/2020] [Indexed: 12/04/2022] Open
Abstract
Planktonic heterotrophic diazotrophs (N2-fixers) are widely distributed in marine and freshwater systems, yet limited information is available on their activity, especially in environments with adverse conditions for diazotrophy (e.g., N-rich and oxygenated). Here, we followed the localization and activity of heterotrophic diazotrophs in the hyper-eutrophic N-rich Qishon River—an environment previously considered to be unfavorable for diazotrophy. Our results indicate high heterotrophic N2 fixation rates (up to 6.9 nmol N L–1 d–1), which were approximately three fold higher at an upstream location (freshwater) compared to an estuary (brackish) site. Further, active heterotrophic diazotrophs were capture associated with free-floating aggregates by a newly developed immunolocalization approach. These findings provide new insights on the activity of heterotrophic diazotrophs on aggregates in environments previously considered with adverse conditions for diazotrophy. Moreover, these new insights may be applicable to other aquatic regimes worldwide with similar N-rich/oxygenated conditions that should potentially inhibit N2 fixation.
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Affiliation(s)
- Eyal Geisler
- The Zuckerberg Institute for Water Research (ZIWR), The Jacob Blaustein Institutes for Desert Research (BIDR), Ben-Gurion University of the Negev, Beer-Sheva, Israel.,Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, Israel
| | - Anne Bogler
- The Zuckerberg Institute for Water Research (ZIWR), The Jacob Blaustein Institutes for Desert Research (BIDR), Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Edo Bar-Zeev
- The Zuckerberg Institute for Water Research (ZIWR), The Jacob Blaustein Institutes for Desert Research (BIDR), Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Eyal Rahav
- Israel Oceanographic and Limnological Research, National Institute of Oceanography, Haifa, Israel
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13
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Wu C, Herold RA, Knoshaug EP, Wang B, Xiong W, Laurens LML. Fluxomic Analysis Reveals Central Carbon Metabolism Adaptation for Diazotroph Azotobacter vinelandii Ammonium Excretion. Sci Rep 2019; 9:13209. [PMID: 31520074 PMCID: PMC6744558 DOI: 10.1038/s41598-019-49717-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 08/30/2019] [Indexed: 11/09/2022] Open
Abstract
Diazotrophic bacteria are an attractive biological alternative to synthetic nitrogen fertilizers due to their remarkable capacity to fix atmospheric nitrogen gas to ammonium via nitrogenase enzymes. However, how diazotrophic bacteria tailor central carbon catabolism to accommodate the energy requirement for nitrogenase activity is largely unknown. In this study, we used Azotobacter vinelandii DJ and an ammonium excreting mutant, AV3 (ΔNifL), to investigate central carbon metabolism fluxes and central cell bioenergetics in response to ammonium availability and nitrogenase activity. Enabled by the powerful and reliable methodology of 13C-metabolic flux analysis, we show that the respiratory TCA cycle is upregulated in association with increased nitrogenase activity and causes a monotonic decrease in specific growth rate. Whereas the activity of the glycolytic Entner-Doudoroff pathway is positively correlated with the cell growth rate. These new observations are formulated into a 13C-metabolic flux model which further improves the understanding and interpretation of intracellular bioenergetics. This analysis leads to the conclusion that, under aerobic conditions, respiratory TCA metabolism is responsible for the supply of additional ATP and reducing equivalents required for elevated nitrogenase activity. This study provides a quantitative relationship between central carbon and nitrogen metabolism in an aerobic diazotroph for the first time.
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Affiliation(s)
- Chao Wu
- Bioenergy Science and Technology Directorate, National Renewable Energy Laboratory (NREL), 15013, Denver West Parkway, Golden, CO, 80401, USA
| | - Ryan A Herold
- Bioenergy Science and Technology Directorate, National Renewable Energy Laboratory (NREL), 15013, Denver West Parkway, Golden, CO, 80401, USA
| | - Eric P Knoshaug
- Bioenergy Science and Technology Directorate, National Renewable Energy Laboratory (NREL), 15013, Denver West Parkway, Golden, CO, 80401, USA
| | - Bo Wang
- Bioenergy Science and Technology Directorate, National Renewable Energy Laboratory (NREL), 15013, Denver West Parkway, Golden, CO, 80401, USA
| | - Wei Xiong
- Bioenergy Science and Technology Directorate, National Renewable Energy Laboratory (NREL), 15013, Denver West Parkway, Golden, CO, 80401, USA.
| | - Lieve M L Laurens
- Bioenergy Science and Technology Directorate, National Renewable Energy Laboratory (NREL), 15013, Denver West Parkway, Golden, CO, 80401, USA.
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14
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Cyanobacteria as Nanogold Factories II: Chemical Reactivity and anti-Myocardial Infraction Properties of Customized Gold Nanoparticles Biosynthesized by Cyanothece sp. Mar Drugs 2019; 17:md17070402. [PMID: 31288394 PMCID: PMC6669522 DOI: 10.3390/md17070402] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 05/22/2019] [Accepted: 07/01/2019] [Indexed: 01/08/2023] Open
Abstract
Cyanothece sp., a coccoid, unicellular, nitrogen-fixing and hydrogen-producing cyanobacterium, has been used in this study to biosynthesize customized gold nanoparticles under certain chemical conditions. The produced gold nanoparticles had a characteristic absorption band at 525–535 nm. Two types of gold nanoparticle, the purple and blue, were formed according to the chemical environment in which the cyanobacterium was grown. Dynamic light scattering was implemented to estimate the size of the purple and blue nanoparticles, which ranged from 80 ± 30 nm and 129 ± 40 nm in diameter, respectively. The highest scattering of laser light was recorded for the blue gold nanoparticles, which was possibly due to their larger size and higher concentration. The appearance of anodic and cathodic peaks in cyclic voltammetric scans of the blue gold nanoparticles reflected the oxidation into gold oxide, followed by the subsequent reduction into the nano metal state. The two produced forms of gold nanoparticles were used to treat isoproterenol-induced myocardial infarction in experimental rats. Both forms of nanoparticles ameliorated myocardial infarction injury, with a slight difference in their curative activity with the purple being more effective. Mechanisms that might explain the curative effect of these nanoparticles on the myocardial infarction were proposed. The morphological, physiological, and biochemical attributes of the Cyanothece sp. cyanobacterium were fundamental for the successful production of “tailored” nanoparticles, and complemented the chemical conditions for the differential biosynthesis process. The present research represents a novel approach to manipulate cyanobacterial cells towards the production of different-sized gold nanoparticles whose curative impacts vary accordingly. This is the first report on that type of manipulated gold nanoparticles biosynthesis which will hopefully open doors for further investigations and biotechnological applications.
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Stebegg R, Schmetterer G, Rompel A. Transport of organic substances through the cytoplasmic membrane of cyanobacteria. PHYTOCHEMISTRY 2019; 157:206-218. [PMID: 30447471 DOI: 10.1016/j.phytochem.2018.08.013] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 07/25/2018] [Accepted: 08/17/2018] [Indexed: 06/09/2023]
Abstract
Cyanobacteria are mainly known to incorporate inorganic molecules like carbon dioxide and ammonia from the environment into organic material within the cell. Nevertheless cyanobacteria do import and export organic substances through the cytoplasmic membrane and these processes are essential for all cyanobacteria. In addition understanding the mechanisms of transport of organic molecules through the cytoplasmic membrane might become very important. Genetically modified strains of cyanobacteria could serve as producers and exporters of commercially important substances. In this review we attempt to present all data of transport of organic molecules through the cytoplasmic membrane of cyanobacteria that are currently available with the transported molecules ordered according to their chemical classes.
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Affiliation(s)
- Ronald Stebegg
- Universität Wien, Fakultät für Chemie, Institut für Biophysikalische Chemie, Althanstraße 14, 1090 Wien, Austria(1).
| | - Georg Schmetterer
- Universität Wien, Fakultät für Chemie, Institut für Biophysikalische Chemie, Althanstraße 14, 1090 Wien, Austria(1).
| | - Annette Rompel
- Universität Wien, Fakultät für Chemie, Institut für Biophysikalische Chemie, Althanstraße 14, 1090 Wien, Austria(1).
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16
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Phycocyanin Production by Aphanothece microscopica Nägeli in Synthetic Medium Supplemented with Sugarcane Vinasse. Appl Biochem Biotechnol 2018; 187:129-139. [PMID: 29911264 DOI: 10.1007/s12010-018-2811-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2018] [Accepted: 06/05/2018] [Indexed: 01/30/2023]
Abstract
This study focused on the evaluation of mixotrophic and heterotrophic production of phycocyanin by A. microscopica, analysis of kinetic parameters, the effect of freezing and thawing on phycocyanin yield, and nutrient removal during heterotrophic growth. During mixotrophic growth, maximum phycocyanin yield (1.50 mgphycocyanin g-1biomass) was obtained after 12 h, while the heterotrophic cultivation yielded 1.39 mgphycocyanin g-1biomass. The mixotrophic cultivation of A. microscopica showed maximum specific growth rate of 0.025 h-1, against 0.010 h-1 for the photoautotrophic cultivation, and 0.08 h-1 in heterotrophic conditions. The mixotrophic cultivation had a specific rate of phycocyanin production of 9.86 mgphycocyanin mgbiomass-1 h-1, while the photoautotrophic had 2.81 mgphycocyanin mgbiomass-1 h-1, and the heterotrophic, 49.18 mgphycocyanin mgbiomass-1 h-1. Carbon and nitrogen contents present in sugarcane vinasse were decreased in 16.69 and 15.97%, respectively, after 6 h of heterotrophic growth. Thus, it was shown that the mixotrophic production of phycocyanin by Aphanothece microscopica Nägeli in BG11 medium supplemented with vinasse is feasible.
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17
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Elucidation of photoautotrophic carbon flux topology in Synechocystis PCC 6803 using genome-scale carbon mapping models. Metab Eng 2018. [DOI: 10.1016/j.ymben.2018.03.008] [Citation(s) in RCA: 39] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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18
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Alagesan S, Minton NP, Malys N. 13C-assisted metabolic flux analysis to investigate heterotrophic and mixotrophic metabolism in Cupriavidus necator H16. Metabolomics 2017; 14:9. [PMID: 29238275 PMCID: PMC5715045 DOI: 10.1007/s11306-017-1302-z] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 11/22/2017] [Indexed: 11/26/2022]
Abstract
INTRODUCTION Cupriavidus necator H16 is a gram-negative bacterium, capable of lithoautotrophic growth by utilizing hydrogen as an energy source and fixing carbon dioxide (CO2) through Calvin-Benson-Bassham (CBB) cycle. The potential to utilize synthesis gas (Syngas) and the prospects of rerouting carbon from polyhydroxybutyrate synthesis to value-added compounds makes C. necator an excellent chassis for industrial application. OBJECTIVES In the context of lack of sufficient quantitative information of the metabolic pathways and to advance in rational metabolic engineering for optimized product synthesis in C. necator H16, we carried out a metabolic flux analysis based on steady-state 13C-labelling. METHODS In this study, steady-state carbon labelling experiments, using either d-[1-13C]fructose or [1,2-13C]glycerol, were undertaken to investigate the carbon flux through the central carbon metabolism in C. necator H16 under heterotrophic and mixotrophic growth conditions, respectively. RESULTS We found that the CBB cycle is active even under heterotrophic condition, and growth is indeed mixotrophic. While Entner-Doudoroff (ED) pathway is shown to be the major route for sugar degradation, tricarboxylic acid (TCA) cycle is highly active in mixotrophic condition. Enhanced flux is observed in reductive pentose phosphate pathway (redPPP) under the mixotrophic condition to supplement the precursor requirement for CBB cycle. The flux distribution was compared to the mRNA abundance of genes encoding enzymes involved in key enzymatic reactions of the central carbon metabolism. CONCLUSION This study leads the way to establishing 13C-based quantitative fluxomics for rational pathway engineering in C. necator H16.
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Affiliation(s)
- Swathi Alagesan
- BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, Centre for Biomolecular Sciences, University Park, The University of Nottingham, Nottingham, NG7 2RD, UK
| | - Nigel P Minton
- BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, Centre for Biomolecular Sciences, University Park, The University of Nottingham, Nottingham, NG7 2RD, UK
| | - Naglis Malys
- BBSRC/EPSRC Synthetic Biology Research Centre (SBRC), School of Life Sciences, Centre for Biomolecular Sciences, University Park, The University of Nottingham, Nottingham, NG7 2RD, UK.
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19
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Kovač D, Babić O, Milovanović I, Mišan A, Simeunović J. The production of biomass and phycobiliprotein pigments in filamentous cyanobacteria: the impact of light and carbon sources. APPL BIOCHEM MICRO+ 2017. [DOI: 10.1134/s000368381705009x] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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20
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Wan N, Sathish A, You L, Tang YJ, Wen Z. Deciphering Clostridium metabolism and its responses to bioreactor mass transfer during syngas fermentation. Sci Rep 2017; 7:10090. [PMID: 28855713 PMCID: PMC5577309 DOI: 10.1038/s41598-017-10312-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2017] [Accepted: 08/07/2017] [Indexed: 12/24/2022] Open
Abstract
This study used 13C tracers and dynamic labeling to reveal metabolic features (nutrients requirements, pathway delineation and metabolite turnover rates) of Clostridium carboxidivorans P7, a model strain for industrial syngas fermentation, and its implication with bioreactor mass transfer. P7 shows poor activity for synthesizing amino acids (e.g., phenylalanine) and thus, needs rich medium for cell growth. The strain has multiple carbon fixation routes (Wood-Ljungdahl pathway, pyruvate:ferredoxin oxidoreductase reaction and anaplerotic pathways) and Re-citrate synthase (Ccar_06155) was a key enzyme in its tricarboxylic acid cycle (TCA) pathway. High fluxes were observed in P7's Wood-Ljungdahl pathway, right branch of TCA cycle, pyruvate synthesis, and sugar phosphate pathways, but the cells anabolic pathways were strikingly slow. In bioreactor culture, when syngas flowrate increased from 1 to 10 mL/min, P7 strain produced same amount of total extracellular products (acids and alcohols) but high flowrate favored alcohol accumulation. This observation was due to the mass transfer limitation influencing energy metabolism (CO/H2 oxidation for cofactor generations) more prominently than carbon fixation. When syngas flowrate increased from 10 of 20 mL/min, the alcohol productivity was not improved and the labeling rate (~0.03 h-1) of key metabolite acetyl-CoA reached to P7 strain's metabolism limitation regime.
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Affiliation(s)
- Ni Wan
- Department of Mechanical Engineering and Materials Science, Washington University, St. Louis, MO, 63130, USA
| | - Ashik Sathish
- Agricultural and Biosystems Engineering Department, Iowa State University, Ames, IA, 50011, USA
| | - Le You
- Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO, 63130, USA
| | - Yinjie J Tang
- Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, MO, 63130, USA.
| | - Zhiyou Wen
- Department of Food Science and Human Nutrition, Iowa State University, Ames, IA, 50011, USA.
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Sewage outburst triggers Trichodesmium bloom and enhance N 2 fixation rates. Sci Rep 2017; 7:4367. [PMID: 28663560 PMCID: PMC5491490 DOI: 10.1038/s41598-017-04622-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 05/25/2017] [Indexed: 11/09/2022] Open
Abstract
The southeastern Mediterranean Sea (SEMS) is a warm and sunlit marine environment with low ambient N concentration, thus considered ideal for diazotrophy by autotrophic diazotrophs such as Trichodesmium. Despite the favorable conditions, N2 fixation rates are often low and Trichodesmium has hardly been spotted in the SEMS. This study reports on the occurrence of a Trichodesmium bloom in the SEMS which was ascribed to T. erythraeum according to DNA fingerprinting of the nifH gene. We found that this bloom (1407 ± 983 cells L−1) was triggered by an intense outburst of raw sewage that supplied high concentrations of N, P and dissolved organic carbon (DOC), which resulted in low N:P (~12:1) and exceptionally high C:P (~1340:1) ratios. We surmise that these conditions provided favorable conditions for Trichodesmium bloom to form via mixotrophic metabolism. As a result, a fourfold increase in N2 fixation was recorded, which contributed ~70% to new primary production and spur a sharp increase in phytoplankton activity and biomass. The conclusions of this study point on a new paradigm for bloom-forming T. erythraeum which is tightly linked to anthropogenic sources and prompt microbial productivity in oligotrophic marine environments such as the SEMS.
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22
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Petushkova EP, Tsygankov AA. Acetate Metabolism in the Purple Non-sulfur Bacterium Rhodobacter capsulatus. BIOCHEMISTRY (MOSCOW) 2017; 82:587-605. [PMID: 28601069 DOI: 10.1134/s0006297917050078] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The purple non-sulfur bacterium Rhodobacter capsulatus B10 can grow on acetate as the sole carbon source under photoheterotrophic conditions. It is known that the bacterium can use the glyoxylate cycle and, in addition to it, or alternatively to it, an unknown pathway for acetate assimilation. We analyzed the genetic potential for functioning of additional metabolic pathways of oxaloacetic acid (OAA) pool replenishment in R. capsulatus. Using published microarray data of more than 4000 transcripts of genes for R. capsulatus, the genes necessary for acetate assimilation were analyzed. The results of the analysis showed the presence of all genes necessary for functioning of the ethylmalonyl-CoA pathway, and also a combination of pathways of formation of pyruvic acid/phosphoenol pyruvate (PA/PEP) (from acetyl-CoA and formate, from acetyl-CoA and CO2, as well as from 3-phosphoglyceric acid formed in the Calvin-Benson cycle) with their subsequent carboxylation. Using expression analysis, we showed that OAA pool replenishment on acetate medium could be achieved via a combination of PA/PEP synthesis from Calvin-Benson cycle intermediates and their carboxylation (with participation of pyruvate carboxylase, two reversible malate dehydrogenases (decarboxylating) and PEP-carboxykinase) to tricarboxylic acid cycle intermediates, the glyoxylate cycle, and a modified ethylmalonyl-CoA pathway in R. capsulatus under these experimental conditions. It was found that analogs of ethylmalonyl-CoA pathway enzymes exist. These enzymes differ in their specificity for S-enantiomers.
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Affiliation(s)
- E P Petushkova
- Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Moscow Region, 142290, Russia.
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23
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Gründel M, Knoop H, Steuer R. Activity and functional properties of the isocitrate lyase in the cyanobacterium Cyanothece sp. PCC 7424. MICROBIOLOGY-SGM 2017; 163:731-744. [PMID: 28516845 DOI: 10.1099/mic.0.000459] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Cyanobacteria are ubiquitous photoautotrophs that assimilate atmospheric CO2 as their main source of carbon. Several cyanobacteria are known to be facultative heterotrophs that are able to grow on diverse carbon sources. For selected strains, assimilation of organic acids and mixotrophic growth on acetate has been reported for decades. However, evidence for the existence of a functional glyoxylate shunt in cyanobacteria has long been contradictory and unclear. Genes coding for isocitrate lyase (ICL) and malate synthase were recently identified in two strains of the genus Cyanothece, and the existence of the complete glyoxylate shunt was verified in a strain of Chlorogloeopsis fritschii. Here, we report that the gene PCC7424_4054 of the strain Cyanothece sp. PCC 7424 encodes an enzymatically active protein that catalyses the reaction of ICL, an enzyme that is specific for the glyoxylate shunt. We demonstrate that ICL activity is induced under alternating day/night cycles and acetate-supplemented cultures exhibit enhanced growth. In contrast, growth under constant light did not result in any detectable ICL activity or enhanced growth of acetate-supplemented cultures. Furthermore, our results indicate that, despite the presence of a glyoxylate shunt, acetate does not support continued heterotrophic growth and cell proliferation. The functional validation of the ICL is supplemented with a bioinformatics analysis of enzymes that co-occur with the glyoxylate shunt. We hypothesize that the glyoxylate shunt in Cyanothece sp. PCC 7424, and possibly other nitrogen-fixing cyanobacteria, is an adaptation to a specific ecological niche and supports assimilation of nitrogen or organic compounds during the night phase.
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Affiliation(s)
- Marianne Gründel
- Fachinstitut Theoretische Biologie (ITB), Institut für Biologie, Humboldt-Universität zu Berlin, Invalidenstraße 43, 10115 Berlin, Germany.,Institut für Biologie, Humboldt-Universität zu Berlin, Chausseestr. 117, 10115 Berlin, Germany
| | - Henning Knoop
- Fachinstitut Theoretische Biologie (ITB), Institut für Biologie, Humboldt-Universität zu Berlin, Invalidenstraße 43, 10115 Berlin, Germany
| | - Ralf Steuer
- Fachinstitut Theoretische Biologie (ITB), Institut für Biologie, Humboldt-Universität zu Berlin, Invalidenstraße 43, 10115 Berlin, Germany
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24
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Dissolved organic matter uptake by Trichodesmium in the Southwest Pacific. Sci Rep 2017; 7:41315. [PMID: 28117432 PMCID: PMC5259775 DOI: 10.1038/srep41315] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Accepted: 12/14/2016] [Indexed: 11/29/2022] Open
Abstract
The globally distributed diazotroph Trichodesmium contributes importantly to nitrogen inputs in the oligotrophic oceans. Sites of dissolved organic matter (DOM) accumulation could promote the mixotrophic nutrition of Trichodesmium when inorganic nutrients are scarce. Nano-scale secondary ion mass spectrometry (nanoSIMS) analyses of individual trichomes sampled in the South Pacific Ocean, showed significant 13C-enrichments after incubation with either 13C-labeled carbohydrates or amino acids. These results suggest that DOM could be directly taken up by Trichodesmium or primarily consumed by heterotrophic epibiont bacteria that ultimately transfer reduced DOM compounds to their host trichomes. Although the addition of carbohydrates or amino acids did not significantly affect bulk N2 fixation rates, N2 fixation was enhanced by amino acids in individual colonies of Trichodesmium. We discuss the ecological advantages of DOM use by Trichodesmium as an alternative to autotrophic nutrition in oligotrophic open ocean waters.
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25
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Mueller TJ, Welsh EA, Pakrasi HB, Maranas CD. Identifying Regulatory Changes to Facilitate Nitrogen Fixation in the Nondiazotroph Synechocystis sp. PCC 6803. ACS Synth Biol 2016; 5:250-8. [PMID: 26692191 DOI: 10.1021/acssynbio.5b00202] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The incorporation of biological nitrogen fixation into a nondiazotrophic photosynthetic organism provides a promising solution to the increasing fixed nitrogen demand, but is accompanied by a number of challenges for accommodating two incompatible processes within the same organism. Here we present regulatory influence networks for two cyanobacteria, Synechocystis PCC 6803 and Cyanothece ATCC 51142, and evaluate them to co-opt native transcription factors that may be used to control the nif gene cluster once it is transferred to Synechocystis. These networks were further examined to identify candidate transcription factors for other metabolic processes necessary for temporal separation of photosynthesis and nitrogen fixation, glycogen catabolism and cyanophycin synthesis. Two transcription factors native to Synechocystis, LexA and Rcp1, were identified as promising candidates for the control of the nif gene cluster and other pertinent metabolic processes, respectively. Lessons learned in the incorporation of nitrogen fixation into a nondiazotrophic prokaryote may be leveraged to further progress the incorporation of nitrogen fixation in plants.
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Affiliation(s)
- Thomas J. Mueller
- Department
of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania 16801, United States
| | - Eric A. Welsh
- Cancer
Informatics Core, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612, United States
| | - Himadri B. Pakrasi
- Department
of Energy, Environmental, and Chemical Engineering, Washington University, St. Louis, Missouri 63130, United States
- Department
of Biology, Washington University, St. Louis, Missouri 63130, United States
| | - Costas D. Maranas
- Department
of Chemical Engineering, Pennsylvania State University, University Park, Pennsylvania 16801, United States
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26
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Model-based real-time optimisation of a fed-batch cyanobacterial hydrogen production process using economic model predictive control strategy. Chem Eng Sci 2016. [DOI: 10.1016/j.ces.2015.11.043] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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27
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Adebiyi AO, Jazmin LJ, Young JD. 13 C flux analysis of cyanobacterial metabolism. PHOTOSYNTHESIS RESEARCH 2015; 126:19-32. [PMID: 25280933 DOI: 10.1007/s11120-014-0045-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Accepted: 09/22/2014] [Indexed: 06/03/2023]
Abstract
(13)C metabolic flux analysis (MFA) has made important contributions to our understanding of the physiology of model strains of E. coli and yeast, and it has been widely used to guide metabolic engineering efforts in these microorganisms. Recent advancements in (13)C MFA methodology combined with publicly available software tools are creating new opportunities to extend this approach to examine less characterized microbes. In particular, growing interest in the use of cyanobacteria as industrial hosts for photosynthetic production of biofuels and biochemicals has led to a critical need to better understand how cyanobacterial metabolic fluxes are regulated in response to changes in growth conditions or introduction of heterologous pathways. In this contribution, we review several prior studies that have applied isotopic steady-state (13)C MFA to examine heterotrophic or mixotrophic growth of cyanobacteria, as well as recent studies that have pioneered the use of isotopically nonstationary MFA (INST-MFA) to study autotrophic cultures. We also provide recommendations for the design and analysis of INST-MFA experiments in cyanobacteria, based on our previous experience and a series of simulation studies used to assess the selection of measurements and sample time points. We anticipate that this emerging knowledgebase of prior (13)C MFA studies, optimized experimental protocols, and public software tools will catalyze increasing use of (13)C MFA techniques by the cyanobacteria research community.
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Affiliation(s)
- Adeola O Adebiyi
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, 37235, USA
| | - Lara J Jazmin
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, 37235, USA
| | - Jamey D Young
- Department of Chemical and Biomolecular Engineering, Vanderbilt University, Nashville, TN, 37235, USA.
- Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN, 37235, USA.
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28
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Cyanobacterial photo-driven mixotrophic metabolism and its advantages for biosynthesis. Front Chem Sci Eng 2015. [DOI: 10.1007/s11705-015-1521-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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29
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Zhang D, Dechatiwongse P, Del Rio-Chanona EA, Maitland GC, Hellgardt K, Vassiliadis VS. Dynamic modelling of high biomass density cultivation and biohydrogen production in different scales of flat plate photobioreactors. Biotechnol Bioeng 2015; 112:2429-38. [PMID: 26041472 PMCID: PMC4975697 DOI: 10.1002/bit.25661] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2015] [Revised: 05/04/2015] [Accepted: 05/21/2015] [Indexed: 11/30/2022]
Abstract
This paper investigates the scaling‐up of cyanobacterial biomass cultivation and biohydrogen production from laboratory to industrial scale. Two main aspects are investigated and presented, which to the best of our knowledge have never been addressed, namely the construction of an accurate dynamic model to simulate cyanobacterial photo‐heterotrophic growth and biohydrogen production and the prediction of the maximum biomass and hydrogen production in different scales of photobioreactors. To achieve the current goals, experimental data obtained from a laboratory experimental setup are fitted by a dynamic model. Based on the current model, two key original findings are made in this work. First, it is found that selecting low‐chlorophyll mutants is an efficient way to increase both biomass concentration and hydrogen production particularly in a large scale photobioreactor. Second, the current work proposes that the width of industrial scale photobioreactors should not exceed 0.20 m for biomass cultivation and 0.05 m for biohydrogen production, as severe light attenuation can be induced in the reactor beyond this threshold. Biotechnol. Bioeng. 2015;112: 2429–2438. © 2015 The Authors. Biotechnology and Bioengineering Published by Wiley Peiodicals, Inc.
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Affiliation(s)
- Dongda Zhang
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge, CB2 3RA, UK
| | | | | | - Geoffrey C Maitland
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, UK
| | - Klaus Hellgardt
- Department of Chemical Engineering, Imperial College London, South Kensington Campus, London, UK
| | - Vassilios S Vassiliadis
- Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge, CB2 3RA, UK.
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30
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Dechatiwongse P, Maitland G, Hellgardt K. Demonstration of a two-stage aerobic/anaerobic chemostat for the enhanced production of hydrogen and biomass from unicellular nitrogen-fixing cyanobacterium. ALGAL RES 2015. [DOI: 10.1016/j.algal.2015.05.004] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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31
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Krishnakumar S, Gaudana SB, Digmurti MG, Viswanathan GA, Chetty M, Wangikar PP. Influence of mixotrophic growth on rhythmic oscillations in expression of metabolic pathways in diazotrophic cyanobacterium Cyanothece sp. ATCC 51142. BIORESOURCE TECHNOLOGY 2015; 188:145-152. [PMID: 25736893 DOI: 10.1016/j.biortech.2015.02.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2014] [Revised: 02/05/2015] [Accepted: 02/06/2015] [Indexed: 06/04/2023]
Abstract
This study investigates the influence of mixotrophy on physiology and metabolism by analysis of global gene expression in unicellular diazotrophic cyanobacterium Cyanothece sp. ATCC 51142 (henceforth Cyanothece 51142). It was found that Cyanothece 51142 continues to oscillate between photosynthesis and respiration in continuous light under mixotrophy with cycle time of ∼ 13 h. Mixotrophy is marked by an extended respiratory phase compared with photoautotrophy. It can be argued that glycerol provides supplementary energy for nitrogen fixation, which is derived primarily from the glycogen reserves during photoautotrophy. The genes of NDH complex, cytochrome c oxidase and ATP synthase are significantly overexpressed in mixotrophy during the day compared to autotrophy with synchronous expression of the bidirectional hydrogenase genes possibly to maintain redox balance. However, nitrogenase complex remains exclusive to nighttime metabolism concomitantly with uptake hydrogenase. This study throws light on interrelations between metabolic pathways with implications in design of hydrogen producer strains.
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Affiliation(s)
- S Krishnakumar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Sandeep B Gaudana
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Madhuri G Digmurti
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Ganesh A Viswanathan
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
| | - Madhu Chetty
- School of Information Technology, Federation University Australia, Gippsland Campus, VIC 3841, Australia
| | - Pramod P Wangikar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India; Wadhwani Research Center for Bioengineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India; DBT-Pan IIT Center for Bioenergy, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
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Kuhne S, Strieth D, Lakatos M, Muffler K, Ulber R. A new photobioreactor concept enabling the production of desiccation induced biotechnological products using terrestrial cyanobacteria. J Biotechnol 2014; 192 Pt A:28-33. [DOI: 10.1016/j.jbiotec.2014.10.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 09/24/2014] [Accepted: 10/01/2014] [Indexed: 11/29/2022]
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Dechatiwongse P, Srisamai S, Maitland G, Hellgardt K. Effects of light and temperature on the photoautotrophic growth and photoinhibition of nitrogen-fixing cyanobacterium Cyanothece sp. ATCC 51142. ALGAL RES 2014. [DOI: 10.1016/j.algal.2014.06.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Zheng Y, Quinn AH, Sriram G. Experimental evidence and isotopomer analysis of mixotrophic glucose metabolism in the marine diatom Phaeodactylum tricornutum. Microb Cell Fact 2013; 12:109. [PMID: 24228629 PMCID: PMC3842785 DOI: 10.1186/1475-2859-12-109] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2013] [Accepted: 11/06/2013] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Heterotrophic fermentation using simple sugars such as glucose is an established and cost-effective method for synthesizing bioproducts from bacteria, yeast and algae. Organisms incapable of metabolizing glucose have limited applications as cell factories, often despite many other advantageous characteristics. Therefore, there is a clear need to investigate glucose metabolism in potential cell factories. One such organism, with a unique metabolic network and a propensity to synthesize highly reduced compounds as a large fraction of its biomass, is the marine diatom Phaeodactylum tricornutum (Pt). Although Pt has been engineered to metabolize glucose, conflicting lines of evidence leave it unresolved whether Pt can natively consume glucose. RESULTS Isotope labeling experiments in which Pt was mixotrophically grown under light on 100% U-(13)C glucose and naturally abundant (~99% (12)C) dissolved inorganic carbon resulted in proteinogenic amino acids with an average 13C-enrichment of 88%, thus providing convincing evidence of glucose uptake and metabolism. The dissolved inorganic carbon was largely incorporated through anaplerotic rather than photosynthetic fixation. Furthermore, an isotope labeling experiment utilizing 1-(13)C glucose and subsequent metabolic pathway analysis indicated that (i) the alternative Entner-Doudoroff and Phosphoketolase glycolytic pathways are active during glucose metabolism, and (ii) during mixotrophic growth, serine and glycine are largely synthesized from glyoxylate through photorespiratory reactions rather than from 3-phosphoglycerate. We validated the latter result for mixotrophic growth on glycerol by performing a 2-(13)C glycerol isotope labeling experiment. Additionally, gene expression assays showed that known, native glucose transporters in Pt are largely insensitive to glucose or light, whereas the gene encoding cytosolic fructose bisphosphate aldolase 3, an important glycolytic enzyme, is overexpressed in light but insensitive to glucose. CONCLUSION We have shown that Pt can use glucose as a primary carbon source when grown in light, but cannot use glucose to sustain growth in the dark. We further analyzed the metabolic mechanisms underlying the mixotrophic metabolism of glucose and found isotopic evidence for unusual pathways active in Pt. These insights expand the envelope of Pt cultivation methods using organic substrates. We anticipate that they will guide further engineering of Pt towards sustainable production of fuels, pharmaceuticals, and platform chemicals.
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Affiliation(s)
- Yuting Zheng
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland, MD 20742, USA
| | - Andrew H Quinn
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland, MD 20742, USA
| | - Ganesh Sriram
- Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland, MD 20742, USA
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Krishnakumar S, Durai DA, Wangikar PP, Viswanathan GA. SHARP: genome-scale identification of gene-protein-reaction associations in cyanobacteria. PHOTOSYNTHESIS RESEARCH 2013; 118:181-190. [PMID: 23975204 DOI: 10.1007/s11120-013-9910-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Accepted: 08/07/2013] [Indexed: 06/02/2023]
Abstract
Genome scale metabolic model provides an overview of an organism's metabolic capability. These genome-specific metabolic reconstructions are based on identification of gene to protein to reaction (GPR) associations and, in turn, on homology with annotated genes from other organisms. Cyanobacteria are photosynthetic prokaryotes which have diverged appreciably from their nonphotosynthetic counterparts. They also show significant evolutionary divergence from plants, which are well studied for their photosynthetic apparatus. We argue that context-specific sequence and domain similarity can add to the repertoire of the GPR associations and significantly expand our view of the metabolic capability of cyanobacteria. We took an approach that combines the results of context-specific sequence-to-sequence similarity search with those of sequence-to-profile searches. We employ PSI-BLAST for the former, and CDD, Pfam, and COG for the latter. An optimization algorithm was devised to arrive at a weighting scheme to combine the different evidences with KEGG-annotated GPRs as training data. We present the algorithm in the form of software "Systematic, Homology-based Automated Re-annotation for Prokaryotes (SHARP)." We predicted 3,781 new GPR associations for the 10 prokaryotes considered of which eight are cyanobacteria species. These new GPR associations fall in several metabolic pathways and were used to annotate 7,718 gaps in the metabolic network. These new annotations led to discovery of several pathways that may be active and thereby providing new directions for metabolic engineering of these species for production of useful products. Metabolic model developed on such a reconstructed network is likely to give better phenotypic predictions.
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Affiliation(s)
- S Krishnakumar
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
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Alagesan S, Gaudana SB, Krishnakumar S, Wangikar PP. Model based optimization of high cell density cultivation of nitrogen-fixing cyanobacteria. BIORESOURCE TECHNOLOGY 2013; 148:228-233. [PMID: 24047683 DOI: 10.1016/j.biortech.2013.08.144] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 08/23/2013] [Accepted: 08/24/2013] [Indexed: 06/02/2023]
Abstract
In the present study, fed-batch cultivation of Cyanothece sp. ATCC 51142, a known hydrogen producer, was optimized for maximizing biomass production. Decline in growth of this organism in dense cultures was attributed to increased substrate consumption for maintenance and respiration, and photolimitation due to self shading. A model incorporating these aspects was developed, and by using control vector parameterization (CVP), substrate feeding recipe was optimized to achieve 12-fold higher biomass concentration. The optimization results were verified experimentally on shake flask and bioreactor. The latter resulted in greater exponential growth rate possibly by overcoming photolimitation by simulating flashing light effect. Such a strategy can be readily applied for mixotrophic cultivation of cyanobacterial cultures in the first stage followed by photoautotrophic growth at the production stage.
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Affiliation(s)
- Swathi Alagesan
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India
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Alagesan S, Gaudana SB, Sinha A, Wangikar PP. Metabolic flux analysis of Cyanothece sp. ATCC 51142 under mixotrophic conditions. PHOTOSYNTHESIS RESEARCH 2013; 118:191-198. [PMID: 23954952 DOI: 10.1007/s11120-013-9911-5] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 08/06/2013] [Indexed: 06/02/2023]
Abstract
Cyanobacteria are a group of photosynthetic prokaryotes capable of utilizing solar energy to fix atmospheric carbon dioxide to biomass. Despite several "proof of principle" studies, low product yield is an impediment in commercialization of cyanobacteria-derived biofuels. Estimation of intracellular reaction rates by (13)C metabolic flux analysis ((13)C-MFA) would be a step toward enhancing biofuel yield via metabolic engineering. We report (13)C-MFA for Cyanothece sp. ATCC 51142, a unicellular nitrogen-fixing cyanobacterium, known for enhanced hydrogen yield under mixotrophic conditions. Rates of reactions in the central carbon metabolism under nitrogen-fixing and -non-fixing conditions were estimated by monitoring the competitive incorporation of (12)C and (13)C from unlabeled CO2 and uniformly labeled glycerol, respectively, into terminal metabolites such as amino acids. The observed labeling patterns suggest mixotrophic growth under both the conditions, with a larger fraction of unlabeled carbon in nitrate-sufficient cultures asserting a greater contribution of carbon fixation by photosynthesis and an anaplerotic pathway. Indeed, flux analysis complements the higher growth observed under nitrate-sufficient conditions. On the other hand, the flux through the oxidative pentose phosphate pathway and tricarboxylic acid cycle was greater in nitrate-deficient conditions, possibly to supply the precursors and reducing equivalents needed for nitrogen fixation. In addition, an enhanced flux through fructose-6-phosphate phosphoketolase possibly suggests the organism's preferred mode under nitrogen-fixing conditions. The (13)C-MFA results complement the reported predictions by flux balance analysis and provide quantitative insight into the organism's distinct metabolic features under nitrogen-fixing and -non-fixing conditions.
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Affiliation(s)
- Swathi Alagesan
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
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Gaudana SB, Alagesan S, Chetty M, Wangikar PP. Diurnal rhythm of a unicellular diazotrophic cyanobacterium under mixotrophic conditions and elevated carbon dioxide. PHOTOSYNTHESIS RESEARCH 2013; 118:51-57. [PMID: 23881383 DOI: 10.1007/s11120-013-9888-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Accepted: 07/09/2013] [Indexed: 06/02/2023]
Abstract
Mixotrophic cultivation of cyanobacteria in wastewaters with flue gas sparging has the potential to simultaneously sequester carbon content from gaseous and aqueous streams and convert to biomass and biofuels. Therefore, it was of interest to study the effect of mixotrophy and elevated CO2 on metabolism, morphology and rhythm of gene expression under diurnal cycles. We chose a diazotrophic unicellular cyanobacterium Cyanothece sp. ATCC 51142 as a model, which is a known hydrogen producer with robust circadian rhythm. Cyanothece 51142 grows faster with nitrate and/or an additional carbon source in the growth medium and at 3 % CO2. Intracellular glycogen contents undergo diurnal oscillations with greater accumulation under mixotrophy. While glycogen is exhausted by midnight under autotrophic conditions, significant amounts remain unutilized accompanied by a prolonged upregulation of nifH gene under mixotrophy. This possibly supports nitrogen fixation for longer periods thereby leading to better growth. To gain insights into the influence of mixotrophy and elevated CO2 on circadian rhythm, transcription of core clock genes kaiA, kaiB1 and kaiC1, the input pathway, cikA, output pathway, rpaA and representatives of key metabolic pathways was analyzed. Clock genes' transcripts were lower under mixotrophy suggesting a dampening effect exerted by an external carbon source such as glycerol. Nevertheless, the genes of the clock and important metabolic pathways show diurnal oscillations in expression under mixotrophic and autotrophic growth at ambient and elevated CO2, respectively. Taken together, the results indicate segregation of light and dark associated reactions even under mixotrophy and provide important insights for further applications.
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Affiliation(s)
- Sandeep B Gaudana
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India
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Chi Z, Elloy F, Xie Y, Hu Y, Chen S. Selection of Microalgae and Cyanobacteria Strains for Bicarbonate-Based Integrated Carbon Capture and Algae Production System. Appl Biochem Biotechnol 2013; 172:447-57. [DOI: 10.1007/s12010-013-0515-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 09/15/2013] [Indexed: 10/26/2022]
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Bandyopadhyay A, Elvitigala T, Liberton M, Pakrasi HB. Variations in the rhythms of respiration and nitrogen fixation in members of the unicellular diazotrophic cyanobacterial genus Cyanothece. PLANT PHYSIOLOGY 2013; 161:1334-1346. [PMID: 23274238 PMCID: PMC3585600 DOI: 10.1104/pp.112.208231] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2012] [Accepted: 12/04/2012] [Indexed: 06/01/2023]
Abstract
In order to accommodate the physiologically incompatible processes of photosynthesis and nitrogen fixation within the same cell, unicellular nitrogen-fixing cyanobacteria have to maintain a dynamic metabolic profile in the light as well as the dark phase of a diel cycle. The transition from the photosynthetic to the nitrogen-fixing phase is marked by the onset of various biochemical and regulatory responses, which prime the intracellular environment for nitrogenase activity. Cellular respiration plays an important role during this transition, quenching the oxygen generated by photosynthesis and by providing energy necessary for the process. Although the underlying principles of nitrogen fixation predict unicellular nitrogen-fixing cyanobacteria to function in a certain way, significant variations are observed in the diazotrophic behavior of these microbes. In an effort to elucidate the underlying differences and similarities that govern the nitrogen-fixing ability of unicellular diazotrophic cyanobacteria, we analyzed six members of the genus Cyanothece. Cyanothece sp. ATCC 51142, a member of this genus, has been shown to perform efficient aerobic nitrogen fixation and hydrogen production. Our study revealed significant differences in the patterns of respiration and nitrogen fixation among the Cyanothece spp. strains that were grown under identical culture conditions, suggesting that these processes are not solely controlled by cues from the diurnal cycle but that strain-specific intracellular metabolic signals play a major role. Despite these inherent differences, the ability to perform high rates of aerobic nitrogen fixation and hydrogen production appears to be a characteristic of this genus.
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Schwarz D, Orf I, Kopka J, Hagemann M. Recent applications of metabolomics toward cyanobacteria. Metabolites 2013; 3:72-100. [PMID: 24957891 PMCID: PMC3901253 DOI: 10.3390/metabo3010072] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Revised: 01/23/2013] [Accepted: 01/23/2013] [Indexed: 11/16/2022] Open
Abstract
Our knowledge on cyanobacterial molecular biology increased tremendously by the application of the "omics" techniques. Only recently, metabolomics was applied systematically to model cyanobacteria. Metabolomics, the quantitative estimation of ideally the complete set of cellular metabolites, is particularly well suited to mirror cellular metabolism and its flexibility under diverse conditions. Traditionally, small sets of metabolites are quantified in targeted metabolome approaches. The development of separation technologies coupled to mass-spectroscopy- or nuclear-magnetic-resonance-based identification of low molecular mass molecules presently allows the profiling of hundreds of metabolites of diverse chemical nature. Metabolome analysis was applied to characterize changes in the cyanobacterial primary metabolism under diverse environmental conditions or in defined mutants. The resulting lists of metabolites and their steady state concentrations in combination with transcriptomics can be used in system biology approaches. The application of stable isotopes in fluxomics, i.e. the quantitative estimation of carbon and nitrogen fluxes through the biochemical network, has only rarely been applied to cyanobacteria, but particularly this technique will allow the making of kinetic models of cyanobacterial systems. The further application of metabolomics in the concert of other "omics" technologies will not only broaden our knowledge, but will also certainly strengthen the base for the biotechnological application of cyanobacteria.
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Affiliation(s)
- Doreen Schwarz
- Institut Biowissenschaften, Pflanzenphysiologie, Universität Rostock, Albert-Einstein-Str. 3, D-18059 Rostock, Germany.
| | - Isabel Orf
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Golm, Germany.
| | - Joachim Kopka
- Max-Planck-Institut für Molekulare Pflanzenphysiologie, Am Mühlenberg 1, 14476 Golm, Germany.
| | - Martin Hagemann
- Institut Biowissenschaften, Pflanzenphysiologie, Universität Rostock, Albert-Einstein-Str. 3, D-18059 Rostock, Germany.
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42
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Production and characterization of extracellular carbohydrate polymer from Cyanothece sp. CCY 0110. Carbohydr Polym 2013; 92:1408-15. [DOI: 10.1016/j.carbpol.2012.10.070] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 10/22/2012] [Accepted: 10/28/2012] [Indexed: 11/20/2022]
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43
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Mandalari C, Losi A, Gärtner W. Distance-tree analysis, distribution and co-presence of bilin- and flavin-binding prokaryotic photoreceptors for visible light. Photochem Photobiol Sci 2013; 12:1144-57. [DOI: 10.1039/c3pp25404f] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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44
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Proteome analyses of strains ATCC 51142 and PCC 7822 of the diazotrophic cyanobacterium Cyanothece sp. under culture conditions resulting in enhanced H₂ production. Appl Environ Microbiol 2012. [PMID: 23204418 DOI: 10.1128/aem.02864-12] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cultures of the cyanobacterial genus Cyanothece have been shown to produce high levels of biohydrogen. These strains are diazotrophic and undergo pronounced diurnal cycles when grown under N(2)-fixing conditions in light-dark cycles. We seek to better understand the way in which proteins respond to these diurnal changes, and we performed quantitative proteome analysis of Cyanothece sp. strains ATCC 51142 and PCC 7822 grown under 8 different nutritional conditions. Nitrogenase expression was limited to N(2)-fixing conditions, and in the absence of glycerol, nitrogenase gene expression was linked to the dark period. However, glycerol induced expression of nitrogenase during part of the light period, together with cytochrome c oxidase (Cox), glycogen phosphorylase (Glp), and glycolytic and pentose phosphate pathway (PPP) enzymes. This indicated that nitrogenase expression in the light was facilitated via higher levels of respiration and glycogen breakdown. Key enzymes of the Calvin cycle were inhibited in Cyanothece ATCC 51142 in the presence of glycerol under H(2)-producing conditions, suggesting a competition between these sources of carbon. However, in Cyanothece PCC 7822, the Calvin cycle still played a role in cofactor recycling during H(2) production. Our data comprise the first comprehensive profiling of proteome changes in Cyanothece PCC 7822 and allow an in-depth comparative analysis of major physiological and biochemical processes that influence H(2) production in both strains. Our results revealed many previously uncharacterized proteins that may play a role in nitrogenase activity and in other metabolic pathways and may provide suitable targets for genetic manipulation that would lead to improvement of large-scale H(2) production.
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Xiao Y, Feng X, Varman AM, He L, Yu H, Tang YJ. Kinetic Modeling and Isotopic Investigation of Isobutanol Fermentation by Two Engineered Escherichia coli Strains. Ind Eng Chem Res 2012. [DOI: 10.1021/ie202936t] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yi Xiao
- Department
of Energy, Environmental and Chemical Engineering, Washington University, One Brookings Drive, St. Louis,
Missouri 63130, United States
| | - Xueyang Feng
- Department
of Energy, Environmental and Chemical Engineering, Washington University, One Brookings Drive, St. Louis,
Missouri 63130, United States
| | - Arul M. Varman
- Department
of Energy, Environmental and Chemical Engineering, Washington University, One Brookings Drive, St. Louis,
Missouri 63130, United States
| | - Lian He
- Department
of Energy, Environmental and Chemical Engineering, Washington University, One Brookings Drive, St. Louis,
Missouri 63130, United States
| | - Huifeng Yu
- Department
of Energy, Environmental and Chemical Engineering, Washington University, One Brookings Drive, St. Louis,
Missouri 63130, United States
| | - Yinjie J. Tang
- Department
of Energy, Environmental and Chemical Engineering, Washington University, One Brookings Drive, St. Louis,
Missouri 63130, United States
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46
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Metabolic engineering of Synechocystis sp. strain PCC 6803 for isobutanol production. Appl Environ Microbiol 2012. [PMID: 23183979 DOI: 10.1128/aem.02827-12] [Citation(s) in RCA: 104] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Global warming and decreasing fossil fuel reserves have prompted great interest in the synthesis of advanced biofuels from renewable resources. In an effort to address these concerns, we performed metabolic engineering of the cyanobacterium Synechocystis sp. strain PCC 6803 to develop a strain that can synthesize isobutanol under both autotrophic and mixotrophic conditions. With the expression of two heterologous genes from the Ehrlich pathway, the engineered strain can accumulate 90 mg/liter of isobutanol from 50 mM bicarbonate in a gas-tight shaking flask. The strain does not require any inducer (i.e., isopropyl β-d-1-thiogalactopyranoside [IPTG]) or antibiotics to maintain its isobutanol production. In the presence of glucose, isobutanol synthesis is only moderately promoted (titer = 114 mg/liter). Based on isotopomer analysis, we found that, compared to the wild-type strain, the mutant significantly reduced its glucose utilization and mainly employed autotrophic metabolism for biomass growth and isobutanol production. Since isobutanol is toxic to the cells and may also be degraded photochemically by hydroxyl radicals during the cultivation process, we employed in situ removal of the isobutanol using oleyl alcohol as a solvent trap. This resulted in a final net concentration of 298 mg/liter of isobutanol under mixotrophic culture conditions.
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Tang JKH, You L, Blankenship RE, Tang YJ. Recent advances in mapping environmental microbial metabolisms through 13C isotopic fingerprints. J R Soc Interface 2012; 9:2767-80. [PMID: 22896564 DOI: 10.1098/rsif.2012.0396] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
After feeding microbes with a defined (13)C substrate, unique isotopic patterns (isotopic fingerprints) can be formed in their metabolic products. Such labelling information not only can provide novel insights into functional pathways but also can determine absolute carbon fluxes through the metabolic network via metabolic modelling approaches. This technique has been used for finding pathways that may have been mis-annotated in the past, elucidating new enzyme functions, and investigating cell metabolisms in microbial communities. In this review paper, we summarize the applications of (13)C approaches to analyse novel cell metabolisms for the past 3 years. The isotopic fingerprints (defined as unique isotopomers useful for pathway identifications) have revealed the operations of the Entner-Doudoroff pathway, the reverse tricarboxylic acid cycle, new enzymes for biosynthesis of central metabolites, diverse respiration routes in phototrophic metabolism, co-metabolism of carbon nutrients and novel CO(2) fixation pathways. This review also discusses new isotopic methods to map carbon fluxes in global metabolisms, as well as potential factors influencing the metabolic flux quantification (e.g. metabolite channelling, the isotopic purity of (13)C substrates and the isotopic effect). Although (13)C labelling is not applicable to all biological systems (e.g. microbial communities), recent studies have shown that this method has a significant value in functional characterization of poorly understood micro-organisms, including species relevant for biotechnology and human health.
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Affiliation(s)
- Joseph Kuo-Hsiang Tang
- Carlson School of Chemistry and Biochemistry, Clark University, 950 Main Street, Worcester, MA 01610, USA
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Vu TT, Stolyar SM, Pinchuk GE, Hill EA, Kucek LA, Brown RN, Lipton MS, Osterman A, Fredrickson JK, Konopka AE, Beliaev AS, Reed JL. Genome-scale modeling of light-driven reductant partitioning and carbon fluxes in diazotrophic unicellular cyanobacterium Cyanothece sp. ATCC 51142. PLoS Comput Biol 2012; 8:e1002460. [PMID: 22529767 PMCID: PMC3329150 DOI: 10.1371/journal.pcbi.1002460] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Accepted: 02/20/2012] [Indexed: 11/22/2022] Open
Abstract
Genome-scale metabolic models have proven useful for answering fundamental questions about metabolic capabilities of a variety of microorganisms, as well as informing their metabolic engineering. However, only a few models are available for oxygenic photosynthetic microorganisms, particularly in cyanobacteria in which photosynthetic and respiratory electron transport chains (ETC) share components. We addressed the complexity of cyanobacterial ETC by developing a genome-scale model for the diazotrophic cyanobacterium, Cyanothece sp. ATCC 51142. The resulting metabolic reconstruction, iCce806, consists of 806 genes associated with 667 metabolic reactions and includes a detailed representation of the ETC and a biomass equation based on experimental measurements. Both computational and experimental approaches were used to investigate light-driven metabolism in Cyanothece sp. ATCC 51142, with a particular focus on reductant production and partitioning within the ETC. The simulation results suggest that growth and metabolic flux distributions are substantially impacted by the relative amounts of light going into the individual photosystems. When growth is limited by the flux through photosystem I, terminal respiratory oxidases are predicted to be an important mechanism for removing excess reductant. Similarly, under photosystem II flux limitation, excess electron carriers must be removed via cyclic electron transport. Furthermore, in silico calculations were in good quantitative agreement with the measured growth rates whereas predictions of reaction usage were qualitatively consistent with protein and mRNA expression data, which we used to further improve the resolution of intracellular flux values. Cyanobacteria have been promoted as platforms for biofuel production due to their useful physiological properties such as photosynthesis, relatively rapid growth rates, ability to accumulate high amounts of intracellular compounds and tolerance to extreme environments. However, development of a computational model is an important step to synthesize biochemical, physiological and regulatory understanding of photoautotrophic metabolism (either qualitatively or quantitatively) at a systems level, to make metabolic engineering of these organisms tractable. When integrated with other genome-scale data (e.g., expression data), numerical simulations can provide experimentally testable predictions of carbon fluxes and reductant partitioning to different biosynthetic pathways and macromolecular synthesis. This work is the first to computationally explore the interactions between components of photosynthetic and respiratory systems in detail. In silico predictions obtained from model analysis provided insights into the effects of light quantity and quality upon fluxes through electron transport pathways, alternative pathways for reductant consumption and carbon metabolism. The model will not only serve as a platform to develop genome-scale metabolic models for other cyanobacteria, but also as an engineering tool for manipulation of photosynthetic microorganisms to improve biofuel production.
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Affiliation(s)
- Trang T. Vu
- Department of Chemical and Biological Engineering, University of Wisconsin- Madison, Madison, Wisconsin, United States of America
| | - Sergey M. Stolyar
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Grigoriy E. Pinchuk
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Eric A. Hill
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Leo A. Kucek
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Roslyn N. Brown
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Mary S. Lipton
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Andrei Osterman
- Burnham Institute for Medical Research, La Jolla, California, United States of America
| | - Jim K. Fredrickson
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Allan E. Konopka
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
| | - Alexander S. Beliaev
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, Washington, United States of America
- * E-mail: (ASB); (JLR)
| | - Jennifer L. Reed
- Department of Chemical and Biological Engineering, University of Wisconsin- Madison, Madison, Wisconsin, United States of America
- * E-mail: (ASB); (JLR)
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Feng X, Xu Y, Chen Y, Tang YJ. Integrating flux balance analysis into kinetic models to decipher the dynamic metabolism of Shewanella oneidensis MR-1. PLoS Comput Biol 2012; 8:e1002376. [PMID: 22319437 PMCID: PMC3271021 DOI: 10.1371/journal.pcbi.1002376] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Accepted: 12/20/2011] [Indexed: 11/22/2022] Open
Abstract
Shewanella oneidensis MR-1 sequentially utilizes lactate and its waste products (pyruvate and acetate) during batch culture. To decipher MR-1 metabolism, we integrated genome-scale flux balance analysis (FBA) into a multiple-substrate Monod model to perform the dynamic flux balance analysis (dFBA). The dFBA employed a static optimization approach (SOA) by dividing the batch time into small intervals (i.e., ∼400 mini-FBAs), then the Monod model provided time-dependent inflow/outflow fluxes to constrain the mini-FBAs to profile the pseudo-steady-state fluxes in each time interval. The mini-FBAs used a dual-objective function (a weighted combination of "maximizing growth rate" and "minimizing overall flux") to capture trade-offs between optimal growth and minimal enzyme usage. By fitting the experimental data, a bi-level optimization of dFBA revealed that the optimal weight in the dual-objective function was time-dependent: the objective function was constant in the early growth stage, while the functional weight of minimal enzyme usage increased significantly when lactate became scarce. The dFBA profiled biologically meaningful dynamic MR-1 metabolisms: 1. the oxidative TCA cycle fluxes increased initially and then decreased in the late growth stage; 2. fluxes in the pentose phosphate pathway and gluconeogenesis were stable in the exponential growth period; and 3. the glyoxylate shunt was up-regulated when acetate became the main carbon source for MR-1 growth.
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Affiliation(s)
- Xueyang Feng
- Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, Missouri, United States of America
| | - You Xu
- Department of Computer Science and Engineering, Washington University, St. Louis, Missouri, United States of America
| | - Yixin Chen
- Department of Computer Science and Engineering, Washington University, St. Louis, Missouri, United States of America
| | - Yinjie J. Tang
- Department of Energy, Environmental and Chemical Engineering, Washington University, St. Louis, Missouri, United States of America
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You L, Page L, Feng X, Berla B, Pakrasi HB, Tang YJ. Metabolic pathway confirmation and discovery through (13)C-labeling of proteinogenic amino acids. J Vis Exp 2012:e3583. [PMID: 22314852 PMCID: PMC3462576 DOI: 10.3791/3583] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Microbes have complex metabolic pathways that can be investigated using biochemistry and functional genomics methods. One important technique to examine cell central metabolism and discover new enzymes is (13)C-assisted metabolism analysis 1. This technique is based on isotopic labeling, whereby microbes are fed with a (13)C labeled substrates. By tracing the atom transition paths between metabolites in the biochemical network, we can determine functional pathways and discover new enzymes. As a complementary method to transcriptomics and proteomics, approaches for isotopomer-assisted analysis of metabolic pathways contain three major steps (2). First, we grow cells with (13)C labeled substrates. In this step, the composition of the medium and the selection of labeled substrates are two key factors. To avoid measurement noises from non-labeled carbon in nutrient supplements, a minimal medium with a sole carbon source is required. Further, the choice of a labeled substrate is based on how effectively it will elucidate the pathway being analyzed. Because novel enzymes often involve different reaction stereochemistry or intermediate products, in general, singly labeled carbon substrates are more informative for detection of novel pathways than uniformly labeled ones for detection of novel pathways(3, 4). Second, we analyze amino acid labeling patterns using GC-MS. Amino acids are abundant in protein and thus can be obtained from biomass hydrolysis. Amino acids can be derivatized by N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (TBDMS) before GC separation. TBDMS derivatized amino acids can be fragmented by MS and result in different arrays of fragments. Based on the mass to charge (m/z) ratio of fragmented and unfragmented amino acids, we can deduce the possible labeled patterns of the central metabolites that are precursors of the amino acids. Third, we trace 13C carbon transitions in the proposed pathways and, based on the isotopomer data, confirm whether these pathways are active (2). Measurement of amino acids provides isotopic labeling information about eight crucial precursor metabolites in the central metabolism. These metabolic key nodes can reflect the functions of associated central pathways. (13)C-assisted metabolism analysis via proteinogenic amino acids can be widely used for functional characterization of poorly-characterized microbial metabolism(1). In this protocol, we will use Cyanothece 51142 as the model strain to demonstrate the use of labeled carbon substrates for discovering new enzymatic functions.
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Affiliation(s)
- Le You
- Department of Energy, Environmental and Chemical Engineering, Washington University, USA
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