| 1. |
- Ferreira, Daniela, et al.
(författare)
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Transcription and regulation of the hydrogenase(s) accessory genes, hypFCDEAB, in the cyanobacterium Lyngbya majuscula CCAP 1446/4
- 2007
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Ingår i: Archives of Microbiology. - : Springer Science and Business Media LLC. - 0302-8933 .- 1432-072X. ; 188:6, s. 609-617
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Tidskriftsartikel (refereegranskat)abstract
- Lyngbya majuscula CCAP 1446/4 is a filamentous cyanobacterium possessing both an uptake and a bi-directional hydrogenase. The presence of a single copy of the hyp operon in the cyanobacterial genomes suggests that these accessory genes might be responsible for the maturation of both hydrogenases. We investigated the concomitant transcription of hypFCDEAB with the hydrogenases structural genes-hup and hox. RT-PCRs performed with L. majuscula cells grown under different physiological conditions showed a substantial decrease in the relative amount of hupL transcript under non-N-2-fixing conditions. In contrast, no significant differences were observed for the transcript levels of hypFCDEAB in all conditions tested, while minor fluctuations could be discerned for hoxH. Previously, it was demonstrated that the transcriptional regulators NtcA and LexA interact with the promoter regions of hup and hox, respectively, and that putative binding sites for both proteins are present in the hyp promoter of L. majuscula. Therefore, a putative involvement of NtcA and LexA in the regulation of the hyp transcription was investigated. Electrophoretic mobility shift assays resulted in NtcA or LexA-bound retarded fragments, suggesting the involvement of these proteins in the transcriptional regulation of hypFCDEAB.
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| 2. |
- Lindblad, Peter, et al.
(författare)
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CyanoFactory, a European consortium to develop technologies needed to advance cyanobacteria as chassis for production of chemicals and fuels
- 2019
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Ingår i: Algal Research. - : Elsevier. - 2211-9264. ; 41
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Forskningsöversikt (refereegranskat)abstract
- CyanoFactory, Design, construction and demonstration of solar biofuel production using novel (photo) synthetic cell factories, was an R&D project developed in response to the European Commission FP7-ENERGY-2012-1 call "Future Emerging Technologies" and the need for significant advances in both new science and technologies to convert solar energy into a fuel. CyanoFactory was an example of "purpose driven" research and development with identified scientific goals and creation of new technologies. The present overview highlights significant outcomes of the project, three years after its successful completion. The scientific progress of CyanoFactory involved: (i) development of a ToolBox for cyanobacterial synthetic biology; (ii) construction of DataWarehouse/Bioinformatics web-based capacities and functions; (iii) improvement of chassis growth, functionality and robustness; (iv) introduction of custom designed genetic constructs into cyanobacteria, (v) improvement of photosynthetic efficiency towards hydrogen production; (vi) biosafety mechanisms; (vii) analyses of the designed cyanobacterial cells to identify bottlenecks with suggestions on further improvements; (viii) metabolic modelling of engineered cells; (ix) development of an efficient laboratory scale photobioreactor unit; and (x) the assembly and experimental performance assessment of a larger (1350 L) outdoor flat panel photobioreactor system during two seasons. CyanoFactory - Custom design and purpose construction of microbial cells for the production of desired products using synthetic biology - aimed to go beyond conventional paths to pursue innovative and high impact goals. CyanoFactory brought together ten leading European partners (universities, research organizations and enterprises) with a common goal - to develop the future technologies in Synthetic biology and Advanced photobioreactors.
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| 3. |
- Santos, Marina, et al.
(författare)
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CRISPRi as a Tool to Repress Multiple Copies of Extracellular Polymeric Substances (EPS)-Related Genes in the Cyanobacterium Synechocystis sp. PCC 6803
- 2021
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Ingår i: Life. - : MDPI AG. - 2075-1729. ; 11:11
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Tidskriftsartikel (refereegranskat)abstract
- The use of the versatile cyanobacterial extracellular polymeric substances (EPS) for biotechnological/biomedical applications implies an extensive knowledge of their biosynthetic pathways to improve/control polymer production yields and characteristics. The multiple copies of EPS-related genes, scattered throughout cyanobacterial genomes, adds another layer of complexity, making these studies challenging and time-consuming. Usually, this issue would be tackled by generating deletion mutants, a process that in cyanobacteria is also hindered by the polyploidy. Thus, the use of the CRISPRi multiplex system constitutes an efficient approach to addressing this redundancy. Here, three putative Synechocystis sp. PCC 6803 kpsM homologues (slr0977, slr2107, and sll0574) were repressed using this methodology. The characterization of the 3-sgRNA mutant in terms of fitness/growth and total carbohydrates, released and capsular polysaccharides, and its comparison with previously generated single knockout mutants pointed towards Slr0977 being the key KpsM player in Synechocystis EPS production. This work validates CRISPRi as a powerful tool to unravel cyanobacterial complex EPS biosynthetic pathways expediting this type of studies.
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| 4. |
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| 5. |
- Schütz, Karin, et al.
(författare)
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Cyanobacterial H2 production - a comparative analysis
- 2004
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Ingår i: Planta. ; 218, s. 350-359
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Tidskriftsartikel (refereegranskat)abstract
- Several unicellular and filamentous, nitrogen-fixing and non-nitrogen-fixing cyanobacterial strains have been investigated on the molecular and the physiological level in order to find the most efficient organisms for photobiological hydrogen production. These strains were screened for the presence or absence of hup and hox genes, and it was shown that they have different sets of genes involved in H2 evolution. The uptake hydrogenase was identified in all N2-fixing cyanobacteria, and some of these strains also contained the bidirectional hydrogenase, whereas the non-nitrogen fixing strains only possessed the bidirectional enzyme. In N2-fixing strains, hydrogen was mainly produced by the nitrogenase as a by-product during the reduction of atmospheric nitrogen to ammonia. Therefore, hydrogen production was investigated both under non-nitogen-fixing conditions and under nitrogen limitation. It was shown that the hydrogen uptake activity is linked tothe nitrogenase activity, wheras the hydrogen evolution activity of the bidirectional hydrogenase is not dependent or even reelated to diazotrophic growth consditions. With regard to large-scale hydrogen evolution by N2-fixing cyanobacteria, hydrogen uptake-decicient mutants have to be used because of their inability to re-oxidize the hydrogen produced by the nitrogenase. On the other hand, fermentative H2 production by directional hydrogenase should also be taken into account inn further investigations of biological hydrogen production.
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| 6. |
- Tamagnini, Paula, et al.
(författare)
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Cyanobacterial hydrogenases : diversity, regulation and applications
- 2007
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Ingår i: FEMS Microbiology Reviews. - : Oxford University Press (OUP). - 0168-6445 .- 1574-6976. ; 31:6, s. 692-720
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Forskningsöversikt (refereegranskat)abstract
- Cyanobacteria may possess two distinct nickel-iron (NiFe)-hydrogenases: an uptake enzyme found in N2-fixing strains, and a bidirectional one present in both non-N2-fixing and N2-fixing strains. The uptake hydrogenase (encoded by hupSL) catalyzes the consumption of the H2 produced during N2 fixation, while the bidirectional enzyme (hoxEFUYH) probably plays a role in fermn. and/or acts as an electron valve during photosynthesis. HupSL constitute a transcriptional unit, and are essentially transcribed under N2-fixing conditions. The bidirectional hydrogenase consists of a hydrogenase and a diaphorase part, and the corresponding five hox genes are not always clustered or cotranscribed. The biosynthesis/maturation of NiFe-hydrogenases is highly complex, requiring several core proteins. In cyanobacteria, the genes that are thought to affect hydrogenases pleiotropically (hyp), as well as the genes presumably encoding the hydrogenase-specific endopeptidases (hupW and hoxW) have been identified and characterized. Furthermore, NtcA and LexA have been implicated in the transcriptional regulation of the uptake and the bidirectional enzyme resp. Recently, the phylogenetic origin of cyanobacterial and algal hydrogenases was analyzed, and it was proposed that the current distribution in cyanobacteria reflects a differential loss of genes according to their ecol. needs or constraints. In addn., the possibilities and challenges of cyanobacterial-based H2 prodn. are addressed.
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| 7. |
- Wegelius, Adam, et al.
(författare)
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Generation of a functional, semisynthetic [FeFe]-hydrogenase in a photosynthetic microorganism
- 2018
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Ingår i: Energy & Environmental Science. - : Royal Society of Chemistry (RSC). - 1754-5692 .- 1754-5706. ; 11:11, s. 3163-3167
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Tidskriftsartikel (refereegranskat)abstract
- [FeFe]-Hydrogenases are hydrogen producing metalloenzymes with excellent catalytic capacities, highly relevant in the context of a future hydrogen economy. Here we demonstrate the synthetic activation of a heterologously expressed [FeFe]-hydrogenase in living cells of Synechocystis PCC 6803, a photoautotrophic microbial chassis with high potential for biotechnological energy applications. H-2-Evolution assays clearly show that the non-native, semi-synthetic enzyme links to the native metabolism in living cells.
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