| 1. |
- Agervald, Åsa, et al.
(författare)
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The CyAbrB transcription factor CalA regulates the iron superoxide dismutase in Nostoc sp. strain PCC 7120
- 2010
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Ingår i: Environmental Microbiology. - : Wiley. - 1462-2912 .- 1462-2920. ; 12:10, s. 2826-2837
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Tidskriftsartikel (refereegranskat)abstract
- P>In the present investigation the results of induced over-production of the CyAbrB transcription factor CalA (Cyanobacterial AbrB-like, annotated as Alr0946) in the cyanobacterium Nostoc sp. PCC 7120 were analysed. The CalA overexpression strain showed a bleaching phenotype with lower growth rate and truncated filaments 2 days after induction of overexpression. The phenotype was even more pronounced when illumination was increased from 35 to 125 mu mol m-2 s-1. Using gel-based quantitative proteomics, the induced overexpression of CalA was shown to downregulate the abundance of FeSOD, one of two types of superoxide dismutases in Nostoc sp. PCC 7120. The change in protein abundance was also accompanied by lower transcript as well as activity levels. Purified recombinant CalA from Nostoc sp. PCC 7120 was shown to interact with the promoter region of alr2938, encoding FeSOD, indicating a transcriptional regulation of FeSOD by CalA. The bleaching phenotype is in line with a decreased tolerance against oxidative stress and indicates that CalA is involved in regulation of cellular responses in which FeSOD has an important and specific function in the filamentous cyanobacterium Nostoc sp. PCC 7120.
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| 2. |
- Baebprasert, Wipawee, et al.
(författare)
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Increased H(2) production in the cyanobacterium Synechocystis sp strain PCC 6803 by redirecting the electron supply via genetic engineering of the nitrate assimilation pathway
- 2011
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Ingår i: Metabolic engineering. - : Elsevier BV. - 1096-7176 .- 1096-7184. ; 13:5, s. 610-616
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Tidskriftsartikel (refereegranskat)abstract
- The unicellular cyanobacterium Synechocystis sp. strain PCC 6803 contains a single bidirectional NiFe-Hox-hydrogenase, which evolves hydrogen under certain environmental conditions. The nitrate assimilation pathway is a potential competing pathway that may reduce the electron flow to the hydrogenase and thereby limit hydrogen production. To improve H(2) production, the nitrate assimilation pathway was disrupted by genetic engineering to redirect the electron flow towards the Hox-hydrogenase. Mutant strains disrupted in either nitrate reductase (Delta narB) or nitrite reductase (Delta nirA) or both nitrate reductase and nitrite reductase (Delta narB:Delta nirA) were constructed and tested for their ability to produce hydrogen. H(2) production and Hox-hydrogenase activities in all the mutant strains were higher than those in wild-type. Highest H(2) production was observed in the Delta narB:Delta nirA strain. Small changes were observed for Hox-hydrogenase enzyme activities and only minor changes in transcript levels of hoxH and hoxY were not correlated with H(2) production. The results suggest that the high rate of H(2) production observed in the Delta narB:Delta nirA strain of the cyanobacterium Synechocystis sp. strain PCC 6803 is the result of redirecting the electron supply from the nitrate assimilation pathway, through genetic engineering, towards the Hox-hydrogenase.
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| 3. |
- Baebprasert, Wipawee, et al.
(författare)
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Na(+)-stimulated nitrate uptake with increased activity under osmotic upshift in Synechocystis sp strain PCC 6803
- 2011
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Ingår i: World Journal of Microbiology & Biotechnology. - : Springer Science and Business Media LLC. - 0959-3993 .- 1573-0972. ; 27:10, s. 2467-2473
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Tidskriftsartikel (refereegranskat)abstract
- In the non-diazotrophic cyanobacterium Synechocystis sp. strain PCC 6803, an osmolality of 30 and 40 mosmol/kg sorbitol and NaCl resulted in 3.5- and 4.5-fold increase of nitrate uptake, respectively. The NaCl-stimulated uptake was abolished by treatment with chloramphenicol. At 25 mosmol/kg or higher, NaCl induced higher nitrate uptake than sorbitol suggesting an ionic effect of Na(+). The nitrate uptake in Synechocystis showed K (s) and V (max) values of 46 mu M and 1.37 mu mol/min/mg Chl, respectively. Mutants disrupted in nitrate and nitrite reductase exhibited a decreased nitrate uptake. Ammonium, chlorate, and dl-glyceraldehyde caused a reduction of nitrate uptake. Dark treatment caused a drastic reduction of uptake by 70% suggesting an energy-dependent system. Nitrate transport was sensitive to various metabolic inhibitors including those dissipating proton gradients and membrane potential. The results suggest that nitrate uptake in Synechocystis is stimulated by Na(+) ions and requires energy provided by the functioning electron transport chain.
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| 4. |
- Baebprasert, Wipawee, et al.
(författare)
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Response of H-2 production and Hox-hydrogenase activity to external factors in the unicellular cyanobacterium Synechocystis sp strain PCC 6803
- 2010
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 35:13, s. 6611-6616
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Tidskriftsartikel (refereegranskat)abstract
- The effects of external factors on both H-2 production and bidirectional Hox-hydrogenase activity were examined in the non-N-2-fixing cyanobacterium Synechocystis PCC 6803. Exogenous glucose and increased osmolality both enhanced H-2 production with optimal production observed at 0.4% and 20 mosmol kg(-1), respectively. Anaerobic condition for 24 h induced significant higher H(2)ase activity with cells in BC11(0) showing highest activities. Increasing the pH resulted in an increased Hox-hydrogenase activity with an optimum at pH 7.5. The Hox-hydrogenase activity gradually increased with increasing temperature from 30 degrees C to 60 degrees C with the highest activity observed at 70 degrees C. A low concentration at 100 mu M of either DTT or beta-mercaptoethanol resulted in a minor stimulation of H-2 production. beta-Mercaptoethanol added to nitrogen- and sulfur-deprived cells stimulated H-2 production significantly. The highest Hox-hydrogenase activity was observed in cells in BG11(0)-S-deprived condition and 750 mu M beta-mercaptoethanol measured at a temperature of 70 degrees C; 14.32 mu mol H-2 mg chl alpha(-1) min(-1).
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| 5. |
- Eungrasamee, Kamonchanock, et al.
(författare)
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Improved lipid production via fatty acid biosynthesis and free fatty acid recycling in engineered Synechocystis sp. PCC 6803
- 2019
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Ingår i: Biotechnology for Biofuels. - : Springer Science and Business Media LLC. - 1754-6834. ; 12, s. 1-13
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundCyanobacteria are potential sources for third generation biofuels. Their capacity for biofuel production has been widely improved using metabolically engineered strains. In this study, we employed metabolic engineering design with target genes involved in selected processes including the fatty acid synthesis (a cassette of accD, accA, accC and accB encoding acetyl-CoA carboxylase, ACC), phospholipid hydrolysis (lipA encoding lipase A), alkane synthesis (aar encoding acyl-ACP reductase, AAR), and recycling of free fatty acid (FFA) (aas encoding acyl-acyl carrier protein synthetase, AAS) in the unicellular cyanobacterium Synechocystis sp. PCC 6803.ResultsTo enhance lipid production, engineered strains were successfully obtained including an aas-overexpressing strain (OXAas), an aas-overexpressing strain with aar knockout (OXAas/KOAar), and an accDACB-overexpressing strain with lipA knockout (OXAccDACB/KOLipA). All engineered strains grew slightly slower than wild-type (WT), as well as with reduced levels of intracellular pigment levels of chlorophyll a and carotenoids. A higher lipid content was noted in all the engineered strains compared to WT cells, especially in OXAas, with maximal content and production rate of 34.5% w/DCW and 41.4mg/L/day, respectively, during growth phase at day 4. The OXAccDACB/KOLipA strain, with an impediment of phospholipid hydrolysis to FFA, also showed a similarly high content of total lipid of about 32.5% w/DCW but a lower production rate of 31.5mg/L/day due to a reduced cell growth. The knockout interruptions generated, upon a downstream flow from intermediate fatty acyl-ACP, an induced unsaturated lipid production as observed in OXAas/KOAar and OXAccDACB/KOLipA strains with 5.4% and 3.1% w/DCW, respectively.ConclusionsAmong the three metabolically engineered Synechocystis strains, the OXAas with enhanced free fatty acid recycling had the highest efficiency to increase lipid production.
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| 6. |
- Eungrasamee, Kamonchanock, et al.
(författare)
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Overexpression of lipA or glpD_RuBisCO in the Synechocystis sp. PCC 6803 Mutant Lacking the Aas Gene Enhances Free Fatty-Acid Secretion and Intracellular Lipid Accumulation
- 2021
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Ingår i: International Journal of Molecular Sciences. - : MDPI. - 1661-6596 .- 1422-0067. ; 22:21
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Tidskriftsartikel (refereegranskat)abstract
- Although engineered cyanobacteria for the production of lipids and fatty acids (FAs) are intelligently used as sustainable biofuel resources, intracellularly overproduced FAs disturb cellular homeostasis and eventually generate lethal toxicity. In order to improve their production by enhancing FFAs secretion into a medium, we constructed three engineered Synechocystis 6803 strains including KA (a mutant lacking the aas gene), KAOL (KA overexpressing lipA, encoding lipase A in membrane lipid hydrolysis), and KAOGR (KA overexpressing quadruple glpD/rbcLXS, related to the CBB cycle). Certain contents of intracellular lipids and secreted FFAs of all engineered strains were higher than those of the wild type. Remarkably, the KAOL strain attained the highest level of secreted FFAs by about 21.9%w/DCW at day 5 of normal BG11 cultivation, with a higher growth rate and shorter doubling time. TEM images provided crucial evidence on the morphological changes of the KAOL strain, which accumulated abundant droplets on regions of thylakoid membranes throughout the cell when compared with wild type. On the other hand, BG11-N condition significantly induced contents of both intracellular lipids and secreted FFAs of the KAOL strain up to 37.2 and 24.5%w/DCW, respectively, within 5 days. Then, for the first time, we shone a spotlight onto the overexpression of lipA in the aas mutant of Synechocystis as another potential strategy to achieve higher FFAs secretion with sustainable growth.
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| 7. |
- Eungrasamee, Kamonchanock, et al.
(författare)
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Synechocystis sp. PCC 6803 overexpressing genes involved in CBB cycle and free fatty acid cycling enhances the significant levels of intracellular lipids and secreted free fatty acids
- 2020
-
Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 10:1
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Tidskriftsartikel (refereegranskat)abstract
- The integrative aspect on carbon fixation and lipid production is firstly implemented in cyanobacterium Synechocystis sp. PCC 6803 using metabolic engineering approach. Genes related to Calvin-Benson-Bassham (CBB) cycle including rbcLXS and glpD and free fatty acid recycling including aas encoding acyl-ACP synthetase were practically manipulated in single, double and triple overexpressions via single homologous recombination. The significantly increased growth rate and intracellular pigment contents were evident in glpD-overexpressing (OG) strain among all strains studied under normal growth condition. The triple aas_glpD_rbcLXS-overexpressing (OAGR) strain notably gave the highest contents of both intracellular lipids and extracellular free fatty acids (FFAs) of about 35.9 and 9.6% w/DCW, respectively, when compared to other strains at day 5 of cultivation. However, the highest intracellular lipid titer and production rate were observed in OA strain at day 5 (228.7mg/L and 45.7mg/L/day, respectively) and OG strain at day 10 (358.3mg/L and 35.8mg/L/day, respectively) due to their higher growth. For fatty acid (FA) compositions, the main saturated fatty acid of palmitic acid (C16:0) was dominantly found in both intracellular lipid and secreted FFAs fractions. Notably, intracellular FA proportion of myristic acid (C14:0) was induced in all engineered strains whereas the increase of stearic acid (C18:0) composition was found in extracellular FFAs fraction. Altogether, these overexpressing strains efficiently produced higher lipid production via homeostasis balance on both its lipid synthesis and FFAs secretion.
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| 8. |
- Khetkorn, Wanthanee, et al.
(författare)
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Enhanced biohydrogen production by the N-2-fixing cyanobacterium Anabaena siamensis strain TISTR 8012
- 2010
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 35:23, s. 12767-12776
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of hydrogen production depends on several factors We focused on external conditions leading to enhanced hydrogen production when using the N-2 fixing cyanobacterium Anabaena siamensis TISTR 8012 a novel strain isolated from a rice paddy field in Thailand In this study we controlled key factors affecting hydrogen production such as cell age light intensity time of light incubation and source of carbon Our results showed an enhanced hydrogen production when cells at log phase were adapted under N-2 fixing condition using 0 5% fructose as carbon source and a continuous illumination of 200 mu E m(-2) s(-1) for 12 h under anaerobic incubation The maximum hydrogen production rate was 32 mu mol H-2 mg chl a(-1) h(-1) This rate was higher than that observed in the model organisms Anabaena PCC 7120 Nostoc punctiforme ATCC 29133 and Synechocystis PCC 6803 This higher production was likely caused by a higher nitrogenase activity since we observed an upregulation of nifD The production did not increase after 12 h which was probably due to an increased activity of the uptake hydrogenase as evidenced by an increased hupL transcript level Interestingly a proper adjustment of light conditions such as intensity and duration is important to minimize both the photodamage of the cells and the uptake hydrogenase activity Our results indicate that A siamensis TISTR 8012 has a high potential for hydrogen production with the ability to utilize sugars as substrate to produce hydrogen.
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| 9. |
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| 10. |
- Khetkorn, Wanthanee, et al.
(författare)
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Enhancement of poly-3-hydroxybutyrate production in Synechocystis sp PCC 6803 by overexpression of its native biosynthetic genes
- 2016
-
Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 214, s. 761-768
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Tidskriftsartikel (refereegranskat)abstract
- Synechocystis sp. PCC 6803 strains overexpressing pha genes were constructed and characterized for poly-3- hydroxybutyrate (PHB) production. These pha overexpressing strains showed slightly reduced growth rates. Under N-deprived condition, the strains overexpressing (OE) phaAB, phaEC and phaABEC showed significantly higher PHB contents than the wild type. The maximum PHB content, a 2.6-fold increase producing 26% PHB (dcw), was observed in OE phaAB cells grown for 9 days in N-deprived medium. Under this condition, these OE phaAB cells increased PHB production to 35% PHB (dcw) upon addition of 0.4% (w/v) acetate. Higher PHB granules in OE phaAB cells were clearly visualized by both Nile red staining and TEM imaging. All OE strains under N-deficient condition had increased glgX transcript levels. Overall results demonstrate an enhanced PHB production in Synechocystis cells overexpressing pha genes, particularly phaA and phaB, when grown in N-deprived medium containing 0.4% (w/v) acetate.
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| 11. |
- Khetkorn, Wanthanee, et al.
(författare)
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Microalgal hydrogen production : A review
- 2017
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 243, s. 1194-1206
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Forskningsöversikt (refereegranskat)abstract
- Bio-hydrogen from microalgae including cyanobacteria has attracted commercial awareness due to its potential as an alternative, reliable and renewable energy source. Photosynthetic hydrogen production from microalgae can be interesting and promising options for clean energy. Advances in hydrogen-fuel-cell technology may attest an eco-friendly way of biofuel production, since, the use of H-2 to generate electricity releases only water as a by-product. Progress in genetic/metabolic engineering may significantly enhance the photobiological hydrogen production from microalgae. Manipulation of competing metabolic pathways by modulating the certain key enzymes such as hydrogenase and nitrogenase may enhance the evolution of H-2 from photoautotrophic cells. Moreover, biological H-2 production at low operating costs is requisite for economic viability. Several photobioreactors have been developed for large-scale biomass and hydrogen production. This review highlights the recent technological progress, enzymes involved and genetic as well as metabolic engineering approaches towards sustainable hydrogen production from microalgae.
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| 12. |
- Khetkorn, Wanthanee, et al.
(författare)
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Redirecting the electron flow towards the nitrogenase and bidirectional Hox-hydrogenase by using specific inhibitors results in enhanced H-2 production in the cyanobacterium Anabaena siamensis TISTR 8012
- 2012
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 118, s. 265-271
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Tidskriftsartikel (refereegranskat)abstract
- The inhibition of competitive metabolic pathways by various inhibitors in order to redirect electron flow towards nitrogenase and bidirectional Hox-hydrogenase was investigated in Anabaena siamensis TISTR 8012. Cells grown in BG11(0) supplemented with KCN, rotenone, DCMU, and DL-glyceraldehyde under light condition for 24 h showed enhanced H-2 production. Cells grown in BG11 medium showed only marginal H-2 production and its production was hardly increased by the inhibitors tested. H-2 production with either 20 mM KCN or 50 mu M DCMU in BG11(0) medium was 22 mu mol H-2 mg chl a(-1) h(-1), threefold higher than the control. The increased H-2 production caused by inhibitors was consistent with the increase in the respective Hox-hydrogenase activities and nifD transcript levels, as well as the decrease in hupL transcript levels. The results suggested that interruption of metabolic pathways essential for growth could redirect electrons flow towards nitrogenase and bidirectional Hox-hydrogenase resulting in increased H-2 production. (C) 2012 Elsevier Ltd. All rights reserved.
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| 13. |
- Khetorn, Wanthanee, et al.
(författare)
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Metabolic and genetic engineering of cyanobacteria for enhanced hydrogen production
- 2013
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Ingår i: Biofuels. - : Informa UK Limited. - 1759-7269 .- 1759-7277. ; 4:5, s. 535-561
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Tidskriftsartikel (refereegranskat)abstract
- There is an urgent need to develop sustainable solutions to convert solar energy into energy carriers used in the society. In addition to solar cells generating electricity, there are several options to generate solar fuels with molecular hydrogen (H2) being an interesting and promising option. Native and engineered cyanobacteria have been used as model systems to examine, develop and demonstrate photobiological hydrogen production. In the present review we present and discuss recent progress with respect to (i) native biological systems to generate hydrogen, (ii) metabolic modulations, and (iii) genetic engineering of metabolic pathways, as well as the (iv) introduction of custom-designed, non-native enzymes and complexes for enhanced hydrogen production in cyanobacteria. In conclusion, metabolic and genetic engineering of native cyanobacterial hydrogen metabolism can significantly increase the hydrogen production, and introduction of custom-designed non-native capacities open up new possibilities to further enhance cyanobacterial based hydrogen production.
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| 14. |
- Maneeruttanarungroj, Cherdsak, et al.
(författare)
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A newly isolated green alga, Tetraspora sp. CU2551, from Thailand with efficient hydrogen production
- 2010
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 35:24, s. 13193-13199
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Tidskriftsartikel (refereegranskat)abstract
- A novel unicellular hydrogen-producing green alga was isolated from fresh water pond in Pathumthani province, Thailand. Under light microscope, this alga was identified as belonging to the genus Tetraspora. Phylogenetic analysis of 18S rRNA sequence revealed that the green alga, identified as Tetraspora sp. CU2551, is closely related to other unicellular green algal species. Tetraspora sp. CU2551 had the shortest doubling time when grown in Tris-acetate-phosphate (TAP) medium under a light intensity of 48-92 mu E/m(2)/s and a temperature of 36 C. Hydrogen production increased with increasing pH from 5.75 to 9.30; however, almost no production was observed at a pH of 5.25. Addition of 0.5 mM P-mercaptoethanol to the TAP medium stimulated hydrogen production about two-fold. During the hydrogen production phase, the use of TAP medium lacking both nitrogen and sulfur resulted in about 50% increase in the hydrogen production. This was in contrast to only a small increase in the production when either nitrogen or sulfur was omitted in TAP medium. The stimulation of hydrogen production by 0.5 mM beta-mercaptoethanol under nitrogen- and sulfur-deprived conditions occurred only when the cells were grown at a light intensity lower than 5 mu E/m(2)/s with no effects at higher intensities. Maximal calculated hydrogen production, 17.3-61.7 mu mol/mg Chl a/h, is a very high production rate compared to other green algae and makes Tetraspora sp. CU2551 an interesting model strain for photobiological hydrogen production.
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| 15. |
- Maneeruttanarungroj, Cherdsak, et al.
(författare)
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Sulfate permease (SulP) and hydrogenase (HydA) in the green alga Tetraspora sp CU2551 : Dependence of gene expression on sulfur status in the medium
- 2012
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487. ; 37:20, s. 15105-15116
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Tidskriftsartikel (refereegranskat)abstract
- The newly identified chloroplast envelope-localized sulfate permease gene (sulP) and the hydrogenase gene (hydA) from the green alga Tetraspora sp. CU2551 are reported in this study. The sulP showed an open reading frame of 1014 bp with the 5'- and 3'-UTR being 285 and 225 bp, respectively. The deduced amino acid sequence of SulP revealed an extended N-terminus where the putative chloroplast transit peptide was identified. This suggests a close relationship between Tetraspora and Chlamydomonas reinhardtii SulPs, as confirmed by phylogenetic tree analysis. In addition, the Tetraspora hydA was identified. The cDNA sequence showed an 878 bp encoding 292 amino acid residues. The deduced amino acid sequence of Tetraspora HydA is closely related to HydA of Chlorella fusca. The transcript levels of both sulP and hydA of Tetraspora showed an up-regulation of about 2.3 times after sulfur deprivation, whereas upon sulfur repletion the expression of both genes decreased. The production of H-2 and PSII activity decreased in cells grown under sulfur-deprived condition. These two activities could be restored when the cells were transferred to the medium supplemented with sulfur. Our results demonstrate a different response to sulfur deprivation between C. reinhardtii and Tetraspora sp. CU 2551.
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| 16. |
- Ramprakash, Balasubramani, et al.
(författare)
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Current strategies and future perspectives in biological hydrogen production : A review
- 2022
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Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 168
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Forskningsöversikt (refereegranskat)abstract
- Biohydrogen is a green and eco-friendly energy carrier with the potential to reduce our dependency on fossil fuels. Renewable biohydrogen production from waste biomass sources is potentially cheap; however, large-scale commercial production has not yet been achieved. Problems that need to be tackled include identifying industrially competent microorganisms, and appropriate bioreactor designs enabling novel hybrid methods such as integration of dark fermentation with electro-fermentation and utilization of microbial organisms doped with semiconducting nanomaterials for enhanced production. This review focuses on the production of hydrogen by biological methods, highlighting various fermentation processes, the role of enzymes, and different pretreatment methods. The waste materials used are briefly summarized, and current strategies in biological hydrogen production, including biomimetic and synthetic biology approaches, are assessed for their economic feasibility and their potential to contribute to net zero carbon emission. The lignocellulosic waste and the dynamic membrane bioreactor are the best suitable biomass and bioreactor, respectively for biohydrogen production. The integrated method of dark fermentation and electro-fermentation yields 41% higher hydrogen compared with dark fermentation alone. Finally, this review points out that significant efforts focusing on the development of hybrid fermentation technologies along with the development of novel engineered strains are needed for the commercial-scale production of biohydrogen in the future.
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| 17. |
- Tantong, Supaluk, et al.
(författare)
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Potential of Synechocystis PCC 6803 as a novel cyanobacterial chassis for heterologous expression of enzymes in the trans-resveratrol biosynthetic pathway
- 2016
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Ingår i: Protein Expression and Purification. - : Elsevier BV. - 1046-5928 .- 1096-0279. ; 121, s. 163-168
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Tidskriftsartikel (refereegranskat)abstract
- Selected model strains of phototrophic cyanobacteria have been genetically engineered for heterologous expression of numerous enzymes. In the present study, we initially explored the heterologous expression of enzymes involved in trans-resveratrol production, namely, the production of tyrosine ammonia-lyase, coumaroyl CoA-ligase, and stilbene synthase, in the unicellular cyanobacterium Synechocystis PCC 6803. Under the promoters Ptrc1Ocore and Ptrc1O, the respective genes were transcribed and translated into the corresponding soluble proteins at concentrations of 16-34 mu g L-1. The expression levels of these enzymes did not affect the growth rate of the cyanobacterial cells. Interestingly, coumaroyl CoA-ligase expression slightly increased the chlorophyll a content of the cells. Overall, our results suggest that the complete pathway of trans-resveratrol production can be engineered in Synechocystis PCC 6803.
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| 18. |
- Towijit, Umaporn, et al.
(författare)
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Co-overexpression of native phospholipid-biosynthetic genes plsX and plsC enhances lipid production in Synechocystis sp PCC 6803
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- The overexpression of native plsX and plsC genes involving in fatty acid/phospholipid synthesis first timely-reported the significantly enhanced lipid contents in Synechocystis sp. PCC 6803. Growth rate, intracellular pigment contents including chlorophyll a and carotenoids, and oxygen evolution rate of all overexpressing (OX) strains were normally similar as wild type. For fatty acid compositions, saturated fatty acid, in particular palmitic acid (16:0) was dominantly increased in OX strains whereas slight increases of unsaturated fatty acids were observed, specifically linoleic acid (18:2) and alpha-linolenic acid (18:3). The plsC/plsX-overexpressing (OX + XC) strain produced high lipid content of about 24.3% w/dcw under normal condition and was further enhanced up to 39.1% w/dcw by acetate induction. This OX + XC engineered strain was capable of decreasing phaA transcript level which related to poly-3-hydroxybutyrate (PHB) synthesis under acetate treatment. Moreover, the expression level of gene transcripts revealed that the plsX-and plsC/plsX-overexpression strains had also increased accA transcript amounts which involved in the irreversible carboxylation of acetyl-CoA to malonyl-CoA. Altogether, these overexpressing strains significantly augmented higher lipid contents when compared to wild type by partly overcoming the limitation of lipid production.
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| 19. |
- Wutthithien, Palaya, et al.
(författare)
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Improvement of photobiological hydrogen production by suspended and immobilized cells of the N-2-fixing cyanobacterium Fischerella muscicola TISTR 8215
- 2019
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Ingår i: Journal of Applied Phycology. - : SPRINGER. - 0921-8971 .- 1573-5176. ; 31:6, s. 3527-3536
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Tidskriftsartikel (refereegranskat)abstract
- To develop H-2 photoproduction by using the N-2-fixing cyanobacterium Fischerella muscicola TISTR 8215, a novel strain isolated from soil in Thailand, the factors affecting H-2 production were investigated in this study. Enhanced H-2 production in suspension culture was obtained when adapting the cells under N-2-fixing condition (modified AA medium) with continuous illumination of 250 mu mol photons m(-2) s(-1) under aerobic condition for 24 h, followed by further incubation under anaerobic condition for 9 h for production phase. The maximum H-2 production rate was 38.5 mu mol mg(-1) chl a h(-1). Low concentration of Fe2+ and Mo6+, essential elements for nitrogenase, enhanced H-2 production. The enhanced H-2 production was accompanied by the upregulation of nifD. On the other hand, an increased hupL transcript level was observed when there was a decrease of H-2 production. In cells immobilization, 1.5% (w/v) agar-immobilized cells had a 23-fold increase in maximum H-2 yield compared with that using free cell suspension at the same cell concentration, i.e., 7.48 mmol H-2 L-1 by immobilized cells and 0.32 mmol H-2 L-1 by suspended cells. Moreover, cell immobilization in agar could prolong H-2 production up to 108 h. This study underlines the strategies toward enhanced and sustained H-2 production from cyanobacteria. Furthermore, it will pave the way for large-scale production of biohydrogen to be used as an eco-friendly energy resource.
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