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1
Jensen, Brandi Jean. "The role of infrared radiation in the evolution and ecology of anaerobic photosynthetic bacteria". Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1594477811&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Waidner, Lisa A. "Abundance, diversity, and distribution of aerobic anoxygenic phototrophic bacteria in the Delaware estuary". Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file, 219 p, 2007. http://proquest.umi.com/pqdweb?did=1362525071&sid=2&Fmt=2&clientId=8331&RQT=309&VName=PQD.
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Falcone, Deane Louis. "Regulation of CO₂ fixation in photosynthetic bacteria /". The Ohio State University, 1992. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487779914825823.
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Bertling, Karl. "Use of lasers for the cultivation of photosynthetic bacteria /". [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19499.pdf.
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Bonnett, Tracey Clare. "Molecular biology of dimethyl sulphoxide respiration in photosynthetic bacteria". Thesis, University of East Anglia, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.282958.
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Call, Toby Primo. "Optimizing electrogenic activity from photosynthetic bacteria in bioelectrochemical systems". Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/280674.
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The aims of this project were to investigate a range of limitations affecting the electrical performance of bioelectrochemical systems (BES) and their use as analytical tools. The model cyanobacterium Synechocystis sp. PCC6803 was used to characterize light-driven BESs, or biophotovoltaic (BPV) devices. The phycobilisome (PBS) antenna size was altered to modify light absorption. At low to medium light intensities the optimum PBS antenna size was found to consist of one phycocyanin (PC) disc. Incorporating pulsed amplitude fluorescence (PAM) measurements into the BPV characterization allowed simultaneous comparison of photosynthetic efficiency to EET in Synechocystis. Non-photochemical quenching (NPQ) was investigated as a limiting factor in biophotovoltaic efficiency and was found to be reduced in the PBS antenna-truncated mutants. Fluorescence and electrochemical data were combined to develop a framework for quantifying the efficiency of light to bioelectricity conversion. This approach is a first step towards a more comprehensive and detailed set of analytical tools to monitor EET in direct relation to the underlying photosynthetic biology. A set of metabolic electron sinks were deleted to remove a selection of pathways that might compete with extracellular electron transfer (EET). The combined deletion of a bi-directional hydrogenase - HoxH, nitric oxide reductase - NorB, cytochrome-c oxidase - COX, bd-quinol oxidase - cyd, and the respiratory terminal oxidase - ARTO, roughly doubled light driven electron flux to EET. Deletion of nitrate reductase - NarB, and nitrite reductase - NirA, increased EET to a similar degree, but combination with the other knockouts compromised cell viability and did not increase output further. In addition to Synechocystis, the purple non-sulphur α-proteobacterium Rhodopseudomonas palustris CGA009 was used to test the effect of storage molecule synthesis knockout in a more industrially relevant organic carbon source driven BES, or microbial fuel cell (MFC). However, the removal of glycogen and poly-ß-hydroxybutyrate (PHB) did not have a significant effect on electrical output. Finally, the importance of electrode material and design for cell to anode connections in an MFC was investigated. EET from R. palustris was greatly enhanced using custom designed graphene and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) aerogels. Pristine graphene is also shown for the first time to be a viable, low cost alternative to platinum as a cathodic catalyst. Together, these results present a holistic view of major limitations on electrical output from BESs that may contribute to enhancing EET for power generation from MFCs in the long term, and optimization of BPV devices as reliable analytical tools in the short term.
7
Mulvaney, Rachel Margaret. "Studies of light harvesting complexes from purple photosynthetic bacteria". Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/4758/.
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In this thesis light harvesting complexes, the LH2 and core complexes, from several different species of purple photosynthetic bacteria have been analysed both functionally and structurally. Purified monomeric core complexes from Rhodopseudomonas (Rps.) palustris have been used to isolate and identify the putative Protein W. This information was then used to create a Protein W deletion mutant. A low-resolution crystal structure of the monomeric core complex from Allochromatium (Alc.) vinosum is presented which suggests that the LH1 complex is a complete ellipse, unlike the core complex from Rps. palustris. It has previously been shown that some species are able to synthesise LH2 complexes that have different NIR absorption spectra. For example, strains 7050 and 7750 of Rps. acidophila can express both the B800-850 and B800-820 LH2 complexes, whilst strain 10050 only expresses the B800-850 LH2 complex despite evidence to suggest that this strain contains multiple LH2 genes (pucBA genes). It is this homogeneity that has made the LH2 complexes from this strain structurally amenable. Here, genomic DNA from Rps. acidophila strain 10050 has been isolated and sequenced using the next generation sequencing (NGS) technique, Illumina sequencing. So far 8 pucBA gene pairs were identified arranged into 2 distinct operons, one containing B800-850 pucBA genes and pucC, the putative Bchl transporter that is essential for efficient LH2 expression. The second operon contains B800-820 pucBA gene pairs only. Analysis of the protein products of the B800-850 type pucBA gene pairs has shown that none of these proteins match the sequence for the LH2 that is expressed by Rps. acidophila strain 10050. The crystal structure of the LH2 complex from the culture of Rps. acidophila used to isolate the genomic DNA was resolved to 2.05 Å from crystals of the LH2 complex. This structure shows that the protein sequence of the LH2 complex has not changed. Hence, not all the pucBA gene pairs have been identified in the genome sequence data. Currently mate-pair sequencing is being completed to fill in the gaps of sequence data and to complete the genome sequence. LH2 complexes contain carotenoid (Car) and Bchl molecules. In this thesis, the energy transfer mechanisms between Car and Bchl molecules have been investigated using 2-dimensional electronic spectroscopy (2DES). This technique splits the emission and excitation events on 2-dimensions, which can make the less populated ‘dark’ states more visible as overlapping peaks can be separated. Car moleucles are not seen as theoretically efficient in photosynthesis. This is due to short life times of the excited state S2. However, the Car used in photosynthesis have conjugated carbon tails with ≥9 π electrons. According to calculations by Tavan and Schulten, these molecules have the propensity to contain additional excited states that lie below the S2 state that can be involved in energy transfer and increase the efficiency of energy transfer between the Car and Bchl molecules. For the first time an intermediate Car electronic state has been directly observed and shown to be involved in energy transfer between the Car and Bchl molecules.
8
Maeda, Hiroshi. "Vitamin E functions in photosynthetic organisms". Diss., Connect to online resource - MSU authorized users, 2006.
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Zilsel, Joanna. "Studies on inter-species expression of photosynthesis genes in Rhodobacter capsulatus". Thesis, University of British Columbia, 1990. http://hdl.handle.net/2429/29902.
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The primary amino acid sequences of the L, M, and H photosynthetic reaction center peptide subunits from a number of purple non-sulfur bacteria, including Rhodopseudomonas viridis, Rhodobacter sphaeroides, and Rhodobacter capsulatus have been previously shown to be highly homologous, and detailed X-ray crystallographic analyses of reaction centers from two species of purple non-sulfur bacteria, Rps. viridis and R. sphaeroides have shown that all recognized structural and functional features are conserved. Experiments were undertaken to determine whether genes encoding reaction center and light harvesting peptide subunits from one species could be functionally expressed in other species. Plasmid-borne copies of R sphaeroides and Rps. viridis pigment binding-peptide genes were independently introduced into a photosynthetically incompetent R. capsulatus mutant host strain, deficient in all known pigment-binding peptide genes. The R. sphaeroides puf operon, which encodes the L and M subunits of the reaction center as well as both peptide subunits of light harvesting complex I, was shown to be capable of complementing the mutant R. capsulatus host. Hybrid reaction centers, comprised of R. sphaeroides-encoded L and M subunits and an R. capsulatus-encoded H subunit, were formed in addition to the R. sphaeroides-encoded LHI complexes. These hybrid cells were capable of photosynthetic growth, but their slower growth rates under low light conditions and their higher fluorescence emission levels relative to cells containing native complexes, indicated an impairment in energy transduction. The Rps. viridis puf operon was found to be incapable of functional expression in the R. capsulatus mutant host. Introduction of a plasmid-borne copy of the Rps. viridis puhA gene, which encodes the H subunit of the reaction center, into host cells already containing the Rps. viridis puf operon, such that all structural peptides of the Rps. viridis reaction center were present, still did not permit stable assembly of Rps. viridis photosynthetic complexes. RNA blot analysis demonstrated that the barrier to functional expression was not at the level of transcription. Differences between Rps. viridis and R. sphaeroides that may account for their differing abilities to complement the R. capsulatus mutant host strain are discussed.Science, Faculty of
Microbiology and Immunology, Department of
Graduate
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Horken, Kempton M. "Isolation of photosynthetic membranes and submembranous particles from the cyanobacterium synechococcus PCC 7942". Virtual Press, 1996. http://liblink.bsu.edu/uhtbin/catkey/1036184.
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Photosynthetic membranes were prepared from the cyanobacterium Synechococcus PCC 7942 with oxygen evolving specific activity of 250-300 µmoles 02/ mg chl/hr. The membranes retained activity with a half-life of 4-5 days when stored at 0°C, or when quickly frozen in liquid nitrogen, greater than 95% of the activity remained after 2 months. Attempts to purify homogeneous preparations of photosystem II complexes from these membranes by detergent extraction were unsuccessful as indicated by a lack of a significant increase in oxygen evolution specific activity of the detergent extracts. Photosynthetic membrane detergent extracts usually maintained the same oxygen evolution specific activity as the orginal membranes, and a considerable amount of Photosystem I activity (75 µmoles 02 consumed /mg chl/hr in the Mehler reaction) was still present. The donor side of the photosystem II particles in the detergent extract was intact since the artificial electron acceptor, 2,6-dichiorophenolindophenol (DCPIP), was reduced at a rate comparable to the oxygen evolving activity. All oxygen evolving activity of the detergent extracts was lost when ion-exchange chromatography was used to resolve the co-extracted photosystem II and photosystem I complexes.Department of Biology
11
Hunter, David A. "Spin-correlated radical pairs in photosynthetic systems, micelles and liquids". Thesis, University of Oxford, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253134.
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Sari, Suleyman. "Development Of Helical Tubular Reactor For Hydrogen Producing Photosynthetic Bacteria". Master's thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608207/index.pdf.
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Photobiological hydrogen production from organic materials occurs with the help of illumination and under aerobic conditions within photobioreactors. Novel designs are needed in order to increase the light conversion efficiency and to improve the biological hydrogen production. In this thesis, purple non sulfur bacteria Rhodobacter sphaeroides O.U. 001 was employed as the hydrogen producing microorganism. Two different types of photobioreactors, namely oscillatory helical photobioreactor and recycling helical bioreactor, were devised and successfully operated for bacterial growth and hydrogen production.
Total liquid capacity of the pneumatically driven oscillatory flow helical tubular photobioreactor was 11.5 L, and 4.5 L of which was occupied by the bacterial culture. The bacteria grew very well both in malate-based and acetate-based media under nitrogen atmosphere. The bacteria sustained their vitality 24 days before the system was shut down.
The recycling helical tubular photobioreactor, which was developed for hydrogen production, had a fully occupied total volume of 6.5L. The bacteria produced approximately 1.9L of hydrogen in four days on malate-based media. The hydrogen production rate was 0.009LH2/Lculture.h.
The effects of molecular nitrogen gas and the sodium glutamate concentration on the growth of hydrogen producing photosynthetic bacteria Rhodobacter sphaeroides O.U.001 in the reactor were also examined in 500ml-bottles. The bacterial growth curves did not show any difference at the control medium containing 15mM of acetate and 10 mM of sodium glutamate. However, other bottles containing a lesser amount of N-source was found to grow earlier under the nitrogen atmosphere. Besides, even a 15/2 acetate/sodium glutamate ratio was observed to be sufficient to grow the bacteria for inoculation, and to spend extra sodium glutamate was not necessary.
The novel designs developed in this study aim to improve the biological hydrogen production by photosynthetic bacteria, and to provide new ways in adaptation of photobiological systems to outdoor conditions for large-scale applications.
13
Carpenter, Joanna Katharine Hicks. "Magnetic field effects on electron transfer reactions in photosynthetic bacteria". Thesis, University of Oxford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390466.
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Lightfoot, D. A. "Isolation and characterisation of nitrogen assimilation genes from photosynthetic bacteria". Thesis, University of Leeds, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.355472.
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Tzalis, Dimitrios. "A characterization of psbO mutant genes encoding the 33 kDa protein in a cyanobacterium". Virtual Press, 1992. http://liblink.bsu.edu/uhtbin/catkey/845939.
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This research was an attempt to characterize previously constructed mutants with a specifically altered psbO gene which encodes a 33 kDa protein active in photosynthesis. This polypeptide was believed to function in stabilization of manganese ions during photolysis of water at the photosystem II. The initial phase of this work was concerned with determining the manganese content of the genetically manipulated PS II particles of the photosynthetically active cyanobacteria.We found however, that the results of the isolation procedure for PS II particles of photosynthetically active cyanobacteria as described by Burnap et al. was not reproducible in our research organism. This prevented the chemical characterization of function of these particles as had been planned.In the second phase of the research sequencing of the mutated gene was to be performed for several clones in order to determine the kinds of specific alterations that had been made. The mutated genes had been cloned into both pUC1 20 and pPGV5 vectors which were transformed into Escherichia OR (EQQJi) and the cyanobacterium Synechococcus PCC 7942, respectively.Several attempts were mad o isolate plasmid DNA from both the transformed E QQJI and cyanobacterium. Isolation of pUC120 DNA was not achieved due to the toxicity of the 33 kDa protein product of the psbO gene in sgJj. The pPGV5 plasmid isolation was successful and PCR-sequencing was performed. However, the sequencing did not result in a readable sequence. Instead, banding patterns showed more than one nucleotide per lane. Since pPGV5 contains a strong constitutive promoter, a large amount of mutant protein was being produced. Our findings suggested that transformed cyanobacteria may have been under pressure to revert the altered gene to wild-type. Thus, upon growth of a single colony to a larger volume, a heterogeneous population of cells with different sizes of plasmids may have resulted. Restriction analysis of isolated plasmid DNA confirmed the presence of multiple-sized plasmid molecules. Therefore, this research has shown that the previously constructed mutants are not stable enough to characterize for alterations in manganese binding.Department of Biology
16
Lee, Sengyong. "Analyses of mutants in the 33 kDa manganese stabilizing protein of photosystem II and construction of a deletion mutant in synechococcus PCC 7942". Virtual Press, 1993. http://liblink.bsu.edu/uhtbin/catkey/865930.
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The 33 kDa manganese stabilizing protein (MSP) has been proposed to provide ligands to stabilize Mn ions in the water lysis reaction of photosystem II of photosynthesis. In previous research site-directed mutagenesis had been performed on regions of the psbO gene encoding two aspartic acid residues of MSP which were thought to have the potential to form carboxyl bridges with Mn ions. The purpose of this research was to analyze these mutants. Plasmids pUC120-33 (#1,3,5,7,9,11,15) containing mutant psbO genes could not be isolated from E.coli because the expressed MSP was toxic to the cells. However, a psbO mutant gene carried in pPGV5-33 (#7) was isolated from E.coli and transformed into cyanobacterium Svnechococcus PCC 7942. Cyanobacterial cells carrying the MSP mutant showed a susceptibility to intensive light (100 footcandles) with a decrease of 30% in the growth rate within the first 100 hours after inoculation. This result suggested a possible function of the MSP in protecting the oxygen evolving complex from intensive light exposure. However, the mutant appeared to revert after this time probably due to homologous gene recombination with the wild type gene. In order to further analyze the function of mutants without recombination occurring, the construction of an MSP deletion was attempted using insertion of a kanamycin cartridge into the middle of the psbO gene. The inactivated psbO gene was transformed into E.coli and transformants were selected by kanamycin resistance. However, plasmid DNA carrying the interrupted genes could not be isolated, probably due to toxicity of the expression product in E.coli cells. Thus, future studies should be directed to reconstruction of a deletion mutant by direct transformation into cyanobacterial cells. Once a deletion mutant has been constructed analyses of the site-directed mutations could be performed in cyanobacteria.Department of Biology
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Zhang, Shiming. "A mutagenesis study on photoreaction centers of two purple photosynthetic bacteria". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2000. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape2/PQDD_0012/NQ52200.pdf.
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McLuskey, Karen. "Crystallographic studies on integral membrane light harvesting complexes from photosynthetic bacteria". Thesis, University of Glasgow, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.266747.
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Fredericks, Mark Christopher. "Characterisation of the light independent reduction of protochlorophyllide in photosynthetic bacteria". Thesis, University of Bristol, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.390132.
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Grégoire, Daniel. "Photosynthetic and Fermentative Bacteria Reveal New Pathways for Biological Mercury Reduction". Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/38722.
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Mercury (Hg) is a global pollutant and potent neurotoxin that bioaccumulates in aquatic and terrestrial food webs as monomethylmercury (MeHg). Anaerobic microbes are largely responsible for MeHg production, which depends on the bioavailability of inorganic Hg substrates to methylators. Hg redox cycling pathways such as Hg reduction play a key role in determining Hg’s availability in the environment. Although abiotic photochemical Hg reduction typically dominates in oxic surface environments, Hg reduction pathways mediated by photosynthetic and anaerobic microbes are thought to play an important role in anoxic habitats where light is limited and MeHg production occurs. Currently, the physiological mechanisms driving phototrophic and anaerobic Hg reduction remain poorly understood. The main objective of my thesis is to provide mechanistic details on novel anaerobic and phototrophic Hg reduction pathways. I used a combination of physiological, biochemical and trace Hg analytical techniques to study Hg reduction pathways in a variety of anaerobic and photosynthetic bacteria. I demonstrated that Hg redox cycling was directly coupled to anoxygenic photosynthesis in aquatic purple non-sulphur bacteria that reduced HgII when cells incurred a redox imbalance. I discovered that terrestrial fermentative bacteria reduced Hg through pathways that relied on the generation of reduced redox cofactors. I also showed that sulphur assimilation controlled Hg reduction in an anoxygenic phototroph isolated from a rice paddy. In addition, I developed methods to explore cryptic anaerobic Hg redox cycling pathways using Hg stable isotope fractionation. At its core, my thesis underscores the intimate relationship between cell redox state and microbial Hg reduction and suggests a wide diversity of microbes can participate in anaerobic Hg redox cycling.
21
Bentley, Fiona K., i n/a. "Investigation into the roles of the PsbL, PsbM, PsbT and Psb27 subunits of Photosystem II in Synechocystis sp. PCC 6803". University of Otago. Department of Biochemistry, 2008. http://adt.otago.ac.nz./public/adt-NZDU20080627.151048.
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The PsbL, PsbM and PsbT subunits of photosystem II (PSII) are single-helix membrane-spanning proteins found at the monomer-monomer interface that may stabilize the dimeric complex. This study has characterised strains of Synechocystis sp. PCC 6803 where psbL, psbM and psbT have been interrupted by the insertion of antibiotic-resistance cassettes. The [Delta]PsbL strain exhibited slowed growth that correlated with a disruption in PSII assembly leading to an accumulation of CP43-less PSII monomers. Moreover, the [Delta]PsbL:[Delta]PsbM and [Delta]PsbL:[Delta]PsbT double mutants were not photoautotrophic. In contrast, the [Delta]PsbM and [Delta]PsbT strains grew photoautotrophically and supported oxygen evolution, albeit at reduced rates compared to wild type. S-state analyses showed that the removal of PsbM or PsbT did not affect the donor side reactions of PSII, which includes the oxidation of water, however, the removal of PsbT impaired electron flow between Q[A] and Q[B] on the acceptor side of PSII. Blue-Native PAGE revealed that removal of either PsbM or PsbT was insufficient to entirely disrupt dimer formation; however, the combined removal of PsbM and PsbT resulted in the predominance of monomeric forms of PSII in the [Delta]PsbM:[Delta]PsbT strain. Under high light (2 mE m⁻� s⁻� at 30�C), [Delta]PsbM and [Delta]PsbT cells were considerably more susceptible to photoinactivation than wild type; however, they were able to fully recover in a protein synthesis-dependent manner when returned to moderate light levels (0.03 mE m⁻� s⁻�). A requirement for Psb27 was found in the protein-synthesis-dependent recovery of photoinactivated [Delta]PsbT cells. More significantly, an absolute functional requirement was found for Psb27 in the [Delta]PsbM strain, where functional PSII complexes are not assembled in the absence of Psb27. These results suggest that Psb27 is critical for PSII assembly in the absence of PsbM, and also for the protein-synthesis-dependent recovery of PSII in the absence of PsbT. Moreover, in addition to Psb27, the PsbU subunit of the oxygen-evolving complex was also found to be an absolute functional requirement in the [Delta]PsbM strain, where functional PSII centres are not assembled when both PsbM and PsbU are absent. It appears, therefore, that PsbM has crucial functional interactions with specific extrinsic proteins located in the vicinity of the oxygen-evolving complex. Interestingly, the [Delta]PsbM strain was also found to have a high susceptibility to suppressor mutations, indicating it has important functional roles in the cyanobacterial cell.
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Sani, A. "Ribulose-1,5-biphosphate carboxylase-oxygenase and carbon dioxide fixation in the Rhodospirillaceae". Thesis, University of Warwick, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372232.
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Fursman, Catherine E. "Electron spin echo envelope modulation spectroscopy of radical pairs in photosynthetic bacteria". Thesis, University of Oxford, 2000. http://ora.ox.ac.uk/objects/uuid:1ccaf0e5-3a45-4f13-a184-a4f1cf772c9b.
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Electron spin echo envelope modulation (ESEEM) spectroscopy is widely used to study the radical pairs created during the primary steps of photosynthesis. In this thesis the analysis of ESEEM spectra is improved, and some new applications and variations of this experiment suggested. Experimental spectra from species such as P+Q-A, the secondary radical pair formed in the reaction centre of the bacterium Rhodobacter sphaeroides, give information about the exchange and dipolar couplings between the radicals. The model used to analyse the data affects the results; this thesis suggests two improvements. First, the effect of anisotropic hyperfine couplings in the radicals is considered by the addition of a single spin-1/2 nucleus to the model. This approach suggests that previous models neglecting the effect of nuclei may have been slightly in error. Secondly, several model fittings are performed in the time domain. This approach avoids the Fourier transformation to the frequency domain so that experimental dead-time does not corrupt the data. An excellent fit to experimental data is found with a model containing one spin-1/2 nucleus on each radical. The hyperfine coupling parameters resulting from the fit are consistent with independent experimental results. Use is made of the method of Cramér-Rao lower bounds to assess the precision to which experimental parameters are determined from a time domain curve fitting. It is shown that the lower bounds may also be used to determine the optimum sampling strategy for the experiment. An example is given of the novel use of ESEEM to determine the distance between the radicals in the strongly coupled, uncorrelated radical pair Q-AQ-B ESEEM has not yet been used for this purpose, and the simulated spectra produced here indicate that the experiment could be used to evaluate the dipolar coupling and hence the inter-radical distance. This thesis considers the possibility of performing ESEEM at higher frequencies than are usually considered. Calculations show that the increased resolution of the g-tensors allow an experiment performed at the W-band frequency of 95 GHz to make a correlation between the relative orientations of the radicals and the dipolar axis, information which has previously been unavailable from a single experiment.
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Teiseh, Eliasu Azinyui. "Anaerobic hydrogen production by photosynthetic purplenonsulfur [sic] bacteria using volatile fatty acids". Laramie, Wyo. : University of Wyoming, 2008. http://proquest.umi.com/pqdweb?did=1594490411&sid=1&Fmt=2&clientId=18949&RQT=309&VName=PQD.
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Fraser, Niall Johnston. "Modified pigments and mechanisms of energy transfer in LH2 complexes from purple bacteria". Thesis, University of Glasgow, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.301678.
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Sarcina, Maria. "Pigment-protein interactions within photosystem II". Thesis, Imperial College London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.313030.
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Bombelli, Paolo. "Harnessing solar energy by bio-photovoltaic devices". Thesis, University of Cambridge, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.610451.
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Kamal, Varsha Subhash Carleton University Dissertation Biology. "The anaerobic, phototrophic metabolism of 3-chlorobenzoate by Rhodopseudomonas Palustris". Ottawa, 1992.
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Muhiuddin, Irine Parveen. "Paramagnetic resonance studies of redox components in type-I (ferredoxin-reducing) bacterial photosynthetic reaction centres". Thesis, Queen Mary, University of London, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314170.
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de, Castro Francisco, Ursula Gaedke i Jens Boenigk. "Reverse evolution : driving forces behind the loss of acquired photosynthetic traits". Universität Potsdam, 2009. http://opus.kobv.de/ubp/volltexte/2010/4496/.
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Background:
The loss of photosynthesis has occurred often in eukaryotic evolution, even more than its acquisition, which occurred at least nine times independently and which generated the evolution of the supergroups Archaeplastida, Rhizaria, Chromalveolata and Excavata. This secondary loss of autotrophic capability is essential to explain the evolution of eukaryotes and the high diversity of protists, which has been severely underestimated until recently. However, the ecological and evolutionary scenarios behind this evolutionary ‘‘step back’’ are still largely unknown.
Methodology/Principal Findings:
Using a dynamic model of heterotrophic and mixotrophic flagellates and two types of prey, large bacteria and ultramicrobacteria, we examine the influence of DOC concentration, mixotroph’s photosynthetic growth rate, and external limitations of photosynthesis on the coexistence of both types of flagellates.
Our key premises are: large bacteria grow faster than small ones at high DOC concentrations, and vice versa; and heterotrophic flagellates are more efficient than the mixotrophs grazing small bacteria (both empirically supported). We show that differential efficiency in bacteria grazing, which strongly depends on cell size, is a key factor to explain the loss of photosynthesis in mixotrophs (which combine photosynthesis and bacterivory) leading to purely heterotrophic lineages. Further, we show in what
conditions an heterotroph mutant can coexist, or even out-compete, its mixotrophic ancestor, suggesting that bacterivory and cell size reduction may have been major triggers for the diversification of eukaryotes.
Conclusions/Significance:
Our results suggest that, provided the mixotroph’s photosynthetic advantage is not too large, the (small) heterotroph will also dominate in nutrient-poor environments and will readily invade a community of mixotrophs and bacteria, due to its higher efficiency exploiting the ultramicrobacteria. As carbon-limited conditions were presumably widespread throughout Earth history, such a scenario may explain the numerous transitions from phototrophy to mixotrophy and further to heterotrophy within virtually all major algal lineages. We challenge prevailing concepts that affiliated the evolution of phagotrophy with eutrophic or strongly light-limited environments only.
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Borrego, i. Moré Carles. "Heterogeneïtat pigmentària en bacteris fotosintètics verds: fisiologia i significació ecològica". Doctoral thesis, Universitat de Girona, 1996. http://hdl.handle.net/10803/96755.
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Green bacteria possess one of the most complexes antenna systems within the group of the photosynthetic microorganisms. One reason for this complexity is the high diversity of pigments antenna, the bacteriochlorophylls (BChls c, d or e), consisting of a mixture of various forms regularly arranged within the antenna units (the chlorosomes). This pigment diversity makes difficult the accurate analysis and identification of the different bacteriochlorophylls forms by the conventional spectrophotometrical techniquesEls bacteris verds posseeixen un dels sistemes antena més complexes dins el grup dels microorganismes fotosintètics. Una de les raons d’aquesta complexitat és l’elevada diversitat de pigments antena, especialment pel que fa a les bacterioclorofil•les (BCIs c, d o e). Cadascuna d’aquestes BCIs, que tenen diferents estructures i propietats òptiques, es composa d’una mescla de diverses formes homòlogues disposades ordenadament a l’interior de les unitats antena (clorosomes). Aquesta diversitat pigmentària dificulta enormement l’anàlisi i identificació d’aquests pigments mitjançant les tècniques espectrofotomètriques tradicionals
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Perry, Leslie M. "Regulation of Alternative Sigma Factors During Oxidative and Ph Stresses in the Phototroph Rhodopseudomonas Palustris". Thesis, University of North Texas, 2014. https://digital.library.unt.edu/ark:/67531/metadc700009/.
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Rhodopseudomonas palustris is a metabolically versatile phototrophic α-proteobacterium. The organism experiences a wide range of stresses in its environment and during metabolism. The oxidative an pH stresses of four ECF (extracytoplasmic function) σ-factors are investigated. Three of these, σ0550, σ1813, and σ1819 show responses to light-generated singlet oxygen and respiration-generated superoxide reactive oxygen species (ROS). The EcfG homolog, σ4225, shows a high response to superoxide and acid stress. Two proteins, one containing the EcfG regulatory sequence, and an alternative exported catalase, KatE, are presented to be regulated by σ4225. Transcripts of both genes show similar responses to oxidative stress compared to σ4225, indicating it is the EcfG-like σ-factor homolog and controls the global stress response in R. palustris.
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Law, Christopher J. "Structure and function studies on the LH1-RC core complex from a range of photosynthetic purple bacteria". Thesis, University of Glasgow, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.284738.
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Do, Thi Lien, Thi To Uyen Do, Thi Nhi Cong Le, Phuong Ha Hoang i Thi Ngoc Mai Cung. "Optimization production conditions of photosynthetic purple bacteria biomass at pilot scale to remove sulphide from aquaculture pond". Technische Universität Dresden, 2018. https://tud.qucosa.de/id/qucosa%3A32725.
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For the purpose of sulphide removal in aquaculture ponds, three strains (name: TH21, QN71, QN51) were isolated and selected with the highest sulphide removal activity from Thanh Hoa and Quang Ninh coastal zones. These strains have identified and tested in a number of aquaculture ponds in different areas with good water quality results. With the objective of purple non sulfur bacteria biomass production containing 3 selected strains for wide application and suitable price for farmers, in this study, we study on optimum conditions of mixed purple non sulfur bacteria biomass production at pilot scale. The results showed that the sources of substrates were soybean meal (1g/l) and acetate (0.5g/l). These substrates are low cost, easy to find, convenient in large culture. The mixture of photosynthetic bacteria can be cultured in glass tanks, under micro aerobic and natural lighting conditions that produce highly concentrated photosynthetic bacteria and lowest rest media.Nhằm mục tiêu xử lý sulphide trong môi trường nuôi trồng thủy sản, chúng tôi đã phân lập và lựa chọn được ba chủng vi khuẩn tía quang hợp có khả năng loại bỏ sulphide cao nhất ký hiệu TH21, QN71, QN52 từ các vùng ven biển Thanh Hóa và Quảng Ninh. Các chủng này đã được định loại và thử nghiệm tại một số ao nuôi thủy sản ở các vùng khác nhau thu được kết quả tốt về chất lượng nước. Để tạo chế phẩm vi khuẩn tía quang hợp từ 3 chủng lựa chọn được ứng dụng rộng rãi và có giá thành phù hợp cho nông hộ, trong nghiên cứu này, chúng tôi nghiên cứu tối ưu hóa các điều kiện sản xuất sinh khối hỗn hợp 3 chủng vi khuẩn tía quang hợp ở quy mô pilot. Kết quả cho thấy đã tìm kiếm được nguồn cơ chất là bột đậu tương (1g/l) và acetate (0.5g/l) là những chất có giá thành thấp, dễ tìm kiếm, thuận tiện trong nhân nuôi ở quy mô lớn. Hỗn hợp vi khuẩn tía quang hợp có thể nuôi trong các bể kính, ở điều kiện vi hiếu khí, có ánh sáng chiếu tự nhiên có thể sản xuất được chế phẩm vi khuẩn tía quang hợp có mật độ cao, cơ chất còn lại sau sản xuất là ít nhất.
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Pinoargote, Gustavo, i Gustavo Pinoargote. "Evaluation of Probiotics Solutions in Shrimp Aquaculture and Their Effectiveness Against Acute Hepatopancreatic Necrosis Disease Caused By Vibrio parahaemolyticus Strain A3". Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/626325.
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As the demand for farmed shrimp continues to grow worldwide, the use of probiotics to address the sustainability of aquaculture fisheries has gained much attention. Emerging diseases in shrimp aquaculture, such as acute hepatopancreatic necrosis disease (AHPND), have devastating economic impacts in countries that largely depend on this activity. The relevance of this research lies on the fact that it explores the potential of using probiotics to mitigate the negative effects of AHPND in shrimp aquaculture. The scope of these studies includes survival of probiotic microbes in typical aquaculture water conditions, the effectiveness of probiotics in vitro and in vivo against the pathogenic strain of Vibrio parahaemolyticus that causes AHPND, and the effects of probiotics on the bacterial community composition in aquaculture water and gastrointestinal tract of shrimp after an induced AHPND infection.
The microorganisms chosen as probiotics for this research include a lactic acid bacterium, a yeast and a photosynthetic bacterium. Informal feedback from shrimp farmers in Thailand and Vietnam revealed positive results against AHPND when using a commercially available probiotic containing multiple species of microorganisms from these probiotic groups.
This research was divided into four studies. The first study (Chapter 2) evaluated the growth of the three different probiotic microbes in two different salinity conditions commonly found in intensive shrimp production systems to determine whether they could be further considered as potential candidates. The hypothesis was that the NaCl concentrations of the media may not have an effect on acid production, growth and cell morphology of the microorganisms being evaluated due to their metabolic mechanisms of adaptation to differences in osmotic pressure. The probiotic microbes were cultured in nutrient media enriched with 1 and 2% NaCl. Microbial survival, acidity and cell morphology between treatments were compared using enumeration by serial dilutions and plating, pH measurements and scanning electron microscopy imaging, respectively. The results showed that salinity levels up to 2% NaCl did not affect the growth of lactic acid bacteria and yeast. Photosynthetic bacteria grown in media with 1% NaCl showed a 24-hour delay in comparison to the control and a prolonged lag phase that lasted 48 hours when the media contained 2% NaCl. Therefore, the hypothesis was partially supported. Based on these results, all three probiotic microbes demonstrated to be suitable for application in aquaculture ponds with up to 2% salinity.
The second study (chapter 3) aimed at determining the inhibitory effects of eight different formulations of probiotic solutions against the pathogenic strain of V. parahaemolyticus in vitro. The hypothesis of this study was that probiotic solutions containing whole microbial cultures of multiple microbial types including lactic acid bacteria may have a greater inactivation of the pathogen. The probiotic formulations consisted of individual cultures, combinations of the three probiotic microbes, and a commercially available probiotic formulation. The inhibitory effects were evaluated following a disk diffusion test on solid media by comparing diameters of zones of inhibition, and a challenge test in liquid media by comparing pathogen survival after exposure to probiotic solutions. Findings revealed inhibition zones with greater diameters in disks treated with whole microbial cultures (min: 7.83 mm, max: 11.33 mm) versus disks treated with only supernatants (min: 7.00 mm, max: 8.50 mm). Results from the challenge in liquid media tests showed greater inactivation of the pathogen after 48 h (6.56±0.07 to 5.43±0.03 log10 reduction) when treated with lactic acid bacteria alone and in combination with other microbial types. From these results, the hypothesis was supported and it was concluded that probiotic solutions including a lactic acid bacterium, the combination of lactic acid bacterium and photosynthetic bacterium and the combination of lactic acid bacterium, yeast and photosynthetic bacterium may be used to effectively inhibit AHPND in shrimp aquaculture.
The third study (chapter 4) explored the effects of probiotic solutions on live shrimp (Litopenaeus vannamei) pretreated with probiotics for 7 days prior to challenging them with the pathogenic V. parahaemolyticus strain causing AHPND. The hypothesis of this study was that higher shrimp survival and weight gains would be observed when shrimps are exposed to probiotics solutions with multiple microbial types in the water and feed. Water quality parameters (dissolved oxygen, temperature, acidity, salinity and total ammonia nitrogen), difference in shrimp weight increase and shrimp survival were compared between probiotic treatments and controls. Treatments included: (1) a lactic acid bacterium alone (Pro.Sol1), (2) a lactic acid bacterium and a photosynthetic bacterium (Pro.Sol2), (3) the combination of a lactic acid bacterium, a yeast, and a photosynthetic bacterium (Pro.Sol3), and (4) a commercial probiotic (Com.Pro) and the results showed shrimp survival of 11.7, 26.7, 36.7 and 73.3%, respectively. Also, treatments Pro.Sol3 and Com.Pro resulted in higher weight gains (19.7 and 31.2%, respectively) versus the negative control (11.2%). Moreover, onset of the disease was delayed in all treatments as follows: 12 h with Pro.Sol1, 20 h with Pro.Sol2, 22 h with Pro.Sol3, and 26 h with Com.Pro. From these results, the hypothesis was supported and it was concluded that probiotics have the potential to effectively mitigate the effects of AHPND in the shrimp aquaculture.
Finally, the fourth study (chapter 5) evaluated the effects of probiotics on the bacterial diversity of the gastrointestinal tract of shrimp as well as variation of bacterial and fungal diversity in the water before and after challenging shrimp with the pathogenic V. parahaemolyticus strain causing AHPND. The hypothesis of this study was that probiotic solutions with multiple microbial types may be able to maintain the microbial composition of the shrimp GI tract and aquaculture water preventing an increase in relative abundance of the family Vibrionaceae. Next generation sequencing was conducted using an Illumina MiSeq™ and primers specific for bacterial V4 hypervariable region of the 16S rRNA gene. The results obtained from the GI tract of shrimp revealed that the relative abundance of the family Vibrionaceae significantly increased in treatments with high mortalities, whereas treatments with higher survivals showed no significant difference in relative abundance of Vibrionaceae family members (P>0.05) in comparison to the negative control. The Shannon diversity index values (abundance and evenness) of the bacterial communities revealed that the treatment with the highest survival had the highest Shannon index value (4.69±0.133) whereas the treatment with lowest survival had the lowest Shannon index value (0.17±0.004). The results obtained from water samples did not show a higher abundance of the family Vibrionaceae, and diversity was maintained after infection (Shannon index 4.64±0.58). Regarding fungal diversity in water samples, Shannon index values revealed no significant changes before (3.627±0.37) and after infection (3.664±0.18) except for Pro.Sol3 (2.859±0.56) and Com.Pro (1.795±0.50), which included yeast in their formulation. Thus, the hypothesis of this study was partially supported since the results revealed that while all probiotics maintained the diversity of microbial composition in the water, only those probiotic solutions with various microbial types in the formulation maintained the diversity of the microbial composition in the GI tract of shrimp providing protection against AHPND.
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Aizouq, Mohammed [Verfasser]. "Characterization of Enzymes Involved in Lipid Biosynthesis from the Photosynthetic Bacteria Synechocystis PCC6803 and Blastochloris viridis / Mohammed Aizouq". Bonn : Universitäts- und Landesbibliothek Bonn, 2020. http://d-nb.info/1233733877/34.
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Sànchez, Martínez Olga. "Light-limited growth of Chromatium vinosum". Doctoral thesis, Universitat Autònoma de Barcelona, 1996. http://hdl.handle.net/10803/3911.
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Janousek, Christopher Nathan. "Functional diversity and composition of microalgae and photosynthetic bacteria in marine wetlands : spatial variation, succession, and influence on productivity /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2005. http://wwwlib.umi.com/cr/ucsd/fullcit?p3191994.
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Meyer, Terry, John Kyndt i Michael Cusanovich. "Occurrence and sequence of Sphaeroides Heme Protein and Diheme Cytochrome C in purple photosynthetic bacteria in the family Rhodobacteraceae". BioMed Central, 2010. http://hdl.handle.net/10150/610087.
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BACKGROUND:Sphaeroides Heme Protein (SHP) was discovered in the purple photosynthetic bacterium, Rhodobacter sphaeroides, and is the only known c-type heme protein that binds oxygen. Although initially not believed to be widespread among the photosynthetic bacteria, the gene has now been found in more than 40 species of proteobacteria and generally appears to be regulated. Rb. sphaeroides is exceptional in not having regulatory genes associated with the operon. We have thus analyzed additional purple bacteria for the SHP gene and examined the genetic context to obtain new insights into the operon, its distribution, and possible function.RESULTS:We found SHP in 9 out of 10 strains of Rb. sphaeroides and in 5 out of 10 purple photosynthetic bacterial species in the family Rhodobacteraceae. We found a remarkable similarity within the family including the lack of regulatory genes. Within the proteobacteria as a whole, SHP is part of a 3-6 gene operon that includes a membrane-spanning diheme cytochrome b and one or two diheme cytochromes c. Other genes in the operon include one of three distinct sensor kinase - response regulators, depending on species, that are likely to regulate SHP.CONCLUSIONS:SHP is not as rare as generally believed and has a role to play in the photosynthetic bacteria. Furthermore, the two companion cytochromes along with SHP are likely to function as an electron transfer pathway that results in the reduction of SHP by quinol and formation of the oxygen complex, which may function as an oxygenase. The three distinct sensors suggest at least as many separate functional roles for SHP. Two of the sensors are not well characterized, but the third is homologous to the QseC quorum sensor, which is present in a number of pathogens and typically appears to regulate genes involved in virulence.
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Toledo, Gerardo V. "Genetic diversity of the unicellular cyanobacteria Synechococcus in the California Current /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2000. http://wwwlib.umi.com/cr/ucsd/fullcit?p3025941.
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Tetreault, Michelle Lynn. "Investigation of the docking and electron transfer reactions between cytochrome c₂ and the reaction center from the photosynthetic bacteria Rhodobacter sphaeroides using site-directed mutants /". Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 1999. http://wwwlib.umi.com/cr/ucsd/fullcit?p9945781.
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Tzankov, Pancho. "Mechanisms of charge separation and protein relaxation processes in native and modified reaction centers of photosynthetic bacteria Rb. sphaeroides R26 studied by picosecond time resolved fluorescence". [S.l. : s.n.], 2003. http://deposit.ddb.de/cgi-bin/dokserv?idn=969393067.
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Forrest, Mary Elspet. "Studies on the transcription of photosynthesis genes of the photosynthetic bacterium Rhodobacter capsulatus". Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28778.
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Rhodobacter capsulatus is a Gram negative bacterium that exhibits a variety of growth modes, including chemoheterotrophic growth and photoheterotrophic growth. Upon a shift of cultures from high to low oxygen concentrations the photosynthetic apparatus is synthesized and incorporated into the inner membrane. The puf operon contains genes that encode structural proteins found in the light-harvesting and reaction center complexes. In a preliminary attempt to pinpoint the location of the puf promoter R. capsulatus RNA polymerase was purified by standard techniques and used in in vitro runoff
transcription assays. It was found that the polymerase was capable of specific transcription with linearized pUC13 DNA but no specific transcription could be obtained with K capsulatus DNA. It was concluded that some factor or condition necessary for specific transcription with R capsulatus DNA was absent from these assays. The location of the puf promoter was subsequently found through a series of deletions and oligonucleotide-directed mutations in the 5' region of the puf operon. Fragments that contained these mutations were placed translationally in-frame with the lacZ gene of Escherichia coli in plasmids that could be conjugated into K capsulatus. Assays of beta-galactosidase activities under low and high oxygen conditions resulted in localization of the promoter to a position approximately 540 basepairs upstream of what was previously believed to be the first gene of the operon, the pufB gene. RNA 5' end-mapping experiments showed that the quantity of RNA transcripts obtained were comparable to the lacZ activities. The existence of multiple low abundance RNA 5' ends prompted the theory that the primary transcript has a short half-life, and is rapidly processed to yield a more stable transcript with a 5' end that maps just upstream of the pufB gene. It was found that only the 5' end nearest to the promoter could be capped by guanylyl transferase, and this could only be detected when the putative processing sites were deleted. The DNA sequence between the promoter and the pufB gene contains a new gene of the puf operon, the pufO gene. Deletion of this gene showed that it plays an essential role in the formation of mature light-harvesting and reaction center complexes.Science, Faculty of
Microbiology and Immunology, Department of
Graduate
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Tambosi, Reem. "Stress and toxicity of metal in photosynthetic bacteria : multi-scale study of the effects and the targets of metal ions and nanoparticles Silver and Copper Acute Effects on Membrane Proteins and Impact on Photosynthetic and Respiratory Complexes in Bacteria Silver Effect on Bacterial Cell Membrane Structure Investigated by Atomic Force and Scanning Electron Microscopes Cadmium and Copper Cross-tolerance. Cu+ alleviates Cd2+ toxicity, and both cations target heme and chlorophyll biosynthesis pathway in Rubrivivax gelatinosus Additive effects of metal excess and superoxide, a highly toxic mixture in bacteria". Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASL070.
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L’usage intensif des métaux et des ions métalliques dans l'industrie et l'agriculture représente une menace sérieuse pour l'environnement et pour tous les êtres vivants en raison de la toxicité aiguë de ces ions. Cependant, cela peut aussi être un outil prometteur. En effet, les ions comme les nanoparticules d'argent sont très utilisés dans diverses applications médicales, industrielles et sanitaires. L'effet antimicrobien de ces nanoparticules est en partie lié aux ions Ag⁺ libérés et à leur capacité à interagir avec les membranes bactériennes. L'objectif de ce projet est d'étudier l'interaction entre un objet biologique (les bactéries) et des objets physiques (métaux), pour comprendre l'impact des métaux sous différentes formes (ions, nanoparticules et nanostructures) sur les cellules bactériennes en utilisant différentes approches: de physiologie, biochimie, génétique et de biologie cellulaire. Nous avons utilisé comme modèles biologiques, principalement la bactérie photosynthétique pourpre Rubrivivax (R.) gelatinosus, mais aussi Escherichia coli; et pour les objets physiques, nous avons utilisé l'argent comme métal principal mais aussi d'autres métaux (cuivre, cadmium et nickel) à titre de comparaison. Les principaux objectifs de ce travail sont: 1- d'étudier l'impact et les mécanismes de toxicité de ces ions métalliques / NPs sur les métabolismes bactériens respiratoire et photosynthétique. 2- Identifier des gènes bactériens impliqués dans la réponse à un excès d'ions Ag⁺. 3- Etudier l'internalisation et l'interaction des ions métalliques et des NP au sein des membranes biologiques. Ainsi, nous avons pu identifier, à la fois in vitro et in vivo, des cibles spécifiques d'ions Ag⁺ et Cu²⁺ dans la membrane des bactéries. Cela inclut des complexes impliqués dans la photosynthèse, mais également des complexes de la chaine respiratoire. Il a été démontré que les ions Ag⁺ et Cu²⁺ ciblent spécifiquement une bactériochlorophylle exposée au solvant dans les antennes de collecte de lumière du photosystème de la bactérie. Ceci présente également, à notre connaissance, la première preuve directe de dommages induits par des ions Ag⁺ sur les protéines membranaires impliquées dans ces métabolismes. Par ailleurs, nous avons également réalisé une étude comparative par microscopie (AFM/ MEB) de l'effet de l'Ag⁺ en solution ou des Ag-NPs synthétisés dans notre laboratoire, sur la morphologie des cellules bactériennesThe extensive use of metal ions in industry and agriculture represents a serious threat to the environment and to all living being because of the acute toxicity of these ions. However, it can also be a promising tool, silver ions and nanoparticles are some of the most widely used metals in various industrial and health applications. The antimicrobial effect of these nanoparticles is in part related to the released Ag⁺ ions and their ability to interact with bacterial membranes. The goal of this project is to study the interaction between biological subject (the bacteria) and physical objects (metals), and more specifically to understand the impact of metals in different forms (ions, nanoparticles and nanostructures) on the growth of the bacterial cells using different approaches : physiology, biochemistry, genetics and cell biology. We used as biological models, principally the purple photosynthetic bacterium Rubrivivax (R.) gelatinosus, but also Escherichia coli; and for physical objects, we used silver as main metal but also other metals (copper, cadmium and nickel) for comparison. The main objectives are: 1- to study the impact and the mechanisms of toxicity of these metallic ions/NPs on the bacterial respiratory and photosynthesis metabolisms. 2- To identify the bacterial genes involved in response to excess silver. 3- To study the internalization and interaction of metals ions and NPs within biological membranes. The results showed that we were able to identify, both in vitro and in vivo, specific targets of Ag⁺ and Cu²⁺ ions within the membrane of bacteria. This include complexes involved in photosynthesis, but also complexes involved in respiration. Ag⁺ and Cu²⁺ were shown to specificaly target a solvent exposed bacteriochlorophyll in the light harvesting antennae of the photosystem. This also presents, in our knowledge, the first direct evidence of silver ions damages to membrane proteins involved in these metabolisms. We also carried out a microscopy (AFM/ SEM) comparative study of the effect of Ag⁺ ions or Ag-NPs synthesized in our laboratory, on the bacterial cell morphology
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Moulton, Jon Daniel. "Photoadaptation Rate of Synechococcus WH7803 Cultures at Two Iron Concentrations". PDXScholar, 1998. https://pdxscholar.library.pdx.edu/open_access_etds/3070.
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The marine cyanobacterium Synechococcus WH7803 adapts to changes in light intensity by changing its photosynthetic physiology. This work is a study o f the rate o f photoadaptation of Synechococcus WH7803 in laboratory cultures. Cultures were shifted from constant 8 µEm-2s-1 light to constant 80 µEm-2s-1 light, from constant 80 µEm-2s-1 light to 8 µEm-2s-1 light and from different light regimes to a single fluctuating light regime. The response of high iron cultures grown in modified aquil culture medium at 5*10-6M Fe was compared with the response of low iron cultures grown in modified aquil medium at 1*10-6M Fe. Cultures were assayed every 2 days for at least 10 days, assaying cell population density by fluorescence microscopy, chlorophyll a by spectrophotometry of acetone extracts, total protein by the bicinchoninic acid method, and photosynthesis vs. irradiance (P vs. I) response by H14CO3 uptake at 10 light intensities.
Iron nutrition did not strongly affect the rate of photoadaptation as determined from the slopes of P vs. I curves as light approaches zero (the parameter called alpha). The rate of chlorophyll a synthesis was the parameter most strongly affected by iron nutrition, slowing in restricted iron medium. Based on alpha per cell, the adaptation time to the shift from constant 8 µEm-2s -1 light to constant 80 µEm-2s -1 light was less than 2 days. Based on other culture parameters the time to complete adaptation may be closer to 8 days. Based on alpha per cell, the adaptation time to the shift from constant 80 µEm-2s -1 light to constant 8 µEm-2s -1 light was on the order of 2 days. Based on other culture parameters the time to complete adaptation may exceed 10 days.
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Erculiani, Marco. "Atmosphere in a test tube: laboratory investigations about exoplanet atmospheres". Doctoral thesis, Università degli studi di Padova, 2015. http://hdl.handle.net/11577/3424370.
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The aim of this thesis is to understand if cyanobacteria, grown on an Earth-like planet orbiting around the habitable zone of an M star can survive and use the light coming from the star in a fruitful way, in particular analyzing their gaseous by-products. The organisms chosen usually don't have photopigments capable to photosynthesize the NIR part of the radiation, but can modify their photosynthetic apparatus in order to adapt to different light conditions if exposed in NIR light conditions, producing chlorophyll d and f. The two bacteria highlighted for our purpose are Chlorogloeopsis fritschii and Cyanobacterium Aponinum. The first is known to be able to change its photosynthetic apparatus to cope with new radiation conditions. In particular is capable to generate chlorophyll d and f if exposed to NIR light (720 nm). This feature is call FarLip acclimation. The second bacterium is a well known bacterium but no one has ever tried to understand if it has the same capability. Efforts have been done in order to find the best culture medium and the best growth conditions of temperature and pH. In order to understand how photosynthetic life can handle different radiation doses we ideated and realized a novel and pioneering LED radiation source with dynamical features. Its wavelength intervals (365nm-940nm) overlap the limits of photosynthetic pigment absorption range (280-850 nm) of most common photosynthetic bacteria. Our simulator is composed by an array of 25 different channels corresponding to 25 different wavelengths. Each channel can host a maximum of about 15 LEDs. This simulator has been built thinking to modularity. In fact it is endowed by a mosaic of circuit boards arranged in a pie-chart shape, on the surface of which will be welded the LEDs. This solution allows a rapid change of the damaged LEDs and an easy implementations with other wavelengths. This simulator is capable to reproduce the spectra of main sequence F, G, K and M stars as well as the most common commercial lamps within its wavelength intervals. The control system is composed by a Laptop which controls a LED box and an STS-VIS spectrograph from Ocean Optics with cosine corrector. The first system generate the best fit of the input spectrum and give information to the simulator on how to reproduce it. The spectrometer has the task to control the goodness of the fit and, by means of a closed loop system, to adjust it tuning the LED's power in real time. The stellar simulator bas been subjected to several tests. The power emanated from the radiation source has been estimated to be 106.22 W while the thermal power has been calculated to be 434.05 W. The stellar simulator have been characterized in flux, analyzing the radiation at different distances from the device, from the exit of the source up to 25 cm. Then uniformity measurements have been done, analyzing the flux on a distance of 6.5 cm from the centre. Finally, I calculated the absorption of the optics of the radiation source analyzing the spectra coming out from the stellar simulator and compared it with respect to the spectrum of the single LEDs. In order to lodge the bacteria we built new concept incubator made of a stainless steel cell with the potential to flux a desired gaseous mixture inside it and fill the cell with the desired gas mixture. Four wedged optical windows opens on the lateral surface and needs to allow the oxygen and carbon dioxide concentration inside by means of a Tunable Diode Laser Absorption Spectroscopy (TDLAS) system. The cell is topped by a BOROFLOAT uncoated window to collect the light from the stellar simulator. The cell has been characterized in void and oxygen and carbon dioxide detecting limits have been found. During the experiment, bacteria have been grown in white light conditions at for 24 days at 20 micromol photons/m^2/s and at 30°C in order to understand the growth times and the behaviour in optimal conditions.
After that, a new growth experiment have been performed by growing both cyanobacteria species at 30°C and 20 micromol photons/m^2/s and oxymetric measurements have been done after 6 days from the culture start, thus during their exponential growth phases. Then, for the main part of the experiment, eight samples have been used. Two samples of Cyanobacterium aponinum have been grown at 20 micromol photons/m^2/s in white light for 6 days and then at 100 micromol photons/m^2/s for the residual 3 days in white light. Two samples of Chlorogloeopsis fritschii have been grown at 20 micromol photons/m^2/s for 6 days in white light and then at 100 micromol photons/m^2/s for the residual 3 days in white light. Two samples of Cyanobacterium aponinum have been grown at 20 micromol photons/m^2/s for 6 days in white light and then at 100 micromol photons/m^2/s for the residual 3 days using the radiation spectrum of an M7 type star. Two samples of Chlorogloeopsis fritschii have been grown at 20 micromol photons/m^2/s for 6 days in white light and then at 100 micromol photons/m^2/s for the residual 3 days using the radiation spectrum of an M7 type star. The temperature has been kept at 30°C for the samples not exposed to M7 light and at a temperature oscillating from 35°C to 38°C for the samples exposed to M7 light. The higher environmental temperature under the stellar simulator has been due to the over-heating of the LEDs. During the 3 days of different exposure measurements of optical density have been done in order to collect data about the different growth curves. Moreover, O2 production have been calculated for each sample. Finally, a chromatic response have been done, in order to understand if the colour would reflect the vitality of the bacteriaLo scopo di questa tesi è quello di capire come dei cianobatteri, cresciuti su un pianeta di tipo terrestre orbitante attorno alla zona di abitabilità di una stella M possano sopravvivere ed usare la luce proveniente dalla stella stessa in modo fruttuoso per la loro esistenza. In particolare ci focalizzeremo sullo studio dei gas da essi prodotti. Gli organismi scelti non hanno pigmenti in grado di fotosintetizzare la parte NIR dello spettro di radiazione, ma riescono a modificare il loro apparato fotosintetico per far fronte alle nuove condizioni di luce, se esposti a luce NIR, producendo clorofilla d ed f. I due batteri scelti per i nostri esperimenti sono Chlorogloeopsis fritschii e Cyanobacterium Aponinum. Il primo batterio è certamente in grado di variare il suo apparato fotosintetico in differenti situazioni luminose. In particolare è in grado di produrre clorofilla e ed f se esposto a luce NIR (720 nm). Questa proprietà si chiama acclimatamento FarLip. Il secondo batterio è è abbastanza noto ma non è stata ancora studiata la sua predisposizione a questo tipo di pratica. Per questi batteri sono stati ricercati i terreni di coltura, di temperatura e pH che meglio permettessero il loro sviluppo. Per capire come il foto-acclimatamento possa aver luogo abbiamo ideato e realizzato un nuovo tipo di sorgente a LED con peculiarità dinamiche. L'intervallo di lunghezze d'onda che copre (365nm-940nm) si sovrappone ai limiti di assorbimento dei pigmenti fotosintetici (280-850 nm) dei più comuni batteri. Il simulatore è composto da 25 differenti canali corrispondenti a 25 differenti lunghezze d'onda. Ogni canale può ospitare un massimo di 15 LED. Il simulatore come detto è stato concepito secondo il concetto di modularità. Infatti è composto da un mosaico di piastre in corma circolare divisa a spicchi e su ognuna di tali piastre sono saldati i LED. Questa soluzione permette di cambiare rapidamente i LED danneggiati e permette una facile implementazione con altre lunghezze d'onda. Il simulatore stellare è in grado di riprodurre lo spettro di varie stelle di sequenza principale, F, G, K e M e molte delle più comuni lampade. Il sistema di controllo è composto da un PC che ha il compito di gestire i LED e da uno spettrometro con relativo correttore di coseno che STS-VIS della ditta Ocean Optics. Il PC genera il miglior fit dello spettro da ricreare con l'illuminatore e lgi da informazioni su come riprodurlo. Lo spettrometro invece controlla la bontà del fit ed attraverso un sistema a circuito chiuso, regola la luminosità dei LED in tempo reale. Abbiamo fatto dei test per verificare il corretto funzionamento del simulatore e stimato la potenza totale emanata, 106.22 W e quella termica, 434.05 W. Inoltre la nostra sorgente di radiazione è stata caratterizzata in flusso, analizzando la radiazione a diverse distanze, dalla bocca di apertura fino a 25 cm da essa. Poi sono state fatte misure di uniformità del flusso entro 6.5 cm dal centro. Infine è stato calcolato l'assorbimento dovuto alle ottiche frapposte fra i LED e i campioni. Per alloggiare i batteri abbiamo ideato e costruito in incubatore in acciaio inox con la possibilità di avere un continuo flussaggio di gas o di essere riempita con una miscela desiderata. Sui lati si aprono quattro finestre ottiche che servono per permettere la misura di concentrazione di ossigeno e di anidride carbonica all'interno attraverso un sistema laser chiamato Tunable Diode Laser Absorption Spectroscopy (TDLAS). L'incubatore è dotato anche di una finestra superiore in borosilicato per permettere alla luce di entrarvi. La cella è stata caratterizzata termicamente e sono stati calcolati le quantità minime osservabili sia di ossigeno che di anidride carbonica. Durante la prima fase dell'esperimento, i batteri selezionati sono stati fatti crescere per 24 giorni Durante l'esperimento, i batteri sono stati fatti crescere a 24 days at 20 micromol fotoni/m^2/s e a 30 °C per costruire le curve di crescita ed il loro comportamento in condizioni ottimali. Dopo ciò, è stato condotto un secondo esperimento facendo crescere entrambe se specie di cianobatteri a 30°C e 20 micromol fotoni/m^2/s in luce bianca ed acquisendo dopo 6 giorni le misure di produttività di ossigeno durante la fase esponenziale. Passati sei giorni sono stati ripartite otto colture, quattro di Cyanobacterium aponinum e quattro di Chlorogloeopsis fritschii. Due colture di Cyanobacterium aponinum sono state fattie crescere prima a micromol fotoni/m^2/s per sei giorni e poi a 100 micromol fotoni/m^2/s per altri tre giorni, sempre in luce bianca. La stessa cosa è stata fatta per due campioni di Chlorogloeopsis fritschii. Due colture di Cyanobacterium aponinum sono state fattie crescere prima a micromol fotoni/m^2/s per sei giorni e poi a 100 micromol fotoni/m^2/s per altri tre giorni,con una radiazione che simulava quella di una stella di tipo M7 incidente su un pianeta terrestre. La stessa cosa è stata fatta per Chlorogloeopsis fritschii. La temperatura è stata mantenuta a 30°C per i campioni in luce bianca e fra 35°C e 38°C per gli esemplari illuminati con luce M7. La maggior temperatura nel secondo caso è stata dovuta al calore prodotto dai LED. Durante i tre giorni in cui i campioni sono stati sottoposti a 100 micromol fotoni/m^2/s sono state prese misure di densità ottica e calcolate le curve di crescita. Inoltre per ogni campione è stata calcolata la produzione di ossigeno. Infine i campioni sono stati analizzati anche dal punto di vista del cromatismo per capire come il loro colore fosse collegato alla vitalità
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Babatunde, Oluwaseun Oyeniyi. "Exploring the potential of Rhodobacter sphaeroides in photodynamic therapy of tumors". Bowling Green State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1624793446693196.
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Babatunde, Oluwaseun Oyeniyi. "Exploring the potential of Rhodobacter sphaeroides in photodynamic therapy of tumors". Bowling Green State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=bgsu1624793446693196.
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Jun, Daniel Young. "Recombinant expression and band-gap engineering of the bacterial photosynthetic reaction centre". Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/61292.
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The Rhodobacter sphaeroides photosynthetic reaction centre (RC) is a pigment-protein complex that efficiently captures and converts photon energy into a charge-separated state. Given the conversion efficiency and the high electric potential of the electron, the major focus of my project was to deliver/extract electrons to/from various cofactors along the charge-separation pathway in the RC, including the special pair of bacteriochlorophylls (P), the bacteriopheophytin (HA), the primary quinone (QA), and the secondary quinone (QB). An over-expression system was created to produce RCs, using the R. sphaeroides RCx strain, pIND4 plasmid, a modified culture medium, and changes to growth conditions. These changes resulted in a 35-fold increase in protein levels compared to the previous system. To extract electrons from the quinone region of the RC, this region was made more accessible to the solvent by deleting portions of the H subunit cytoplasmic globular domain. The results indicated that the truncated RC mutants assembled stably and thereby reduced the electron transfer distance between the quinone and an external electron acceptor. Photochronoamperometry measurements on mutant RCs designed to test the feasibility of delivering electrons from an electrode to P showed photocurrent generation and direction that were consistent with the binding of the RC P-side to the electrode surface. Similar experiments on the feasibility of extracting electrons from HA, QA and QB, for delivery to highly ordered pyrolytic graphite (HOPG) or gold electrodes, also showed photocurrent generation and direction consistent with the binding of the RC HA-side or Q-side to the electrode surface. Finally, the thermal stability of complexes was studied by in vivo addition of light harvesting complex 1 (LH1) from the thermophile Thermochromatium tepidum to the RC. A hybrid core complex consisting of an R. sphaeroides RC surrounded by T. tepidum TLH1 conferred greater tolerance to thermal energies, compared to the analogous R. sphaeroides RC-LH1 core complex, at temperatures up to 70 °C. The combination of these results show that, in principle, the RC can be modified to extract electrons at different energy levels, or band gaps, with possible applications in heat-stabile biohybrid solar cell technologies.Science, Faculty of
Microbiology and Immunology, Department of
Graduate
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Nogi, Terukazu. "Structural studies of bacterial photosynthetic reaction center : thermostability of membrane protein and electron transfer". 京都大学 (Kyoto University), 2001. http://hdl.handle.net/2433/150853.
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