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Paul Kaufmann, Benjamin R Duffus, Biljana Mitrova, Chantal Iobbi-Nivol, Christian Teutloff, Manfred Nimtz, Lothar Jänsch, Ulla Wollenberger, Silke Leimkühler
The well-studied enterobacterium Escherichia coli present in the human gut is able to reduce TMAO to trimethylamine (TMA) during anaerobic respiration. The TMAO reductase TorA is a monomeric, bis-molybdopterin guanine dinucleotide (bis-MGD) cofactor-containing enzyme belonging to the dimethylsulfoxide (DMSO) reductase family of molybdoenzymes. We report on a system for the in vitro reconstitution of TorA with molybdenum cofactors (Moco) from different sources. Higher TMAO reductase activities for TorA were obtained when using Moco-sources containing a sulfido ligand at the molybdenum atom...
January 15, 2018: Biochemistry
Weihua Peng, Xiaomin Li, Jingxiang Song, Wei Jiang, Yingying Liu, Wenhong Fan
Bioremediation using microorganisms is a promising technique to remediate soil contaminated with heavy metals. In this study, Rhodobacter sphaeroides was used to bioremediate soils contaminated with cadmium (Cd) and zinc (Zn). The study found that the treatment reduced the overall bioavailable fractions (e.g., exchangeable and carbonate bound phases) of Cd and Zn. More stable fractions (e.g., Fe-Mn oxide, organic bound, and residual phases (only for Zn)) increased after bioremediation. A wheat seedling experiment revealed that the phytoavailability of Cd was reduced after bioremediation using R...
January 6, 2018: Chemosphere
Ajoy Roy, Avishek Dutta, Siddhartha Pal, Abhishek Gupta, Jayeeta Sarkar, Ananya Chatterjee, Anumeha Saha, Poulomi Sarkar, Pinaki Sar, Sufia K Kazy
Scope for developing an engineered bioremediation strategy for the treatment of hydrocarbon-rich petroleum refinery waste was investigated through biostimulation and bioaugmentation approaches. Enhanced (46-55%) total petroleum hydrocarbon (TPH) attenuation was achieved through phosphate, nitrate or nitrate+phosphate amendment in the sludge with increased (upto 12%) abundance of fermentative, hydrocarbon degrading, sulfate-reducing, CO2-assimilating and methanogenic microorganisms (Bacillus, Coprothermobacter, Rhodobacter, Pseudomonas, Achromobacter, Desulfitobacter, Desulfosporosinus, T78, Methanobacterium, Methanosaeta, etc)...
January 3, 2018: Bioresource Technology
Tatyana Laurinavichene, Darya Tekucheva, Kestutis Laurinavichius, Anatoly Tsygankov
In this study, distillery wastewater was treated by dark fermentation or photofermentation alone, and by sequential dark and photofermentation processes using anaerobic saccharolytic consortium and purple nonsulfur bacteria. Combination of dark and photofermentation resulted in the maximal H2 yield of 17.6L/L of distillery waste with chemical oxygen demand 40g/L. It is equivalent to 205kJ/L distillery wastewater and corresponds to recovery of approximately 4-8% of energy consumed during ethanol production. Optimal performance of photofermentation was observed at 20% concentration of pre-fermented distillery waste...
March 2018: Enzyme and Microbial Technology
Josué Pacheco, Dimitri Niks, Russ Hille
We have examined the kinetic and spectroscopic properties of a tungsten-substituted form of DMSO reductase from Rhodobacter sphaeroides, an enzyme that normally possesses molybdenum. Partial reduction with sodium dithionite yields a well-resolved W(V) EPR signal of the so-called "high-g split" type that exhibits markedly greater g-anisotropy than the corresponding Mo(V) signal of the native form of the enzyme, with the g values shifted to higher magnetic field by as much as Δgave = 0.056. Deuteration of the enzyme confirms that the coupled proton is solvent-exchangeable, allowing us to accurately simulate the tungsten hyperfine coupling...
January 3, 2018: Journal of Biological Inorganic Chemistry: JBIC
Hong Chen, Xuhao Zhao, Yuying Cheng, Mingji Jiang, Xiang Li, Gang Xue
Simultaneous nitrification and denitrification (SND) is a promising single-reactor biological nitrogen-removal method. Activated sludge with and without iron scrap supplementation (Sludge-Fe and Sludge-C, respectively) was acclimated under aerobic condition. The total nitrogen (TN) content of Sludge-Fe substantially decreased from 25.0±1.0 to 11.2±0.4 mg/L, but Sludge-C did not show the TN-removal capacity. Further investigations excluded a chemical reduction of NO3--N by iron and a decrease of NH4+-N by microbial assimilation, and the contribution of SND was verified...
January 3, 2018: Environmental Science & Technology
Takayuki Shimizu, Kouhei Horiguchi, Yui Hatanaka, Shinji Masuda, Keizo Shimada, Katsumi Matsuura, Shin Haruta
Growth inhibition of Rhodobacter sphaeroides f. sp. denitrificans IL106 by nitrite under anaerobic-light conditions became less pronounced when the gene encoding nitrite reductase was deleted. Growth of another deletion mutant of the genes encoding nitric oxide reductase was severely suppressed by nitrite. Our results suggest that nitrite reductase increases the sensitivity to nitrite through the production of nitric oxide.
January 3, 2018: Bioscience, Biotechnology, and Biochemistry
David J K Swainsbury, Matthew S Proctor, Andrew Hitchcock, Michaël L Cartron, Pu Qian, Elizabeth C Martin, Philip J Jackson, Jeppe Madsen, Steven P Armes, C Neil Hunter
Intracytoplasmic vesicles (chromatophores) in the photosynthetic bacterium Rhodobacter sphaeroides represent a minimal structural and functional unit for absorbing photons and utilising their energy for the generation of ATP. The cytochrome bc1 complex (cytbc1) is one of the four major components of the chromatophore alongside the reaction centre-light harvesting 1-PufX core complex (RC-LH1-PufX), the light-harvesting 2 complex (LH2), and ATP synthase. Although the membrane organization of these complexes is known, their local lipid environments have not been investigated...
December 29, 2017: Biochimica et Biophysica Acta
Gábor Sipka, Mariann Kis, Péter Maróti
Mercuric contamination of aqueous cultures results in impairment of viability of photosynthetic bacteria primarily by inhibition of the photochemistry of the reaction center (RC) protein. Isolated reaction centers (RCs) from Rhodobacter sphaeroides were exposed to Hg2+ ions up to saturation concentration (~ 103 [Hg2+]/[RC]) and the gradual time- and concentration-dependent loss of the photochemical activity was monitored. The vast majority of Hg2+ ions (about 500 [Hg2+]/[RC]) had low affinity for the RC [binding constant Kb ~ 5 mM-1] and only a few (~ 1 [Hg2+]/[RC]) exhibited strong binding (Kb ~ 50 μM-1)...
December 28, 2017: Photosynthesis Research
Rakesh Pandey, Judith P Armitage, George H Wadhams
BACKGROUND: Photosynthetic (PS) gene expression in Rhodobacter sphaeroides is regulated in response to changes in light and redox conditions mainly by PrrB/A, FnrL and AppA/PpsR systems. The PrrB/A and FnrL systems activate the expression of them under anaerobic conditions while the AppA/PpsR system represses them under aerobic conditions. Recently, two mathematical models have been developed for the AppA/PpsR system and demonstrated how the interaction between AppA and PpsR could lead to a phenotype in which PS genes are repressed under semi-aerobic conditions...
December 28, 2017: BMC Systems Biology
Anita Loeschcke, Dennis Dienst, Vera Wewer, Jennifer Hage-Hülsmann, Maximilian Dietsch, Sarah Kranz-Finger, Vanessa Hüren, Sabine Metzger, Vlada B Urlacher, Tamara Gigolashvili, Stanislav Kopriva, Ilka M Axmann, Thomas Drepper, Karl-Erich Jaeger
Cyclic triterpenes constitute one of the most diverse groups of plant natural products. Besides the intriguing biochemistry of their biosynthetic pathways, plant triterpenes exhibit versatile bioactivities, including antimicrobial effects against plant and human pathogens. While prokaryotes have been extensively used for the heterologous production of other classes of terpenes, the synthesis of cyclic triterpenes, which inherently includes the two-step catalytic formation of the universal linear precursor 2,3-oxidosqualene, is still a major challenge...
2017: PloS One
Kata Hajdu, Ateeq Ur Rehman, Imre Vass, László Nagy
Photosynthetic reaction center proteins (RCs) are the most efficient light energy converter systems in nature. The first steps of the primary charge separation in photosynthesis take place in these proteins. Due to their unique properties, combining RCs with nano-structures promising applications can be predicted in optoelectronic systems. In the present work RCs purified from Rhodobacter sphaeroides purple bacteria were immobilized on multiwalled carbon nanotubes (CNTs). Carboxyl-and amine-functionalised CNTs were used, so different binding procedures, physical sorption and chemical sorption as well, could be applied as immobilization techniques...
December 26, 2017: Materials
Holly L Sewell, Anne-Kristin Kaster, Alfred M Spormann
The deep marine subsurface is one of the largest unexplored biospheres on Earth and is widely inhabited by members of the phylum Chloroflexi In this report, we investigated genomes of single cells obtained from deep-sea sediments of the Peruvian Margin, which are enriched in such Chloroflexi 16S rRNA gene sequence analysis placed two of these single-cell-derived genomes (DscP3 and Dsc4) in a clade of subphylum I Chloroflexi which were previously recovered from deep-sea sediment in the Okinawa Trough and a third (DscP2-2) as a member of the previously reported DscP2 population from Peruvian Margin site 1230...
December 19, 2017: MBio
Migun Shakya, Shannon M Soucy, Olga Zhaxybayeva
Several bacterial and archaeal lineages produce nanostructures that morphologically resemble small tailed viruses, but, unlike most viruses, contain apparently random pieces of the host genome. Since these elements can deliver the packaged DNA to other cells, they were dubbed gene transfer agents (GTAs). Because many genes involved in GTA production have viral homologs, it has been hypothesized that the GTA ancestor was a virus. Whether GTAs represent an atypical virus, a defective virus, or a virus co-opted by the prokaryotes for some function, remains to be elucidated...
July 2017: Virus Evolution
Tatyana Laurinavichene, Kestutis Laurinavichius, Evgeny Shastik, Anatoly Tsygankov
OBJECTIVES: To prove the possibility of efficient starch photofermentation in co-culture of heterotrophic and phototrophic bacteria over prolonged period. RESULTS: Repeated batch photofermentation of starch was demonstrated in co-culture Clostridium butyricum and Rhodobacter sphaeroides under microaerobic conditions. It continued 15 months without addition of new inoculum or pH regulation when using 4-5 g starch l-1 and 0.04 g yeast extract l-1. The complete degradation of starch without volatile fatty acids accumulation was shown in this co-culture...
November 30, 2017: Biotechnology Letters
Marcin Sarewicz, Łukasz Bujnowicz, Artur Osyczka
One of the less understood parts of the catalytic cycle of cytochrome bc1/b6f complexes is the mechanism of electronic bifurcation occurring within the hydroquinone oxidation site (Qo site). Several models describing this mechanism invoke a phenomenon of formation of an unstable semiquinone. Recent studies with isolated cytochrome bc1 or b6f revealed that a relatively stable semiquinone spin-coupled to the reduced Rieske cluster (SQ-FeS) is generated at the Qo site during the oxidation of ubi- or plastohydroquinone analogs under conditions of continuous turnover...
November 24, 2017: Biochimica et Biophysica Acta
Olga Rancova, Ryszard J Jankowiak, Darius Abramavicius
Spectroscopically relevant properties in photosynthetic reaction centers change during charge separation. In this work we focus on incorporation of the complete set of the environmental fluctuations in the modeling of the non-linear spectra of molecular aggregates. The model is applied in simulations of two-dimensional electronic spectra of a photosynthetic reaction center at low temperature (5K), where spectral lines are narrow, such that more features can be resolved. We show that vertical cross sections of the simulated two-dimensional spectra (with all populations in the lowest excited state) reveal transient hole-burned spectra excited resonantly within the B-band in agreement with experiment, thus providing new insight into environmental fluctuation parameters of Rhodobacter sphaeroides at low temperatures...
November 27, 2017: Journal of Physical Chemistry. B
Hendrik Mohrmann, Jovan Dragelj, Federico Baserga, Ernst-Walter Knapp, Sven T Stripp, Joachim Heberle
Retraction of 'The reductive phase of Rhodobacter sphaeroides cytochrome c oxidase disentangled by CO ligation' by Hendrik Mohrmann et al., Phys. Chem. Chem. Phys., 2017, DOI: .
November 21, 2017: Physical Chemistry Chemical Physics: PCCP
Emrah Sağır, Meral Yucel, Patrick C Hallenbeck
Hydrogen generation from complex substrates composed of simple sugars has the potential to mitigate future worldwide energy demand. The biohydrogen potential of a sequential microaerobic dark- and photo-fermentative system was investigated using immobilized Rhodobacter capsulatus JP91. Biological hydrogen production from glucose was carried out using a batch process and a bench-scale bioreactor. Response surface methodology with a Box-Behnken design was employed to optimize key parameters such as inoculum concentration, oxygen concentration, and glucose concentration...
November 9, 2017: Bioresource Technology
Eduardo Espiritu, Tien Le Olson, JoAnn C Williams, James P Allen
The ability of an artificial four-helix bundle Mn-protein, P1, to bind and transfer an electron to photosynthetic reaction centers from the purple bacterium Rhodobacter sphaeroides was characterized using optical spectroscopy. Upon illumination of reaction centers, an electron is transferred from P, the bacteriochlorophyll dimer, to QA, the primary electron acceptor. The P1 Mn-protein can bind to the reaction center and reduce the oxidized bacteriochlorophyll dimer, P+, with a dissociation constant of 1.2 µM at pH 9...
November 13, 2017: Biochemistry
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