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D Jun, H S Dhupar, A Mahmoudzadeh, F Duong, J D W Madden, J T Beatty
We address a challenge in the engineering of proteins to redirect electron transfer pathways, using the bacterial photosynthetic reaction centre (RC) pigment-protein complex. Direct electron transfer is shown to occur from the QA quinone of the Rhodobacter sphaeroides RC containing a truncated H protein and bound on the quinone side to a gold electrode. In previous reports of binding to the quinone side of the RC, electron transfer has relied on the use of a soluble mediator between the RC and an electrode, in part because the probability of QB quinone reduction is much greater than that of direct electron transfer through the large cytoplasmic domain of the H subunit, presenting a ~ 25 Å barrier...
March 9, 2018: Photosynthesis Research
Lu Cai, Tong-Bin Chen, Sheng-Wei Zheng, Hong-Tao Liu, Guo-Di Zheng
Sewage sludge biodrying is a waste treatment method that uses bio-heat generated from organic degradation to remove moisture from sewage sludge. Lignocellulose and carbohydrate decomposition is important when assessing biodrying performance. This study investigated lignocellulose and carbohydrate decomposition, and the potential microbial functions during biodrying. We determined the lignocellulose and carbohydrate contents, assayed related enzyme activity, performed a complete metagenomic study on sewage sludge biodrying material during the thermophilic phase, annotated potential genetic function involved in the decomposition, and summarized the key metabolic pathways...
February 28, 2018: Chemosphere
Marcia Ortega-Ramos, Daniel P Canniffe, Matthew Radle, C Neil Hunter, Donald A Bryant, John H Golbeck
Engineering photosynthetic bacteria to utilize a heterologous reaction center that contains a different (bacterio) chlorophyll could improve solar energy conversion efficiency by allowing cells to absorb a broader range of the solar spectrum. One promising candidate is the homodimeric type I reaction center from Heliobacterium modesticaldum. It is the simplest known reaction center and uses bacteriochlorophyll (BChl) g, which absorbs in the near-infrared region of the spectrum. Like the more common BChls a and b, BChl g is a true bacteriochlorin...
February 26, 2018: Biochimica et Biophysica Acta
Bahia Khalfaoui-Hassani, Hongjiang Wu, Crysten E Blaby-Haas, Yang Zhang, Federica Sandri, Andreia F Verissimo, Hans-Georg Koch, Fevzi Daldal
Cytochrome c oxidases are members of the heme-copper oxidase superfamily. These enzymes have different subunits, cofactors, and primary electron acceptors, yet they all contain identical heme-copper (CuB ) binuclear centers within their catalytic subunits. The uptake and delivery pathways of the CuB atom incorporated into this active site, where oxygen is reduced to water, are not well understood. Our previous work with the facultative phototrophic bacterium Rhodobacter capsulatus indicated that the copper atom needed for the CuB site of cbb 3 -type cytochrome c oxidase ( cbb 3 -Cox) is imported to the cytoplasm by a major facilitator superfamily-type transporter, CcoA...
February 27, 2018: MBio
Qingfeng Li, Tao Peng, Gabriele Klug
BACKGROUND: A major role of the PhyR-NepR-σ(EcfG) cascade in the general stress response was demonstrated for some bacterial species and considered as conserved in Alphaproteobacteria. The σ(EcfG) factor activates its target genes in response to diverse stresses and NepR represents its anti-sigma factor. PhyR comprises a response regulator domain and a sigma factor domain and acts as anti-sigma factor antagonist. The facultative phototrophic alphaproteobacterium Rhodobacter sphaeroides harbours a PhyR homolog in the same genomic context as found in other members of this class...
February 27, 2018: BMC Microbiology
Saroj Poudel, Daniel R Colman, Kathryn R Fixen, Rhesa N Ledbetter, Yanning Zheng, Natasha Pence, Lance C Seefeldt, John W Peters, Caroline S Harwood, Eric S Boyd
Nitrogenase catalyzes the reduction of dinitrogen (N2 ) using low potential electrons from ferredoxin (Fd) or flavodoxin (Fld) through an ATP dependent process. Since its emergence in an anaerobic chemoautotroph, this oxygen (O2 ) sensitive enzyme complex has evolved to operate in a variety of genomic and metabolic backgrounds including those of aerobes, anaerobes, chemotrophs, and phototrophs. However, whether pathways of electron delivery to nitrogenase are influenced by these different metabolic backgrounds is not well understood...
February 26, 2018: Journal of Bacteriology
Wataru Matsuura, Shinichi Harada, Keyue Liu, Masahiro Nishibori, Shogo Tokuyama
We have previously showed that spinal high-mobility group box-1 (HMGB1) plays an important role in the induction of central post-stroke pain (CPSP). It has been reported that HMGB1 exacerbates inflammation and pain via TLR4 or RAGE. Furthermore, the relationship between glial cells, such as microglia and astrocytes, involved in pain exacerbation and HMGB1 has also attracted attention. In this study, we investigated whether the interaction between spinal glial cells and HMGB1 signaling, including its receptors TLR4 or RAGE, is directly involved in the induction of CPSP...
February 21, 2018: Brain Research
Chih-Yu Chen, Teh-Hua Tsai, Chih-Hao Chang, Chih-Fang Tseng, Shih-Yun Lin, Ying-Chien Chung
The effectiveness of an airlift reactor system in simultaneously removing hydrogen sulfide (H2 S) and ammonia (NH3 ) from synthetic and actual waste gases was investigated. The effects of various parameters, including the ratio of inoculum dilution, the gas concentration, the gas retention time, catalyst addition, the bubble size, and light intensity, on H2 S and NH3 removal were investigated. The results revealed that optimal gas removal could be achieved by employing an activated inoculum, using a small bubble stone, applying reinforced fluorescent light, adding Fe2 O3 catalysts, and applying a gas retention time of 20 s...
February 21, 2018: Journal of Environmental Science and Health. Part A, Toxic/hazardous Substances & Environmental Engineering
Peter P Knox, Vladimir V Gorokhov, Boris N Korvatovskiy, Eugene P Lukashev, Sergey N Goryachev, Vladimir Z Paschenko, Andrew B Rubin
The temperature dependencies of the rate of dark recombination of separated charges between the photoactive bacteriochlorophyll and the primary quinone acceptor (QA) in photosynthetic reaction centers (RCs) of the purple bacteria Rhodobacter sphaeroides (Rb. sphaeroides) were investigated. Measurements were performed in water-glycerol and trehalose environments after freezing to -180 °C in the dark and under actinic light with subsequent heating. Simultaneously, the RC tryptophanyl fluorescence lifetime in the spectral range between 323 and 348 nm was measured under these conditions...
February 6, 2018: Journal of Photochemistry and Photobiology. B, Biology
Jinxian Liu, Cui Li, Juhui Jing, Pengyu Zhao, Zhengming Luo, Miaowen Cao, Zhuanzhuan Ma, Tong Jia, Baofeng Chai
Environmental gradient have strong effects on community assembly processes. In order to reveal the effects of alkaline mine drainage (AlkMD) on bacterial and denitrifying bacterial community compositions and diversity in tailings reservoir, here we conducted an experiment to examine all and core bacterial taxa and denitrifying functional genes's (nirS, nirK, nosZΙ) abundance along a chemical gradient in tailings water in Shibahe copper tailings in Zhongtiaoshan, China. Differences in bacterial and denitrifying bacterial community compositions in different habitats and their relationships with environmental parameters were analyzed...
January 9, 2018: Water Research
Juntai Liu, Vincent M Friebe, David J K Swainsbury, Lucy I Crouch, David A Szabo, Raoul N Frese, Michael R Jones
Reaction centre/light harvesting proteins such as the RCLH1X complex from Rhodobacter sphaeroides carry out highly quantum-efficient conversion of solar energy through ultrafast energy transfer and charge separation, and these pigment-proteins have been incorporated into biohybrid photoelectrochemical cells for a variety of applications. In this work we demonstrate that, despite not being able to support normal photosynthetic growth of Rhodobacter sphaeroides, an engineered variant of this RCLH1X complex lacking the PufX protein and with an enlarged light harvesting antenna is unimpaired in its capacity for photocurrent generation in two types of bio-photoelectrochemical cells...
January 24, 2018: Faraday Discussions
Xing-Long Yang, Jing-Dong Zhang, Lian Duan, Huan-Gui Xiong, Yan-Ping Jiang, Hou-Cheng Liang
Microglia activation and white matter injury coexist after repeated episodes of mild brain trauma and ischemic stroke. Axon degeneration and demyelination can activate microglia; however, it is unclear whether early microglia activation can impair the function of white matter tracts and lead to injury. Rat corpus callosum (CC) slices were treated with lipopolysaccharide (LPS) or LPS + Rhodobacter sphaeroides (RS)-LPS that is a toll-like receptor 4 (TLR-4) antagonist. Functional changes reflected by the change of axon compound action potentials (CAPs) and the accumulation of β-amyloid precursor protein (β-APP) in CC nerve fibers...
November 1, 2017: Journal of Biomedical Research
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
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