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Sebastià Puig, Ramon Ganigué, Pau Batlle-Vilanova, M Dolors Balaguer, Lluís Bañeras, Jesús Colprim
This study reveals that reduction of carbon dioxide (CO2) to commodity chemicals can be functionally compartmentalized in bioelectrochemical systems. In the present example, a syntrophic consortium composed by H2-producers (Rhodobacter sp.) in the biofilm is combined with carboxidotrophic Clostridium species, mainly found in the bulk liquid. The performance of these H2-mediated electricity-driven systems could be tracked by the activity of a biological H2 sensory protein identified at cathode potentials between -0...
December 30, 2016: Bioresource Technology
Vincenzo Luongo, Anish Ghimire, Luigi Frunzo, Massimiliano Fabbricino, Giuseppe d'Antonio, Francesco Pirozzi, Giovanni Esposito
The aim of this work is to investigate the hydrogen and poly-β-hydroxybutyrate (PHB) production during the photofermentative treatment of the effluent from a dark fermentation reactor fed with the organic fraction of municipal solid waste. Two different inocula, an adapted culture of Rhodobacter sphaeroides AV1b and a mixed consortium of purple non sulphur bacteria have been investigated under the same operational conditions. Different hydrogen productivities of 364 and 559NmL H2 L(-1) were observed for the Rhodobacter sphaeroides and the mixed culture consortium tests, respectively: the consortium of PNSB resulted 1...
December 24, 2016: Bioresource Technology
Katie J Grayson, Kaitlyn M Faries, Xia Huang, Pu Qian, Preston Dilbeck, Elizabeth C Martin, Andrew Hitchcock, Cvetelin Vasilev, Jonathan M Yuen, Dariusz M Niedzwiedzki, Graham J Leggett, Dewey Holten, Christine Kirmaier, C Neil Hunter
Photosynthesis uses a limited range of the solar spectrum, so enhancing spectral coverage could improve the efficiency of light capture. Here, we show that a hybrid reaction centre (RC)/yellow fluorescent protein (YFP) complex accelerates photosynthetic growth in the bacterium Rhodobacter sphaeroides. The structure of the RC/YFP-light-harvesting 1 (LH1) complex shows the position of YFP attachment to the RC-H subunit, on the cytoplasmic side of the RC complex. Fluorescence lifetime microscopy of whole cells and ultrafast transient absorption spectroscopy of purified RC/YFP complexes show that the YFP-RC intermolecular distance and spectral overlap between the emission of YFP and the visible-region (QX) absorption bands of the RC allow energy transfer via a Förster mechanism, with an efficiency of 40±10%...
January 5, 2017: Nature Communications
Satarupa Bhaduri, Valentyn Stadnytskyi, Stanislav D Zakharov, S Saif Hasan, Łucas Bujnowicz, Marcin J Sarewicz, Sergei Savikhin, Artur Osyczka, William A Cramer
The intra-membrane cytochrome bc1 complex of the photosynthetic bacterium, Rhodobacter capsulatus, and the cytochrome b6f complex which functions in oxygenic photosynthesis, utilize two pairs of b-hemes in a symmetric dimer to accomplish proton-coupled electron transfer. The trans-membrane electron transfer pathway in each complex was identified through novel use of heme Soret band excitonic circular dichroism spectra, for which the responsible heme-heme interactions were determined from crystal structures...
December 29, 2016: Journal of Physical Chemistry. B
Virginia Montiel Corona, Sylvie Le Borgne, Sergio Revah, Marcia Morales
A Rhodobacter capsulatus strain and a photoheterotrophic culture (IZT) were cultivated to produce hydrogen under different light-dark cycles. A dark fermentation effluent (DFE) was used as substrate. It was found that IZT culture had an average cumulative hydrogen production (Paccum H2) of 1300±43mLH2L(-1) under continuous illumination and light-dark cycles of 30 or 60min. In contrast, R. capsulatus reduced its Paccum H2 by 20% under 30:30min light-dark cycles, but tripled its poly-β-hydroxybutyrate (PHB) content (308±2mgPHB gdw(-1)) compared to continuous illumination...
December 9, 2016: Bioresource Technology
Matt S A Wecker, Stephen E Beaton, Robert A Chado, Maria L Ghirardi
The cover image, by Maria L. Ghirardi et al., is based on the Article Development of a Rhodobacter capsulatus self-reporting model system for optimizing light-dependent, [FeFe]-hydrogenase-driven H2 production, DOI: 10.1002/bit.26076.
February 2017: Biotechnology and Bioengineering
Kamal Elkahlout, Siamak Alipour, Inci Eroglu, Ufuk Gunduz, Meral Yucel
In this study, agar immobilization technique was employed for biological hydrogen production using Rhodobacter capsulatus DSM 1710 (wild type) and YO3 (hup-mutant) strains in sequential batch process. Different agar and glutamate concentrations were tested with defined nutrient medium. Agar concentration 4% (w/v) and 4 mM glutamate were selected for bacterial immobilization in terms of rate and longevity of hydrogen production. Acetate concentration was increased from 40 to 60-100 and 60 mM gave best results with both bacterial strains immobilized in 4% (w/v) agar...
December 20, 2016: Bioprocess and Biosystems Engineering
Hongju Ma, Fan Zhang, Elisabeth Ignatz, Martin Suehnel, Peng Xue, Patrick Scheerer, LarsOliver Essen, Norbert Krauß, Tilman Lamparter
The (6-4) photolyases of the FeS-BCP group can be considered as the most ancient type among the large family of cryptochrome and photolyase flavoproteins. In contrast to other photolyases they contain an Fe-S cluster of unknown function, a DMRL chromophore, an interdomain loop which could interact with DNA, and a long C-terminal extension. We compared DNA repair and photoreduction of two members of the FeS-BCP family, Agrobacterium fabrum PhrB and Rhodobacter sphaeroides RsCryB, with a eukaryotic (6-4) photolyase from Ostreococcus, OsCPF, and a member of the class III CPD photolyases, PhrA from A...
December 19, 2016: Photochemistry and Photobiology
Jonathan Lo, Daniel G Olson, Sean Jean-Loup Murphy, Liang Tian, Shuen Hon, Anthony Lanahan, Adam M Guss, Lee R Lynd
The NfnAB (NADH-dependent reduced ferredoxin: NADP(+) oxidoreductase) and Rnf (ion-translocating reduced ferredoxin: NAD(+) oxidoreductase) complexes are thought to catalyze electron transfer between reduced ferredoxin and NAD(P)(+). Efficient electron flux is critical for engineering fuel production pathways, but little is known about the relative importance of these enzymes in vivo. In this study we investigate the importance of the NfnAB and Rnf complexes in Clostridium thermocellum for growth on cellobiose and Avicel using gene deletion, enzyme assays, and fermentation product analysis...
January 2017: Metabolic Engineering
José Hernandez-Valle, Clelia Domenzain, Javier de la Mora, Sebastian Poggio, Georges Dreyfus, Laura Camarena
: Rhodobacter sphaeroides is a α-proteobacterium that has two complete sets of flagellar genes. The fla1 set was acquired by horizontal transfer from an ancestral γ-proteobacterium and is the only set of flagellar genes that is expressed during growth under standard laboratory conditions. The products of these genes assemble a single, subpolar flagellum. In the absence of the Fla1 flagellum, a gain-of-function mutation in the histidine kinase CckA turns on the expression of the fla2 flagellar genes through the response regulator CtrA...
December 12, 2016: Journal of Bacteriology
Insung Na, Shelly DeForte, Bosko M Stojanovski, Gloria C Ferreira, Vladimir N Uversky
Heme biosynthesis, a complex, multistage, and tightly controlled process, starts with 5-aminolevulinate (ALA) production, which, in metazoa and certain bacteria, is a reaction catalyzed by 5-aminolevulinate synthase (ALAS), a pyridoxal 5'-phosphate (PLP)-dependent enzyme. Functional aberrations in ALAS are associated with several human diseases. ALAS can adopt open and closed conformations, with segmental rearrangements of a C-terminal, 16-amino acid loop and an α-helix regulating accessibility to the ALAS active site...
December 8, 2016: Journal of Biomolecular Structure & Dynamics
Emma Barahona, Emilio Jiménez-Vicente, Luis M Rubio
When produced biologically, especially by photosynthetic organisms, hydrogen gas (H2) is arguably the cleanest fuel available. An important limitation to the discovery or synthesis of better H2-producing enzymes is the absence of methods for the high-throughput screening of H2 production in biological systems. Here, we re-engineered the natural H2 sensing system of Rhodobacter capsulatus to direct the emission of LacZ-dependent fluorescence in response to nitrogenase-produced H2. A lacZ gene was placed under the control of the hupA H2-inducible promoter in a strain lacking the uptake hydrogenase and the nifH nitrogenase gene...
December 2, 2016: Scientific Reports
Emre M Ipekoğlu, Koray Göçmen, Mehmet T Öz, Muazzez Gürgan, Meral Yücel
Rhodobacter sphaeroides is a purple non-sulfur bacterium which photoheterotrophically produces hydrogen from organic acids under anaerobic conditions. A gene coding for putative chlorophyll a synthase (chlG) from cyanobacterium Prochlorococcus marinus was amplified by nested polymerase chain reaction and cloned into an inducible-expression plasmid which was subsequently transferred to R. sphaeroides for heterologous expression. Induced expression of chlG in R. sphaeroides led to changes in light absorption spectrum within 400-700 nm...
November 30, 2016: Journal of Basic Microbiology
Nadine Katzke, Andreas Knapp, Anita Loeschcke, Thomas Drepper, Karl-Erich Jaeger
Functional expression of genes from metagenomic libraries is limited by various factors including inefficient transcription and/or translation of target genes as well as improper folding and assembly of the corresponding proteins caused by the lack of appropriate chaperones and cofactors. It is now well accepted that the use of different expression hosts of distinct phylogeny and physiology can dramatically increase the rate of success. In the following chapter, we therefore describe tools and protocols allowing for the comparative heterologous expression of genes in five bacterial expression hosts, namely Escherichia coli, Pseudomonas putida, Bacillus subtilis, Burkholderia glumae, and Rhodobacter capsulatus...
2017: Methods in Molecular Biology
Ju-Yong Park, Yang-Hoon Kim, Jiho Min
In Rhodobacter sphaeroides, carbonic anhydrase (CA; EC is a zinc-containing metalloenzyme that catalyzes the reversible hydration of CO2 to HCO3(-) while phosphoenolpyruvate carboxylase (PEPC;, an enzyme involved in the carbon metabolism that catalyzed the fixation of CO2 to PEP, is a key factor for biological fixation of CO2 and enhances the production of organic compounds. In this study, the recombinant R. sphaeroides with highly-expressed CA was developed based on a surface displayed system of CA (pJY-OmpCA) on the outer membrane of R...
January 2017: Enzyme and Microbial Technology
Roberto Borghese, Marco Brucale, Gianuario Fortunato, Massimiliano Lanzi, Alessio Mezzi, Francesco Valle, Massimiliano Cavallini, Davide Zannoni
The toxic oxyanion tellurite (TeO3(2-)) is acquired by cells of Rhodobacter capsulatus grown anaerobically in the light, via acetate permease ActP2 and then reduced to Te(0) in the cytoplasm as needle-like black precipitates. Interestingly, photosynthetic cultures of R. capsulatus can also generate Te(0) nanoprecipitates (TeNPs) outside the cells upon addition of the redox mediator lawsone (2-hydroxy-1,4-naphtoquinone). TeNPs generation kinetics were monitored to define the optimal conditions to produce TeNPs as a function of various carbon sources and lawsone concentration...
February 15, 2017: Journal of Hazardous Materials
Kai Kudoh, Genma Kubota, Rintaro Fujii, Yusuke Kawano, Masaki Ihara
1-Deoxy-d-xylulose 5-phosphate synthase (DXS) is a rate-limiting enzyme in the 2-C-methyl-d-erythritol 4-phosphate (MEP) pathway, which is responsible for production of two precursors of all isoprenoids, isopentenyl diphosphate and dimethylallyl diphosphate (DMAPP). Previously, we attempted the overexpression of endogenous DXS in Synechocystis sp. PCC6803, and revealed that although the mRNA level was 4-fold higher, the DXS protein level was only 1.5-fold higher compared with those of the original strain, suggesting the lability of endogenous DXS protein...
November 14, 2016: Journal of Bioscience and Bioengineering
Dariusz M Niedzwiedzki, Preston L Dilbeck, Qun Tang, Elizabeth C Martin, David F Bocian, C Neil Hunter, Dewey Holten
Light-harvesting complex 2 (LH2) from the semi-aerobically grown purple phototrophic bacterium Rhodobacter sphaeroides was studied using optical (static and time-resolved) and resonance Raman spectroscopies. This antenna complex comprises bacteriochlorophyll (BChl) a and the carotenoid spheroidenone, a ketolated derivative of spheroidene. The results indicate that the spheroidenone-LH2 complex contains two spectral forms of the carotenoid: (1) a minor, "blue" form with an S2 (1(1)B u(+) ) spectral origin band at 522 nm, shifted from the position in organic media simply by the high polarizability of the binding site, and (2) the major, "red" form with the origin band at 562 nm that is associated with a pool of pigments that more strongly interact with protein residues, most likely via hydrogen bonding...
November 16, 2016: Photosynthesis Research
Julia Hahn, Sebastian Thalmann, Anzhela Migur, Raphael Freiherr von Boeselager, Nina Kubatova, Elena Kubareva, Harald Schwalbe, Elena Evguenieva-Hackenberg
Up to now, very small protein-coding genes have remained unrecognized in sequenced genomes. We identified an mRNA of 165 nucleotides (nt), which is conserved in Bradyrhizobiaceae and encodes a polypeptide with 14 amino acid residues (aa). The small mRNA harboring a unique Shine-Dalgarno sequence (SD) with a length of 17 nt was localized predominantly in the ribosome-containing P100 fraction of Bradyrhizobium japonicum USDA 110. Strong interaction between the mRNA and 30S ribosomal subunits was demonstrated by their co-sedimentation in sucrose density gradient...
November 11, 2016: RNA Biology
Folmer Fredslund, Harm Otten, Sabrina Gemperlein, Jens Christian N Poulsen, Yvonne Carius, Gert Wieland Kohring, Leila Lo Leggio
Bradyrhizobium japonicum sorbitol dehydrogenase is NADH-dependent and is active at elevated temperatures. The best substrate is D-glucitol (a synonym for D-sorbitol), although L-glucitol is also accepted, giving it particular potential in industrial applications. Crystallization led to a hexagonal crystal form, with crystals diffracting to 2.9 Å resolution. In attempts to phase the data, a molecular-replacement solution based upon PDB entry 4nbu (33% identical in sequence to the target) was found. The solution contained one molecule in the asymmetric unit, but a tetramer similar to that found in other short-chain dehydrogenases, including the search model, could be reconstructed by applying crystallographic symmetry operations...
November 1, 2016: Acta Crystallographica. Section F, Structural Biology Communications
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