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biosynthesis of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and characterisation of its blend with oil palm empty fruit bunch fibers.poly(3-hydroxybutyrate-co-38 mol%-3-hydroxyvalerate) [p(3hb-co-38mol%-3hv)] was produced by cupriavidus sp. usmaa2-4 in the presence of oleic acid and 1-pentanol. due to enormous production of empty fruit bunch (efb) in the oil palm plantation and high production cost of p(3hb-co-3hv), oil palm efb fibers were used for biocomposites preparation. in this study, maleic anhydride (ma) and benzoyl peroxide (dbpo) were used to improve the miscibility between p(3hb-co-3hv) and efb fibers. introduction ...201021115240
bacterial gold sensing and resistance.gold ions are mobilized and disseminated through the environment and enter into the cells by non-specific intake. to avoid deleterious effect that occurs even at very low concentrations, bacteria such as salmonella enterica and cupriavidus metallidurans use au-specific merr-type transcriptional regulators to detect the presence of these toxic ions, and control the expression of specific resistance factors. in contrast to the related copper sensor cuer, the au-selective metalloregulatory proteins ...201021153861
extension of the substrate utilization range of ralstonia eutropha strain h16 by metabolic engineering to include mannose and glucose.the gram-negative facultative chemolithoautotrophic bacterium ralstonia eutropha strain h16 is known for its narrow carbohydrate utilization range, which limits its use for biotechnological production of polyhydroxyalkanoates and possibly other products from renewable resources. to broaden its substrate utilization range, which is for carbohydrates and related compounds limited to fructose, n-acetylglucosamine, and gluconate, strain h16 was engineered to use mannose and glucose as sole carbon so ...201021169447
improved polyhydroxybutyrate (phb) production in transgenic tobacco by enhancing translation efficiency of bacterial phb biosynthetic genes.polyhydroxybutyrate [p(3hb)] was produced in the transgenic tobacco harboring the genes encoding acetoacetyl-coa reductase (phab) and polyhydroxyalkanoate synthase (phac) from ralstonia eutropha (cupriavidus necator) with optimized codon usage for expression in tobacco. p(3hb) contents in the transformants (0.2mg/g dry cell weight in average) harboring the codon-optimized phab gene was twofold higher than the control transformants harboring the wild-type phab gene. the immunodetection revealed a ...201021185778
insertion sequence elements in cupriavidus metallidurans ch34: distribution and role in adaptation.cupriavidus metallidurans ch34 is a β-proteobacterium well equipped to cope with harsh environmental conditions such as heavy metal pollution. the strain carries two megaplasmids specialized in the response to heavy metals and a considerable number of genomic islands, transposons and insertion sequence (is) elements. the latter were characterized in detail in this study, which revealed nine new is elements totaling to 21 distinct is elements from 10 different is families and reaching a total of ...201021185859
development and characterization of an enzymatic method for the rapid determination of gamma hydroxybutyric acid.gamma hydroxybutyric acid (ghb) is a regulated therapeutic drug, which naturally occurs in mammalian brain tissues as an intermediate of the gaba (gamma aminobutyric acid) neurotransmitter metabolism. the increasing misuse of ghb as a narcotic or abusing drug in recent years calls for the development of a simple and rapid screening method as an alternative to the currently available, technically demanding diagnostic methods. we have developed a rapid enzymatic assay based on the ghb dehydrogenas ...201021197843
sulfoacetate is degraded via a novel pathway involving sulfoacetyl-coa and sulfoacetaldehyde in cupriavidus necator h16.bacterial degradation of sulfoacetate, a widespread natural product, proceeds via sulfoacetaldehyde and requires a considerable initial energy input. whereas the fate of sulfoacetaldehyde in cupriavidus necator (ralstonia eutropha) h16 is known, the pathway from sulfoacetate to sulfoacetaldehyde is not. the genome sequence of the organism enabled us to hypothesize that the inducible pathway, which initiates sau (sulfoacetate utilization), involved a four-gene cluster (saurstu; h16_a2746 to h16_a ...201020693281
production of p(3-hydroxybutyrate-co-3-hydroxyhexanoate-co-3-hydroxyoctanoate) terpolymers using a chimeric pha synthase in recombinant ralstonia eutropha and pseudomonas putida.recombinant strains of ralstonia eutropha and pseudomonas putida harboring a chimeric polyhydroxyalkanoate (pha) synthase, which consisted of pha synthases of aeromonas caviae and r. eutropha, produced 3-hydroxybutyrate (3hb)-based pha copolymers comprised of 3-hydroxyhexanoate and 3-hydroxyoctanoate units from dodecanoate (87-97 mol % 3hb), indicating that the chimeric pha synthase possesses desirable substrate specificity leading to the production of 3hb-rich copolymers.201020699558
elucidation of beta-oxidation pathways in ralstonia eutropha h16 by examination of global gene expression.ralstonia eutropha h16 is capable of growth and polyhydroxyalkanoate production on plant oils and fatty acids. however, little is known about the triacylglycerol and fatty acid degradation pathways of this bacterium. we compare whole-cell gene expression levels of r. eutropha h16 during growth and polyhydroxyalkanoate production on trioleate and fructose. trioleate is a triacylglycerol that serves as a model for plant oils. among the genes of note, two potential fatty acid β-oxidation operons an ...201020709892
microarray analysis of a microbe-mineral interaction.the weathering of volcanic minerals makes a significant contribution to the global silicate weathering budget, influencing carbon dioxide drawdown and long-term climate control. basalt rocks may account for over 30% of the global carbon dioxide drawdown in silicate weathering. micro-organisms are known to play a role in rock weathering yet the genomics and genetics of biological rock weathering are unknown. we apply dna microarray technology to determine putative genes involved in weathering usi ...201020718869
roles of multiple acetoacetyl coenzyme a reductases in polyhydroxybutyrate biosynthesis in ralstonia eutropha h16.the bacterium ralstonia eutropha h16 synthesizes polyhydroxybutyrate (phb) from acetyl coenzyme a (acetyl-coa) through reactions catalyzed by a β-ketothiolase (phaa), an acetoacetyl-coa reductase (phab), and a polyhydroxyalkanoate synthase (phac). an operon of three genes encoding these enzymatic steps was discovered in r. eutropha and has been well studied. sequencing and analysis of the r. eutropha genome revealed putative isologs for each of the phb biosynthetic genes, many of which had never ...201020729355
biorefining of precious metals from wastes: an answer to manufacturing of cheap nanocatalysts for fuel cells and power generation via an integrated biorefinery?bio-manufacturing of nano-scale palladium was achieved via enzymatically-mediated deposition of pd from solution using desulfovibrio desulfuricans, escherichia coli and cupriavidus metallidurans. dried 'bio-pd' materials were sintered, applied onto carbon papers and tested as anodes in a proton exchange membrane (pem) fuel cell for power production. at a pd(0) loading of 25% by mass the fuel cell power using bio-pd( d. desulfuricans ) (positive control) and bio-pd( e. coli ) (negative control) w ...201020734111
effects of electrochemical reduction reactions on the biodegradation of recalcitrant organic compounds (rocs) and bacterial community diversity.five bacterial species, capable of degrading the recalcitrant organic compounds (rocs) diethyleneglycol monomethylether (dgmme), 1-amino-2-propanol (apol), 1-methyl-2- pyrrolidinone (nmp), diethyleneglycol monoethylether (dgmee), tetraethyleneglycol (teg), and tetrahydrothiophene 1,1-dioxide (sulfolane), were isolated from an enrichment culture. cupriavidus sp. catabolized 93.5+/-1.7 mg/l of teg, 99.3+/-1.2 mg/l of dgmme, 96.1+/-1.6mg/l of apol, and 99.5+/-0.5mg/l of nmp in 3 days. acineobacter ...201020798588
nosocomial transmission of cupriavidus pauculus during extracorporeal membrane oxygenation.patients undergoing extracorporeal membrane oxygenation (ecmo) are at increased risk of infection. we present the first known report of nosocomial infection with cupriavidus pauculus attributable to contamination from ecmo equipment and describe the measures taken to halt subsequent infections. a cluster of infections in ecmo patients should prompt team members to consider contamination of equipment with environmental pathogens as a possible cause.201020811172
production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by cupriavidus necator from waste rapeseed oil using propanol as a precursor of 3-hydroxyvalerate.waste rapeseed oil is a useful substrate for polyhydroxyalkanoates (pha) production employing cupriavidus necator h16. in fed-batch mode, we obtained biomass and pha yields of 138 and 105 g l(-1), respectively. yield coefficient and volumetric productivity were 0.83 g pha per g oil and 1.46 g l(-1) h(-1), respectively. propanol at 1% (v/v) enhanced both pha and biomass formation significantly and, furthermore, resulted in incorporation of 3-hydroxyvalerate units into pha structure. thus, propano ...201020814716
dihydrolipoamide dehydrogenases of advenella mimigardefordensis and ralstonia eutropha catalyze cleavage of 3,3'-dithiodipropionic acid into 3-mercaptopropionic acid.the catabolism of the disulfide 3,3'-dithiodipropionic acid (dtdp) is initiated by the reduction of its disulfide bond. three independent tn5::mob-induced mutants of advenella mimigardefordensis strain dpn7(t) were isolated that had lost the ability to utilize dtdp as the sole source of carbon and energy and that harbored the transposon insertions in three different sites of the same dihydrolipoamide dehydrogenase gene encoding the e3 subunit of the pyruvate dehydrogenase multi-enzyme complex of ...201020833784
probing the active site of an o2-tolerant nad+-reducing [nife]-hydrogenase from ralstonia eutropha h16 by in situ epr and ftir spectroscopy. 201020857465
effect of feeding regimens on polyhydroxybutyrate production from food wastes by cupriavidus necator.we investigated the effects of different feeding regimens (1-pulse, stepwise, and continuous) of fermented food-waste liquid on polyhydroxybutyrate (phb) production. the fermentation liquid was filtered with a membrane filter (pore size, 0.45 μm) to remove anaerobic microorganisms and solids and used as a carbon source for cupriavidus necator. one-pulse feeding yielded the highest cell concentration of c. necator. however, the phb concentration was higher in the stepwise- and continuous-feeding ...201020870404
characterization of acrylamidase isolated from a newly isolated acrylamide-utilizing bacterium, ralstonia eutropha aum-01.a mesophilic bacterium capable of utilizing acrylamide was isolated, aum-01, from soil collected from leaf litter at picnic point on the uw-madison campus. in minimal medium with acrylamide as the sole carbon and nitrogen source, a batch culture of aum-01 completely converted 28.0 mm acrylamide to acrylic acid in 8 h and reached a cell density of 0.3 (a₆₀₀)). afterward all the acrylic acid was degraded by 20 h with the cell density increasing to 1.9 (a₆₀₀). the acrylamide-utilizing bacterium was ...201020872004
gas pressure effects on the rates of catalytic h(2) oxidation by hydrogenases.during catalysis by hydrogenases, entities no larger than h(2) or h(+) reach and leave a deeply buried active site, by as yet unidentified pathways. novel experiments, conducted mainly with the membrane-bound [nife]-hydrogenase from ralstonia eutropha, explore why small excess gas pressures (h(2) or he) attenuate the rate of h(2) oxidation.201020922264
investigations on the microbial catabolism of the organic sulfur compounds tdp and dtdp in ralstonia eutropha h16 employing dna microarrays.in this study, we have investigated the transcriptome of ralstonia eutropha h16 during cultivation with gluconate in presence of 3,3'-thiodipropionic acid (tdp) or 3,3'-dithiodipropionic acid (dtdp) during biosynthesis of poly(3-hydroxybutyrate-co-3-mercaptopropionate). genome-wide transcriptome analyses revealed several genes which were upregulated during cultivation in presence of the above-mentioned compounds. obtained data strongly suggest that two abc-type transport system and three probabl ...201020924576
production of polyhydroxyalkanoates (phas) with canola oil as carbon source.wautersia eutropha was able to synthesize medium chain length polyhydroxyalkanoates (phas) when canola oil was used as carbon source. w. eutropha was cultivated using fructose and ammonium sulphate as carbon and nitrogen sources, respectively, for growth and inoculum development. the experiments were done in a laboratory scale bioreactor in three stages. initially, the biomass was adapted in a batch culture. secondly, a fed-batch was used to increase the cell dry weight and pha concentration to ...201020933541
biosynthesis of polyhydroxyalkanoate homopolymers by pseudomonas putida.pseudomonas putida kt2442 has been a well-studied producer of medium-chain-length (mcl) polyhydroxyalkanoate (pha) copolymers containing c6 ~ c14 monomer units. a mutant was constructed from p. putida kt2442 by deleting its phag gene encoding r-3-hydroxyacyl-acp-coa transacylase and several other β-oxidation related genes including fadb, fada, fadb2x, and fadax. this mutant termed p. putida kthh03 synthesized mcl homopolymers including poly(3-hydroxyhexanoate) (phhx) and poly(3-hydroxyheptanoate ...201021046374
robust crop resistance to broadleaf and grass herbicides provided by aryloxyalkanoate dioxygenase transgenes.engineered glyphosate resistance is the most widely adopted genetically modified trait in agriculture, gaining widespread acceptance by providing a simple robust weed control system. however, extensive and sustained use of glyphosate as a sole weed control mechanism has led to field selection for glyphosate-resistant weeds and has induced significant population shifts to weeds with inherent tolerance to glyphosate. additional weed control mechanisms that can complement glyphosate-resistant crops ...201021059954
exploring kinetics of phenol biodegradation by cupriavidus taiwanesis 187.phenol biodegradation in batch systems using cupriavidus taiwanesis 187 has been experimentally studied. to determine the various parameters of a kinetic model, combinations of rearranged equations have been evaluated using inverse polynomial techniques for parameter estimation. the correlations between lag phase and phase concentration suggest that considering phenol inhibition in kinetic analysis is helpful for characterizing phenol degradation. this study proposes a novel method to determine ...201021614192
enzyme reactivation by hydrogen peroxide in heme-based tryptophan dioxygenase.an intriguing mystery about tryptophan 2,3-dioxygenase (tdo) is its hydrogen peroxide-triggered enzyme reactivation from the resting ferric oxidation state to the catalytically active ferrous form. in this work, we find that such an odd fe(iii) reduction by an oxidant depends on the presence of l-trp, which ultimately serves as the reductant for the enzyme. in the peroxide reaction with tdo, a previously unknown catalase-like activity is detected. a ferryl species (δ = 0.055 mm/s and δe(q) = 1.7 ...201121632548
chemo-enzymatic synthesis of polyhydroxyalkanoate (pha) incorporating 2-hydroxybutyrate by wild-type class i pha synthase from ralstonia eutropha.a previously established improved two-phase reaction system has been applied to analyze the substrate specificities and polymerization activities of polyhydroxyalkanoate (pha) synthases. we first analyzed the substrate specificity of propionate coenzyme a (coa) transferase and found that 2-hydroxybutyrate (2hb) was converted into its coa derivative. then, the synthesis of pha incorporating 2hb was achieved by a wild-type class i pha synthase from ralstonia eutropha. the pha synthase stereoselect ...201121667085
monitoring the in situ crystallization of native biopolyester granules in ralstonia eutropha via infrared spectroscopy.poly(3-hydroxybutyrate) (phb), a representative polyhydroxyalkanoate (pha), is a naturally occurring biopolyester stored as tiny, intracellular granules in microbial cells. in vivo, native phb granules are amorphous, stabilized by a monolayer membrane and intra-granule water. when subjected to varying environmental conditions, the native granules may become partially crystalline. the in situ crystallinity of native phb granules in ralstonia eutropha cells suspended in aqueous solution was monito ...201121801758
role of the hoxz subunit in the electron transfer pathway of the membrane-bound [nife]-hydrogenase from ralstonia eutropha immobilized on electrodes.the role of the diheme cytochrome b (hoxz) subunit in the electron transfer pathway of the membrane-bound [nife]-hydrogenase (mbh) hetero-trimer from ralstonia eutropha h16 has been investigated. the mbh in its native hetero-trimeric state was immobilized on electrodes and subjected to spectroscopic and electrochemical analysis. surface enhanced resonance raman spectroscopy was used to monitor the redox and coordination state of the hoxz heme cofactors while concomitant protein film voltammetric ...201121761881
molecular genetics and biochemistry of n-acetyltaurine degradation by cupriavidus necator h16.cupriavidus necator h16 (dsm 428), whose genome has been sequenced, was found to degrade n-acetyltaurine as a sole source of carbon and energy for growth. utilization of the compound was quantitative. the degradative pathway involved an inducible n-acetyltaurine amidohydrolase (naas), which catalyzed the cleavage of n-acetyltaurine to acetate and taurine. the degradation of the latter compound is via an inducible, degradative pathway that involves taurine dehydrogenase [ec 1.4.2.-], sulfoacetald ...201121757489
a non-nadb type l-aspartate dehydrogenase from ralstonia eutropha strain jmp134: molecular characterization and physiological functions.we report the molecular characterization and physiological function of a novel l-aspartate dehydrogenase (aspdh). the purified enzyme was a 28-kda dimeric protein, exhibiting high catalytic activity for l-aspartate (l-asp) oxidation using nad and/or nadp as cofactors. quantitative real-time pcr analysis indicated that the genes involved in the aspdh gene cluster, poly-3-hydroxyalkanoate (pha) biosynthesis, and the tca cycle were substantially induced by l-asp in wild-type cells. in contrast, exp ...201121821928
complete genome sequence of the type strain cupriavidus necator n-1.here we announce the complete genome sequence of the copper-resistant bacterium cupriavidus necator n-1, the type strain of the genus cupriavidus. the genome consists of two chromosomes and two circular plasmids. based on genome comparison, the chromosomes of c. necator n-1 share a high degree of similarity with the two chromosomal replicons of the bioplastic-producing hydrogen bacterium ralstonia eutropha h16. the two strains differ in their plasmids and the presence of hydrogenase genes, which ...201121742890
genome-scale reconstruction and in silico analysis of the ralstonia eutropha h16 for polyhydroxyalkanoate synthesis, lithoautotrophic growth, and 2-methyl citric acid production.abstract:201121711532
biosynthesis of novel polyhydroxyalkanoate containing 3-hydroxy-4-methylvalerate by chromobacterium sp. usm2.aims:ôçé polyhydroxyalkanoate (pha) with enhanced physicochemical properties will be ideal for a wide range of practical applications. the incorporation of 3-hydroxy-4-methylvalerate (3h4mv) into the polymer backbone is known to improve the overall properties of the resulting polymer. however, the most suitable micro-organism and pha synthase that can synthesize this monomer efficiently still remain unknown at present. therefore, we evaluated the abilities of a locally isolated chromobacterium s ...201121689225
legume-nodulating betaproteobacteria: diversity, host range and future prospects.rhizobia form specialized nodules on the roots of legumes (fabaceae) and fix nitrogen in exchange for carbon from the host plant. although the majority of legumes form symbioses with rhizobium and its relatives in the alphaproteobacteria, some legumes, such as those in the large genus mimosa, are nodulated predominantly by betaproteobacteria in the genera burkholderia and cupriavidus. the principal centers of diversity of these bacteria are in central brazil and south africa. molecular phylogene ...201121830951
contributions of five secondary metal uptake systems to metal homeostasis of cupriavidus metallidurans ch34.cupriavidus metallidurans is adapted to high concentrations of transition metal cations and is a model system for studying metal homeostasis in difficult environments. the elemental composition of c. metallidurans cells cultivated under various conditions was determined, revealing the ability of the bacterium to shield homeostasis of one essential metal from the toxic action of another. the contribution of metal uptake systems to this ability was studied. c. metallidurans contains three cora mem ...201121742896
microbially supported synthesis of catalytically active bimetallic pd-au nanoparticles.bimetallic nanoparticles are considered the next generation of nanocatalysts with increased stability and catalytic activity. bio-supported synthesis of monometallic nanoparticles has been proposed as an environmentally friendly alternative to the conventional chemical and physical protocols. in this study we synthesize bimetallic bio-supported pd-au nanoparticles for the first time using microorganisms as support material. the synthesis involved two steps: (1) formation of monometallic bio-supp ...201121830201
specific pcr to identify the heavy-metal-resistant bacterium cupriavidus metallidurans.the aim of this study is to develop a polymerase chain reaction (pcr) assay for rapid detection of cupriavidus metallidurans. pcr primers targeting the signal transduction histidine kinase gene were designed and designated cm-f1/cm-r1. strains of c.-ámetallidurans were positively identified. the size of the pcr products was 437-ábp, as expected. this pcr method enables monitoring of industrial, environmental and clinical sources for presence of c.-ámetallidurans.201121720772
the initial metabolic conversion of levulinic acid in cupriavidus necator.levulinic acid or 4-ketovaleric acid is a potential renewable substrate for production of polyhydroxyalkanoates. in this work, the initial reactions of la metabolism by cupriavidus necator were examined in vitro. the organic acid was converted by membrane-bound crude enzymes obtained from the cells pre-grown on la, while no la activity was detected from cells pre-grown on acetic acid. acetyl-coa and propionyl-coa were two major intermediates in the initial reactions of la conversion. a mass bala ...201121821073
insights into the structure of the active site of the o(2)-tolerant membrane bound [nife] hydrogenase of r. eutropha h16 by molecular modelling.structural models for the ni-b state of the wild-type and c81s protein variant of the membrane-bound [nife] hydrogenase from ralstonia eutropha h16 were derived by applying the homology model technique combined with molecular simulations and a hybrid quantum mechanical/molecular mechanical approach. the active site structure was assessed by comparing calculated and experimental ir spectra, confirming the view that the active site structure is very similar to those of anaerobic standard hydrogena ...201121833416
heavy metal resistance in cupriavidus metallidurans ch34 is governed by an intricate transcriptional network.the soil bacterium cupriavidus metallidurans ch34 contains a high number of heavy metal resistance genes making it an interesting model organism to study microbial responses to heavy metals. in this study the transcriptional response of strain ch34 was measured when challenged to sub-lethal concentrations of various essential or toxic metals. based on the global transcriptional responses for each challenge and the overlap in upregulated genes between different metal responses, the sixteen metals ...201121706166
polyhydroxyalkanoate (pha) synthesis by class iv pha synthases employing ralstonia eutropha phb(-)4 as host strain.class iv polyhydroxyalkanoate (pha) synthase from bacillus cereus yb-4 (pharc(yb4)) or b. megaterium nbrc15308(t) (pharc(bm)) was expressed in ralstonia eutropha phb(-)4 to compare the ability to produce pha and the substrate specificity of pharcs. pharc(yb4) produced significant amounts of pha and had broader substrate specificity than pharc(bm).201121821924
evaluation and optimisation of bacterial genomic dna extraction for no-culture techniques applied to vinegars.direct genomic dna extraction from vinegars was set up and suitability for pcr assays performed by pcr/dgge and sequencing of 16s rrna gene. the method was tested on 12 intermediary products of special vinegars, fruit vinegars and condiments produced from different raw materials and procedures. dnas extraction was performed on pellets by chemical, enzymatic, resin mediated methods and their modifications. suitable yield and dna purity were obtained by modification of a method based on the use of ...201121839388
the effect of carbon source supplementation on the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by cupriavidus necator.the objective of the present study was to investigate the ability of cupriavidus necator to produce poly-(3-hydroxybutyrate-co-3-hydroxyvalerate) on various carbon sources in batch cultivation. these results show that c. necator produces poly-3-hydroxybutyrate from single carbon sources. the highest poly-3-hydroxybutyrate (p3hb) content was achieved at growth on fructose in the exponential growth phase. the maximum yield of the p3hv content was obtained when fructose was mixed with acetate. the ...201121679245
use of an isothermal microcalorimetry assay to characterize microbial oxalotrophic activity.isothermal microcalorimetry (imc) has been used in the past to monitor metabolic activities in living systems. a few studies have used it on ecological research. in this study, imc was used to monitor oxalotrophic activity, a widespread bacterial metabolism found in the environment, and particularly in soils. six model strains were inoculated in solid angle media with k-oxalate as the sole carbon source. cupriavidus oxalaticus, cupriavidus necator, and streptomyces violaceoruber presented the hi ...201121696406
interaction between poly(3-hydroxybutyrate) granule-associated proteins as revealed by two-hybrid analysis and identification of a new phasin in ralstonia eutropha.a large number of polypeptides are attached to phb granules of ralstonia eutropha such as phb synthase (phac1), several phb depolymerases (phazs) and phasins (phaps), regulator protein pharreu and possibly others. in this study we used the bacterial adenylate cyclase-based two hybrid assay to investigate interactions between known phb granule associated proteins (pgaps) and to screen for new pgaps. the utility of the system was tested by in vivo verification of previously postulated interaction ...201121737497
The crystal structure of an oxygen-tolerant hydrogenase uncovers a novel iron-sulphur centre.Hydrogenases are abundant enzymes that catalyse the reversible interconversion of H(2) into protons and electrons at high rates. Those hydrogenases maintaining their activity in the presence of O(2) are considered to be central to H(2)-based technologies, such as enzymatic fuel cells and for light-driven H(2) production. Despite comprehensive genetic, biochemical, electrochemical and spectroscopic investigations, the molecular background allowing a structural interpretation of how the catalytic ...201122002606
Effects of Different Substrate Composition on Biosynthesis of Polyhydroxybutyrate-co-hydroxyvalerate by Recombinant Escherichia coli.Cupriavidus necator is well known for its ability to accumulate polyhydroxybutyrate (PHB). When supplemented with propionic acid (or sodium propionate) in the growth medium, the bacterium is also able to synthesize polyhydroxybutyrate-co-hydroxyvalerate (PHBV). In order to increase the fraction of 3-hydroxyvalerate (3HV) in PHBV, we cloned the propionate permease gene prpP from C. necator and the propionyl-CoA synthase gene prpE from Cupriavidus taiwanensis and transformed into an Escherichia co ...201122203393
effect of glucose on the fatty acid composition of cupriavidus necator jmp134 during 2,4-dichlorophenoxyacetic acid degradation: implications for lipid-based stable isotope probing methods.combining lipid biomarker profiling with stable isotope probing (sip) is a powerful technique for studying specific microbial populations responsible for the degradation of organic pollutants in various natural environments. however, the presence of other easily degradable substrates may induce significant physiological changes by altering both the rate of incorporation of the target compound into the biomass and the microbial lipid profiles. in order to test this hypothesis, cupriavidus necator ...201121856833
genetic diversity of mimosa pudica rhizobial symbionts in soils of french guiana: investigating the origin and diversity of burkholderia phymatum and other beta-rhizobia.the genetic diversity of 221 mimosa pudica bacterial symbionts trapped from eight soils from diverse environments in french guiana was assessed by 16s rrna pcr-rflp, rep-pcr fingerprints, as well as by phylogenies of their 16s rrna and reca housekeeping genes, and by their nifh, noda and nodc symbiotic genes. interestingly, we found a large diversity of beta-rhizobia, with burkholderia phymatum and burkholderia tuberum being the most frequent and diverse symbiotic species. other species were als ...201122093060
Isolation of Cupriavidus metallidurans from razor blade during paraffin embedded tissue sectioning. 201121888031
Enhancing the 3-hydroxyvalerate component in bioplastic PHBV production by Cupriavidus necator.In the current context of global warming, the substitution of conventional plastics with bioplastics is a challenge. To take up this challenge, we must meet different technical and economic constraints. In the case of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), the technical properties can be modulated by varying the 3-hydroxyvalerate content. 3-Hydroxyvalerate (3-HV) enhancement is an issue; therefore, simultaneous evaluation of several 3-hydroxyvalerate-enhancing substrates through fr ...201121905226
Cupriavidus and Burkholderia species associated with agricultural plants that grow in alkaline soils.The presence of Burkholderia, Cupriavidus, and Ralstonia species in northeastern Mexico was investigated. An analysis of the root surrounding soil from different agricultural plants led to the isolation of Burkholderia and Cupriavidus species but no Ralstonia strains. Most Cupriavidus species were unknown and grouped into two clusters according to ARDRA profiles. The 16S rRNA sequence analysis showed that the Cupriavidus isolates were highly related among them and with different Cupriavidus spec ...201122203548
Molecular basis of the cooperative binding of Cu(I) and Cu(II) to the CopK protein from Cupriavidus metallidurans CH34.The bacterium Cupriavidus metallidurans CH34 is resistant to high environmental concentrations of many metal ions. Upon copper challenge, it upregulates the periplasmic protein CopK (8.3 kDa). The function of CopK in the copper resistance response is ill-defined, but CopK demonstrates an intriguing cooperativity: occupation of a high-affinity Cu(I) binding site generates a high-affinity Cu(II) binding site, and the high-affinity Cu(II) binding enhances Cu(I) binding. Native CopK and targeted var ...201121936507
identification of mutation points in cupriavidus necator ncimb 11599 and genetic reconstitution of glucose-utilization ability in wild strain h16 for polyhydroxyalkanoate production.although the facultative chemolithoautotrophic cupriavidus necator (formerly ralstonia eutropha) wild strain h16 is potentially useful as a host for metabolic engineering aimed at polyhydroxyalkanoate production, this organism is deficient in assimilating glucose, a major sugar in non-edible cellulosic resources. growth properties of c. necator h16 harboring heterologous glf (encoding glucose-facilitated diffusion transporter) and glk (encoding glucokinase) from zymomonas mobilis strongly sugges ...201122014784
2,4,5-trichlorophenol degradation using a novel tio2-coated biofilm carrier: roles of adsorption, photocatalysis, and biodegradation.intimate coupling of photocatalysis and biodegradation (icpb) offers potential for degrading biorecalcitrant and toxic organic compounds. this study reports on a novel sponge-type, tio(2)-coated biofilm carrier that showed significant adherence of tio(2) and ability to accumulate biomass in its interior. this carrier was tested for icpb in a continuous-flow photocatalytic circulating-bed biofilm reactor (pcbbr) to mineralize 2,4,5-trichlorophenol (tcp), which is biorecalcitrant. four mechanisms ...201121861477
from single cells to microbial population dynamics: modelling in biotechnology based on measurements of individual cells.the development of dynamic modelling of microbial populations in bioprocesses is reviewed. in the 1960s arnold fredrickson established the theoretical basis of such models, and other researchers have subsequently advanced them. this review explores the relationships that describe cell proliferation and evaluates the importance of the application of flow cytometry to the fundamental parameterisation of the models for their use in bioprocess engineering. the section "individual-based modelling" di ...201121072703
improved detergent-based recovery of polyhydroxyalkanoates (phas).extracting polyhydroxyalkanoate (pha) polymer from bacterial cells often involves harsh conditions, including use of environmentally harmful solvents. we evaluated different detergents under various conditions to extract pha from ralstonia eutropha and escherichia coli cells. most detergents tested recovered highly pure pha polymer from cells in amounts that depended on the percentage of polymer present in the cell. detergents such as linear alkylbenzene sulfonic acid (las-99) produced a high yi ...201121207109
structure of ralstonia eutropha flavohemoglobin in complex with three antibiotic azole compounds.flavohemoglobins (flavohbs) are enzymes that operate primarily as nitric oxide dioxygenases and shuttle thereby electrons among nad(p)h, fad, heme, and a ligated redox-active substrate such as o(2). they function in the bacterial defense against nitrosative stress and are therefore considered as targets for new antibiotic drugs. recently, azole derivatives were proven to be attractive nitric oxide dioxygenase inhibitors, and to explore their binding characteristics, we determined the x-ray struc ...201121210640
cupriavidus taiwanensis bacteroids in mimosa pudica indeterminate nodules are not terminally differentiated.the beta-rhizobium cupriavidus taiwanensis forms indeterminate nodules on mimosa pudica. c. taiwanensis bacteroids resemble free-living bacteria in terms of genomic dna content, cell size, membrane permeability, and viability, in contrast to bacteroids in indeterminate nodules of the galegoid clade. bacteroid differentiation is thus unrelated to nodule ontogeny.201121257807
recovery and purification of intracellular polyhydroxyalkanoates from recombinant cupriavidus necator using water and ethanol.a new halogen-free and environmental-friendly method using water and ethanol is developed as an alternative for the recovery of polyhydroxyalkanoates (pha) from recombinant cupriavidus necator in comparison to the established chloroform extraction method. after optimisation, our results showed that the halogen-free method produced a pha with 81% purity and 96% recovery yield, in comparison to the chloroform extraction system which resulted in a highly pure pha with 95% yield. although the purity ...201122038551
spectroscopic characterization of the metal-binding sites in the periplasmic metal-sensor domain of cnrx from cupriavidus metallidurans ch34.cnrx, the dimeric metal sensor of the three-protein transmembrane signal transduction complex cnryxh of cupriavidus metallidurans ch34, contains one metal-binding site per monomer. both ni and co elicit a biological response and bind the protein in a 3n2o1s coordination sphere with a nearly identical octahedral geometry as shown by the x-ray structure of cnrxs, the soluble domain of cnrx. however, in solution cnrxs is titrated by 4 co-equiv and exhibits an unexpected intense band at 384 nm that ...201121942751
biosynthesis and characterization of polyhydroxyalkanoate block copolymer p3hb-b-p4hb.polyhydroxyalkanoates (pha) synthesis genes phbc and orfz cloned from ralstonia eutropha h16 were transformed into beta-oxidation weakened pseudomonas putida ktoy08δgc, a mutant of p. putida kt2442. the recombinant p. putida strain termed kthh06 was able to produce a short-chain-length pha block copolymer consisting of poly(3-hydroxybutyrate) (p3hb) as one block and poly(4-hydroxybutyrate) (p4hb) as another block. one-dimensional and two-dimensional nuclear magnetic resonance (nmr) clearly indic ...201121863836
production of polyhydroxyalkanoates from waste frying oil by cupriavidus necator.abstract: polyhydroxyalkanoates (phas) are biopolymers, which can replace petrochemical plastics in many applications. however, these bioplastics are currently far more expensive than petrochemical plastics. many researchers are investigating the use of inexpensive substrates derived from waste streams. waste frying oil is abundant and can be used in pha production without filtration.cupriavidus necator (formerly known as ralstonia eutropha) is a versatile organism for the production of phas. sm ...201121906352
sulfoquinovose degraded by pure cultures of bacteria with release of c(3) -organosulfonates: complete degradation in two-member communities.sulfoquinovose (sq, 6-deoxy-6-sulfoglucose) was synthesized chemically. an hplc-elsd method to separate sq and other chromophore-free sulfonates, e.g. 2,3-dihydroxypropane-1-sulfonate (dhps), was developed. a set of 10 genome-sequenced, sulfonate-utilizing bacteria did not utilize sq, but an isolate, pseudomonas putida sq1, from an enrichment culture did so. the molar growth yield with sq was half of that with glucose, and 1 mol 3-sulfolactate (mol sq)(-1) was formed during growth. the 3-sulfol ...201122150877
Microalgae as bioreactors for bioplastic production.Poly-3-hydroxybutyrate (PHB) is a polyester with thermoplastic properties that is naturally occurring and produced by such bacteria as Ralstonia eutropha H16 and Bacillus megaterium. In contrast to currently utilized plastics and most synthetic polymers, PHB is biodegradable, and its production is not dependent on fossil resources making this bioplastic interesting for various industrial applications.201122004563
Microbial degradation of furanic compounds: biochemistry, genetics, and impact.Microbial metabolism of furanic compounds, especially furfural and 5-hydroxymethylfurfural (HMF), is rapidly gaining interest in the scientific community. This interest can largely be attributed to the occurrence of toxic furanic aldehydes in lignocellulosic hydrolysates. However, these compounds are also widespread in nature and in human processed foods, and are produced in industry. Although several microorganisms are known to degrade furanic compounds, the variety of species is limited mostly ...201122031465
Aromatic compounds degradation plays a role in colonization of Arabidopsis thaliana and Acacia caven by Cupriavidus pinatubonensis JMP134.Plant rhizosphere and internal tissues may constitute a relevant habitat for soil bacteria displaying high catabolic versatility towards xenobiotic aromatic compounds. Root exudates contain various molecules that are structurally related to aromatic xenobiotics and have been shown to stimulate bacterial degradation of aromatic pollutants in the rhizosphere. The ability to degrade specific aromatic components of root exudates could thus provide versatile catabolic bacteria with an advantage for r ...201122186997
Aerobic pretreatment of olive oil mill wastewater using Ralstonia eutropha.Olive oil mill wastewater (OMW) has a high polluting power, with total phenolics (TP) around 2.5 g l(-1) and chemical oxygen demand (COD) 85 g l(-1). Biological systems offer advantages in treating this type of agro-industrial wastewater. The performance of phenol-adapted Ralstonia eutropha for aerobic biotreatment of OMW has been studied, and a TP concentration of 250 mg l(-1) found to be fully degraded within 24 h. This simple procedure may be adopted as a pretreatment prior to the normal aero ...201121882561
proteomic and transcriptomic elucidation of the mutant ralstonia eutropha g+1 with regard to glucose utilization.by taking advantage of the available genome sequence of ralstonia eutropha h16, glucose uptake in the uv-generated glucose-utilizing mutant r. eutropha g(+)1 was investigated by transcriptomic and proteomic analyses. data revealed clear evidence that glucose is transported by a usually n-acetylglucosamine-specific phosphotransferase system (pts)-type transport system, which in this mutant is probably overexpressed due to a derepression of the encoding nag operon by an identified insertion mutati ...201121278273
iodide accumulation by aerobic bacteria isolated from subsurface sediments of a 129i-contaminated aquifer at the savannah river site, south carolina.(129)i is of major concern because of its mobility in the environment, excessive inventory, toxicity (it accumulates in the thyroid), and long half-life (~16 million years). the aim of this study was to determine if bacteria from a (129)i-contaminated oxic aquifer at the f area of the u.s. department of energy's savannah river site, sc, could accumulate iodide at environmentally relevant concentrations (0.1 µm i(-)). iodide accumulation capability was found in 3 out of 136 aerobic bacterial stra ...201121278282
growth and polyhydroxybutyrate production by ralstonia eutropha in emulsified plant oil medium.polyhydroxyalkanoates (phas) are natural polyesters synthesized by bacteria for carbon and energy storage that also have commercial potential as bioplastics. one promising class of carbon feedstocks for industrial pha production is plant oils, due to the high carbon content of these compounds. the bacterium ralstonia eutropha accumulates high levels of pha and can effectively utilize plant oil. growth experiments that include plant oil, however, are difficult to conduct in a quantitative and rep ...201121279345
evaluation of promoters for gene expression in polyhydroxyalkanoate-producing cupriavidus necator h16.five kinds of promoters were evaluated as tools for regulated gene expression in the pha-producing bacterium cupriavidus necator. several broad-host-range expression vectors were constructed by which expression of a reporter gene gfp was controlled by p(lac), p(tac), or p(bad) derived from escherichia coli, or promoter regions of phac1 (p(phac)) or phap1 (p(phap)) derived from c. necator. then, the gfp-expression profiles were determined in c. necator strains harboring the constructed vectors wh ...201121279346
special content of this issue. “international symposium on biopolymers 2010” (isbp2010). 201121286707
identification of tertiary butyl alcohol (tba)-utilizing organisms in biogac reactors using 13c-dna stable isotope probing.biodegradation of the gasoline oxygenates methyl tertiary-butyl ether (mtbe) and ethyl tertiary-butyl ether (etbe) can cause tertiary butyl alcohol (tba) to accumulate in gasoline-impacted environments. one remediation option for tba-contaminated groundwater involves oxygenated granulated activated carbon (gac) reactors that have been self-inoculated by indigenous tba-degrading microorganisms in ground water extracted from contaminated aquifers. identification of these organisms is important for ...201121286787
versatile metabolic adaptations of ralstonia eutropha h16 to a loss of pdhl, the e3 component of the pyruvate dehydrogenase complex.a previous study reported that the tn5-induced poly(3-hydroxybutyric acid) (phb)-leaky mutant ralstonia eutropha h1482 showed a reduced phb synthesis rate and significantly lower dihydrolipoamide dehydrogenase (dhldh) activity than the wild-type r. eutropha h16 but similar growth behavior. insertion of tn5 was localized in the pdhl gene encoding the dhldh (e3 component) of the pyruvate dehydrogenase complex (pdhc). taking advantage of the available genome sequence of r. eutropha h16, observation ...201121296938
structural and metal binding characterization of the c-terminal metallochaperone domain of membrane fusion protein silb from cupriavidus metallidurans ch34.detoxification of heavy metal ions in proteobacteria is tightly controlled by various systems regulating their sequestration and transport. in cupriavidus metallidurans ch34, a model organism for heavy metal resistance studies, the sil determinant is potentially involved in the efflux of silver and copper ions. proteins sila, silb, and silc form a resistance nodulation cell division (rnd)-based transport system in which silb is the periplasmic adaptor protein belonging to the membrane fusion pro ...201121299248
biosynthesis and characterization of poly (3-hydroxybutyrate-co-3-hydroxyvalerate-co-4-hydroxybutyrate) terpolymer with various monomer compositions by cupriavidus sp. usmaa2-4.poly(3-hydroxybutyrate-co-3-hydroxyvalerate-co-4-hydroxybutyrate) [p(3hb-co-3hv-co-4hb)] terpolymer was produced using cupriavidus sp. usmaa2-4 via one-step cultivation process through combination of various carbon sources such as 1,4-butanediol or ?-butyrolactone with either 1-pentanol, valeric acid, or 1-propanol. oleic acid was added to increase the biomass production. the composition of 3hv and 4hb monomers were greatly affected by the concentration of 1,4-butanediol and 1-pentanol. terpolym ...201121302147
functional cis-expression of phacab genes for poly(3-hydroxybutyrate) production by escherichia coli.to develop a microbial strain producing poly(3-hydroxybutyrate) [p(3hb)], in the absence of antibiotic supplementation (normally required to stabilize a recombinant plasmid), by constructing a recombinant escherichia coli strain with phacab and vgb integrated into the chromosome.201121306405
high-throughput screening of microbial adaptation to environmental stress.we developed a microwell plate, high-throughput, screening method aimed at quantitating the tolerance of a panel of gram-positive and gram-negative bacteria to metals (frankia sp., escherichia coli, cupriavidus metallidurans, rhizobium leguminosarum, and streptomyces scabies). microbial viability was quantified using mts; a tetrazolium salt converted to a water-soluble formazan through microbial reduction. in this paper, we present the stepwise development of the method, highlighting the main el ...201121315114
production of poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate) by ralstonia eutropha from soybean oil.high-yield production of polyhydroxyalkanoates (phas) by ralstonia eutropha kctc 2662 was investigated using soybean oil and ?-butyrolactone as carbon sources. in flask culture, it was shown that r. eutropha kctc 2662 accumulated phas during the growth phase. the optimum carbon to nitrogen ratio (c/n ratio) giving the highest cell and pha yield was 20g-soybean oil/g-(nh(4))(2)so(4). the 4-hydroxybutyrate (4hb) fraction in the copolymer was not strongly affected by the c/n ratio. in a 2.5-l ferme ...201121333767
screening and evaluation of polyhydroxybutyrate-producing strains from indigenous isolate cupriavidus taiwanensis strains.polyhydroxyalkanoate (pha) is a biodegradable material with many potential biomedical applications, including medical implants and drug delivery. this study developed a system for screening production strains in order to optimize pha production in cupriavidus taiwanensis 184, 185, 186, 187, 204, 208, 209 and pseudomona oleovorans atcc 29347. in this study, sudan black b staining, infrared (ir) and gas chromatography (gc) analysis indicated that the best strain for pha synthesis is c. taiwanensis ...201121339985
enzyme mechanism as a kinetic control element for designing synthetic biofuel pathways.living systems have evolved remarkable molecular functions that can be redesigned for in vivo chemical synthesis as we gain a deeper understanding of the underlying biochemical principles for de novo construction of synthetic pathways. we have focused on developing pathways for next-generation biofuels as they require carbon to be channeled to product at quantitative yields. however, these fatty acid-inspired pathways must manage the highly reversible nature of the enzyme components. for targets ...201121358636
a unique iron-sulfur cluster is crucial for oxygen tolerance of a [nife]-hydrogenase.hydrogenases are essential for h(2) cycling in microbial metabolism and serve as valuable blueprints for h(2)-based biotechnological applications. however, most hydrogenases are extremely oxygen sensitive and prone to inactivation by even traces of o(2). the o(2)-tolerant membrane-bound [nife]-hydrogenase of ralstonia eutropha h16 is one of the few examples that can perform h(2) uptake in the presence of ambient o(2). here we show that o(2) tolerance is crucially related to a modification of the ...201121390036
production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from plant oil by engineered ralstonia eutropha strains.the polyhydroxyalkanoate (pha) copolymer poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [p(hb-co-hhx)] has been shown to have potential to serve as a commercial bioplastic. synthesis of p(hb-co-hhx) from plant oil has been demonstrated with recombinant ralstonia eutropha strains expressing heterologous pha synthases capable of incorporating hb and hhx into the polymer. with these strains, however, short-chain-length fatty acids had to be included in the medium to generate pha with high hhx conten ...201121398488
structural basis for metal sensing by cnrx.cnrx is the metal sensor and signal modulator of the three-protein transmembrane signal transduction complex cnryxh of cupriavidus metallidurans ch34 that is involved in the setup of cobalt and nickel resistance. we have determined the atomic structure of the soluble domain of cnrx in its ni-bound, co-bound, or zn-bound form. ni and co ions elicit a biological response, while the zn-bound form is inactive. the structures presented here reveal the topology of intraprotomer and interprotomer inter ...201121414325
the crystal structure of cupriavidus necator nitrate reductase in oxidized and partially reduced states.the periplasmic nitrate reductase (napab) from cupriavidus necator is a heterodimeric protein that belongs to the dimethyl sulfoxide reductase family of mononuclear mo-containing enzymes and catalyzes the reduction of nitrate to nitrite. the protein comprises a large catalytic subunit (napa, 91 kda) containing the molybdenum active site plus one [4fe-4s] cluster, as well as a small subunit (napb, 17 kda), which is a diheme c-type cytochrome involved in electron transfer. crystals of the oxidized ...201121419779
functional metagenomics of methylotrophs.it is widely recognized that most microbes in the biosphere remain uncultured and unknown. in the recent few years, whole genome shotgun (wgs) sequencing of environmental dna (metagenomics) has revolutionized the field of environmental microbiology by allowing one to tap into the genomic content of microbial communities in specific ecological niches, deducing information on their biochemical potentials. however, ascribing specific functions to specific organisms remains very difficult in most ca ...201121419916
[a case report of wautersia sepsis infection].genus wautersia is a gram-negative bacterium that has rarely been associated with human infections abroad, and is firstly reported in home. we report a case of sepsis caused by wautersia species, which was separated from blood and bone marrows.201121421507
characterization of the metabolically modified heavy metal-resistant cupriavidus metallidurans strain msr33 generated for mercury bioremediation.mercury-polluted environments are often contaminated with other heavy metals. therefore, bacteria with resistance to several heavy metals may be useful for bioremediation. cupriavidus metallidurans ch34 is a model heavy metal-resistant bacterium, but possesses a low resistance to mercury compounds.201121423734
the maturation factors hoxr and hoxt contribute to oxygen tolerance of membrane-bound [nife] hydrogenase in ralstonia eutropha h16.the membrane-bound [nife] hydrogenase (mbh) of ralstonia eutropha h16 undergoes a complex maturation process comprising cofactor assembly and incorporation, subunit oligomerization, and finally twin-arginine-dependent membrane translocation. due to its outstanding o(2) and co tolerance, the mbh is of biotechnological interest and serves as a molecular model for a robust hydrogen catalyst. adaptation of the enzyme to oxygen exposure has to take into account not only the catalytic reaction but als ...201121441514
strict and direct transcriptional repression of the poba gene by benzoate avoids 4-hydroxybenzoate degradation in the pollutant degrader bacterium cupriavidus necator jmp134.as other environmental bacteria, cupriavidus necator jmp134 uses benzoate as preferred substrate in mixtures with 4-hydroxybenzoate, strongly inhibiting its degradation. the mechanism underlying this hierarchical use was studied. a c. necator bena mutant, defective in the first step of benzoate degradation, is unable to metabolize 4-hydroxybenzoate when benzoate is also included in the medium, indicating that this substrate and not one of its catabolic intermediates is directly triggering repres ...201121450007
expanding the chiral pool: oxidation of meta-bromobenzoic acid by r. eutrophus b9 allows access to new reaction manifolds.metabolism of meta-bromobenzoic acid by the blocked mutant ralstonia eutrophus b9 affords an enantiopure dearomatised halodiene-diol which we demonstrate is a versatile chiron for organic synthesis. the presence of the halogen leads to reactivity that is distinct to that observed for the non-halogenated analogue and also serves as a synthetic handle for further functionalisation.201121472181
effects of homologous phosphoenolpyruvate-carbohydrate phosphotransferase system proteins on carbohydrate uptake and poly(3-hydroxybutyrate) accumulation in ralstonia eutropha h16.seven gene loci encoding putative proteins of the phosphoenolpyruvate-carbohydrate phosphotransferase system (pep-pts) were identified in the genome of ralstonia eutropha h16 by in silico analysis. except the n-acetylglucosamine-specific pep-pts, an additional complete pep-pts is lacking in strain h16. based on these findings, we generated single and multiple deletion mutants defective mainly in the pep-pts genes to investigate their influence on carbon source utilization, growth behavior, and p ...201121478317
size control and catalytic activity of bio-supported palladium nanoparticles.the development of nanoparticles has greatly improved the catalytic properties of metals due to the higher surface to volume ratio of smaller particles. the production of nanoparticles is most commonly based on abiotic processes, but in the search for alternative protocols, bacterial cells have been identified as excellent scaffolds of nanoparticle nucleation, and bacteria have been successfully employed to recover and regenerate platinum group metals from industrial waste. we report on the form ...201121481574
continuous production of poly([r]-3-hydroxybutyrate) by cupriavidus necator in a multistage bioreactor cascade.poly(hydroxyalkanoates) (phas) constitute biodegradable polyesters and are considered among the most promising candidates to replace common petrochemical plastics in various applications. to date, all commercial processes for pha production employ microbial discontinuous fed-batch fermentations. these processes feature drawbacks such as varying product quality and the inevitable periods of downtime for preparation and post-treatment of the bioreactor equipment. an unprecedented approach to pha p ...201121503760
engineering of polyhydroxyalkanoate (pha) synthase phac2(ps) of pseudomonas stutzeri via site-specific mutation for efficient production of pha copolymers.the site-specific mutagenesis for pha synthase phac2(ps1317) from pseudomonas stutzeri 1317 was conducted for optimizing production of short-chain-length and medium-chain-length polyhydroxyalkanoates (scl-mcl pha). recombinant ralstonia eutropha phb-4 harboring double mutated phac2 ( ps1317 ) gene (phac2 ( ps ) qkst) produced 42 wt.% pha content in the cell dry weight (cdw) with 93 mol% 3-hydroxybutyrate (hb) as monomer in the pha copolymer. compared to that of wild-type phac2 ( ps1317 ), the hi ...201121509565
cloning and characterization of an epoxide hydrolase from cupriavidus metallidurans-ch34.a putative epoxide hydrolase-encoding gene was identified from the genome sequence of cupriavidus metallidurans ch34. the gene was cloned and overexpressed in escherichia coli with his(6)-tag at its n-terminus. the epoxide hydrolase (cmeh) was purified to near homogeneity and was found to be a homodimer, with subunit molecular weight of 36kda. the cmeh had broad substrate specificity as it could hydrolyze 13 epoxides, out of 15 substrates tested. cmeh had high specific activity with 1,2-epoxyoct ...201121515382
establishment of an alternative phosphoketolase-dependent pathway for fructose catabolism in ralstonia eutropha h16.the β-proteobacterium ralstonia eutropha h16 utilizes fructose and gluconate as carbon sources for heterotrophic growth exclusively via the entner-doudoroff pathway with its key enzyme 2-keto-3-deoxy-6-phosphogluconate (kdpg) aldolase. by deletion of the responsible gene eda, we constructed a kdpg aldolase-negative strain, which is disabled to supply pyruvate for energy metabolism from fructose or gluconate as sole carbon sources. to restore growth on fructose, an alternative pathway, similar to ...201121519932
biochemical characterization of ethanol-dependent reduction of furfural by alcohol dehydrogenases.lignocellulosic biomass is usually converted to hydrolysates, which consist of sugars and sugar derivatives, such as furfural. before yeast ferments sugars to ethanol, it reduces toxic furfural to non-inhibitory furfuryl alcohol in a prolonged lag phase. bioreduction of furfural may shorten the lag phase. cupriavidus necator jmp134 rapidly reduces furfural with a zn-dependent alcohol dehydrogenase (furx) at the expense of ethanol (li et al. 2011). the mechanism of the ethanol-dependent reduction ...201121526389
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