| organization of polyhydroxyalkanoate synthase for in vitro polymerization as revealed by atomic force microscopy. | individual polyhydroxyalkanoate synthase molecules from ralstonia eutropha (phacre) were directly visualized on highly oriented pyrolytic graphite (hopg) by atomic force microscopy (afm). phacre molecule was observed as a spherical particle of 2.9 +/- 0.4 nm in height and 28 +/- 4 nm in width. in vitro polymerization reaction on hopg was carried out for 5 min by reacting the phacre molecules with (r)-3-hydroxybutyryl-coa monomers. the reaction product was then observed after the removal of water ... | 2005 | 16208629 |
| production of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) from gluconate and glucose by recombinant aeromonas hydrophila and pseudomonas putida. | aeromonas hydrophila 4ak4 and pseudomonas putida gpp104 were genetically engineered to synthesize poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (phbhhx) using gluconate and glucose rather than fatty acids. a truncated tesa gene, encoding cytosolic thioesterase i of escherichia coli which catalyzes the conversion of acyl-acp into free fatty acids, was introduced into a. hydrophila 4ak4. when grown in gluconate, the recombinant a. hydrophila 4ak4 synthesized 10% (w/w) phbhhx containing 14% (mol/mo ... | 2005 | 16215853 |
| repeated batch cultivation of ralstonia eutropha for poly (beta-hydroxybutyrate) production. | batch cultivation of ralstonia eutropha nrrl b14690 attained 21 g biomass l(-1) and 9.4 g poly(beta-hydroxybutyrate) l(-1) (0.45 g phb g(-1 )dry wt(-1)) in 60 h. repeated batch operation (empty-and-fill protocol) to remove 20% (v/v) of the culture broth and to supplement an equal volume of fresh media resulted in 49 g biomass l(-1) and 25 g phb l(-1) (0.51 g phb g(-1) dry wt(-1)) with an overall productivity of 0.42 g phb l(-1 )h(-1 )in 67 h. in the two cycles of repeated batch fermentation ther ... | 2005 | 16215857 |
| biosynthesis and characterization of poly(3-hydroxybutyrate-co-3- hydroxyhexanoate) from palm oil products in a wautersia eutropha mutant. | palm kernel oil, palm olein, crude palm oil and palm acid oil were used for the synthesis of poly (3-hydroxybutyrate-co-3-hydroxyhexanoate) [p(3hb-co-3hhx)] by a mutant strain of wautersia eutropha (formerly ralstonia eutropha) harboring the aeromonas caviae polyhydroxyalkanoate (pha) synthase gene. palm kernel oil was an excellent carbon source for the production of cell biomass and p(3hb-co-3hhx). about 87% (w/w) of the cell dry weight as p(3hb-co-3hhx) was obtained using 5 g palm kernel oil/l ... | 2005 | 16215858 |
| enzymatic synthesis of poly(3-hydroxybutyrate-co-4-hydroxybutyrate) with coa recycling using polyhydroxyalkanoate synthase and acyl-coa synthetase. | we succeeded in developing a novel method for in vitro poly(3-hydroxybutyrate-co-4-hydroxybutyrate) [p(3 hb-co-4 hb)] synthesis with coa recycling using polyhydroxyalkanoate synthase and an acyl-coa synthetase. using this method, the monomer compositions in p(3 hb-co-4 hb)s could be controlled strictly by the ratios of the monomers in the reaction mixtures. | 2005 | 16233824 |
| production and purification of self-assembling peptides in ralstonia eutropha. | self-assembling peptides have emerged as an attractive scaffold material for tissue engineering, yet the expense associated with solid phase chemical synthesis has limited their broad use. in addition, the fidelity of chemical synthesis constrains the length of polypeptides that can be produced homogeneously by this method. template-derived biosynthesis by recombinant dna technology may overcome both of these problems. however, recovery of polypeptides from recombinant protein expression systems ... | 2006 | 16249097 |
| enzymatic recovery and purification of polyhydroxybutyrate produced by ralstonia eutropha. | polyhydroxybutyrate (phb) is the most studied among a wide variety of polyhydroxyalkanoates, bacterial biodegradable polymers known as potential substitutes for conventional plastics. this work aimed at evaluating the use of enzymes to recover and purify the phb produced by ralstonia eutropha dsm545. screening experiments allowed the selection of trypsin, bromelain and lysozyme among six enzymes, based on their efficiency in lysing cells of a non-phb producing r. eutropha strain. then, process c ... | 2006 | 16253372 |
| electrocatalytic hydrogen oxidation by an enzyme at high carbon monoxide or oxygen levels. | use of hydrogen in fuel cells requires catalysts that are tolerant to oxygen and are able to function in the presence of poisons such as carbon monoxide. hydrogen-cycling catalysts are widespread in the bacterial world in the form of hydrogenases, enzymes with unusual active sites composed of iron, or nickel and iron, that are buried within the protein. we have established that the membrane-bound hydrogenase from the beta-proteobacterium ralstonia eutropha h16, when adsorbed at a graphite electr ... | 2005 | 16260746 |
| application of a kdpg-aldolase gene-dependent addiction system for enhanced production of cyanophycin in ralstonia eutropha strain h16. | two different recombinant plasmids both containing the cyanophycin synthetase gene (cpha) of synechocystis sp. strain pcc6308 but differing concerning the resistance marker gene were tested for their suitability to produce high amounts of cyanophycin in recombinant strains of ralstonia eutropha. various cultivation experiments at the 30-l scale revealed very low cyanophycin contents of the cells ranging from 4.6% to 6.2% (w/w) of cellular dry weight (cdw) only, most probably because most cells h ... | 2006 | 16266816 |
| proof that burkholderia strains form effective symbioses with legumes: a study of novel mimosa-nodulating strains from south america. | twenty mimosa-nodulating bacterial strains from brazil and venezuela, together with eight reference mimosa-nodulating rhizobial strains and two other beta-rhizobial strains, were examined by amplified rrna gene restriction analysis. they fell into 16 patterns and formed a single cluster together with the known beta-rhizobia, burkholderia caribensis, burkholderia phymatum, and burkholderia tuberum. the 16s rrna gene sequences of 15 of the 20 strains were determined, and all were shown to belong t ... | 2005 | 16269788 |
| dispersion optimization to enhance phb production in fed-batch cultures of ralstonia eutropha. | despite its many useful properties, microbial production of poly-beta-hydroxybutyrate (phb) is not yet commercially competitive with synthetic polymers. one reason is inadequate optimization of the fermentation under industrial conditions. in this study, a physiologically reasonable and experimentally validated kinetic model for phb synthesis by ralstonia eutropha was incorporated into a dispersion model to simulate a large fed-batch bioreactor. solutions of the model indicated that cell growth ... | 2006 | 16289872 |
| beta-rhizobia from mimosa pigra, a newly discovered invasive plant in taiwan. | a total of 191 rhizobial isolates from the root nodules of three geographically separate populations of the invasive plant mimosa pigra in taiwan were examined using amplified rdna restriction analysis, 16s rdna sequences, protein profiles and elisa. of these, 96% were identified as burkholderia and 4% as cupriavidus taiwanensis. the symbiosis-essential genes noda and nifh were present in two strains of burkholderia (pas44 and ptk47), and in one of c. taiwanensis (pas15). all three could nodulat ... | 2005 | 16313648 |
| staining and quantification of poly-3-hydroxybutyrate in saccharomyces cerevisiae and cupriavidus necator cell populations using automated flow cytometry. | poly [(r)-3-hydroxybutyric acid] (phb) is a prokaryote storage material for carbon and energy that accumulates in cells under unbalanced growth conditions. because this class of biopolymers has plastic-like properties, it has attracted considerable interest for biomedical applications and as a biodegradable commodity plastic. current flow cytometric techniques to quantify intracellular phb are based on nile red. here, an improved cytometric technique for cellular phb quantification utilizing bod ... | 2006 | 16342115 |
| response in soil of cupriavidus necator and other copper-resistant bacterial predators of bacteria to addition of water, soluble nutrients, various bacterial species, or bacillus thuringiensis spores and crystals. | soil was incubated with various species of bacteria, bacillus subtilis, or bacillus thuringiensis spores and crystals. these were added to serve as potential prey for indigenous, copper-resistant, nonobligate bacterial predators of bacteria in the soil. alternatively, the soil was incubated with soluble nutrients or water only to cause potential indigenous prey cells to multiply so the predator cells would multiply. all of these incubation procedures caused excessive multiplication of some gram- ... | 1988 | 16347727 |
| protozoan response to the addition of bacterial predators and other bacteria to soil. | representatives of several categories of bacteria were added to soil to determine which of them might elicit responses from the soil protozoa. the various categories were nonobligate bacterial predators of bacteria, prey bacteria for these predators, indigenous bacteria that are normally present in high numbers in soil, and non-native bacteria that often find their way in large numbers into soil. the soil was incubated and the responses of the indigenous protozoa were determined by most-probable ... | 1989 | 16347983 |
| competitive ability and survival in soil of pseudomonas strain 679-2, a dominant, nonobligate bacterial predator of bacteria. | a copper-resistant, nonobligate, bacterial predator of bacteria was isolated from soil. it was a pseudomonas species, designated strain 679-2. it attacked most other nonobligate bacterial predators and hence could control their predatory and other activities in nature. it also inhibited various fungi. it attached to prey cells and produced a toxic, copper-related, growth initiation factor like that produced by cupriavidus necator. in addition, it produced a second, novel compound that was both a ... | 1992 | 16348631 |
| comparative study of promoters for the production of polyhydroxyalkanoates in recombinant strains of wautersia eutropha. | recombinant strains of wautersia eutropha expressing an artificial polyhydroxyalkanoate (pha) biosynthesis operon under the control of different native promoters linked to polyhydroxybutyrate (phb) (p(phb)), acetoin (p(acoe), p(acod), and p(acox)) or pyruvate (p(pdhe)) metabolism were constructed and tested. the promoters were representative either of the enterobacterial sigma70 (p(phb), p(acoe), and p(pdhe))- or sigma54 (p(acod) and p(acox))-dependent promoters. to obtain polymers consisting of ... | 2006 | 16362422 |
| the effects of cyanobacterial exudates on bacterial growth and biodegradation of organic contaminants. | the pulp and paper industry largely depends on the biodegradation activities of heterotrophic bacteria to remove organic contaminants in wastewater prior to discharge. our recent discovery of extensive cyanobacterial communities in pulp and paper waste treatment systems led us to investigate the potential impacts of cyanobacterial exudates on growth and biodegradation efficiency of three bacterial heterotrophs. each of the three assessed bacteria represented different taxa commonly found in pulp ... | 2006 | 16382284 |
| precipitation of silver-thiosulfate complex and immobilization of silver by cupriavidus metallidurans ch34. | cupriavidus metallidurans ch34 is a facultative chemolithotrophic bacterium that possesses two megaplasmids (pmol28 and pmol30) that confer resistance to eleven metals. the ability of cupriavidus metallidurans ch34 to resist silver is described here. electronic microscopy, energy-dispersive x-ray (edx) and x-ray diffractometry (drx) observations revealed that c. metallidurans ch34 strongly associated silver with the outer membrane, under chloride chemical form. using derivate strains of c. metal ... | 2005 | 16388403 |
| [physiological and biochemical characteristics and capacity for polyhydroxyalkanoates synthesis in a glucose-utilizing strain of hydrogen-oxidizing bacteria, ralstonia eutropha b8562]. | the physiological, biochemical, genetic, and cultural characteristics of the glucose-utilizing mutant strain ralstonia eutropha b8562 were investigated in comparison with the parent strain r. eutropha b5786. the morphological, cultural, and biochemical characteristics of strain r. eutropha b8562 were similar to those of strain r. eutropha b5786. genetic analysis revealed differences between the 16s rrna gene sequences of these strains. the growth characteristics of the mutant using glucose as th ... | 2005 | 16400989 |
| influence of temperature on process efficiency and microbial community response during the biological removal of chlorophenols in a packed-bed bioreactor. | two reactors, initially operated at 14 and 23+/-1 degrees c (ra and rb, respectively), were inoculated with a bacterial consortium enriched and acclimatized to the respective temperatures over 4 months. the biofilms, formed in the reactors, were studied using scanning electron microscopy, cultivation of the biofilm microflora, and physiological analysis of the isolates. two bacteria able to mineralize chlorophenols under a large range of temperature (10-30 degrees c) were isolated from the biofi ... | 2006 | 16402167 |
| bioluminescent monitoring of turbulent bioconvection. | under adjusted experimental conditions, open-to-air cultures of lux gene-engineered ralstonia eutropha (wholecell biosensors of copper) exhibit bioconvection, which accounts for fluctuating bioluminescence. the power spectrum of bioluminescence intensity fluctuations recorded from a cylindrical sample 9 mm in diameter and approximately 10 mm in height is characterized by a dominant low-frequency oscillation (with a characteristic period of approximately 8-12 min), which is occasionally accompani ... | 2006 | 16416487 |
| no-dependent transcriptional activation of gene expression in ralstonia eutropha h16. | the sigma54-dependent transcriptional regulator norr of ralstonia eutropha h16 activates gene expression in response to nitric oxide (no). the n-terminal domain of norr is thought to be involved in signal perception. a c112s exchange within this domain abolished promoter activation by the mutated protein, indicating that cys(112) is essential for the signalling mechanism of norr. the dna region recognized by norr contains three copies of a conserved element termed the norr-box. alteration of bas ... | 2006 | 16417516 |
| an improved purification procedure for the soluble [nife]-hydrogenase of ralstonia eutropha: new insights into its (in)stability and spectroscopic properties. | infrared (ir) spectra in combination with chemical analyses have recently shown that the active ni-fe site of the soluble nad(+)-reducing [nife]-hydrogenase from ralstonia eutropha contains four cyanide groups and one carbon monoxide as ligands. experiments presented here confirm this result, but show that a variable percentage of enzyme molecules loses one or two of the cyanide ligands from the active site during routine purification. for this reason the redox conditions during the purification ... | 2006 | 16418856 |
| real-time analysis of enzymatic surface-initiated polymerization using surface plasmon resonance (spr). | the kinetics of enzymatic surface-initiated polymerization of phb on gold surface has been examined by spr and the resultant polymer layers characterized by afm and ft-ir spectrometry. the immobilized enzyme catalyzed surface-initiated polymerization of 3hb-coa, resulting in the formation of a polymer brush on the surface. the rate of polymer growth from the surface was monitored by spr in real-time. polymer growth as measured by the increase in the resonance angle showed no apparent lag phase d ... | 2006 | 16432845 |
| optimization of cyanophycin production in recombinant strains of pseudomonas putida and ralstonia eutropha employing elementary mode analysis and statistical experimental design. | elementary mode analysis was applied to simulate conditions for cyanophycin (cgp) biosynthesis and to optimize its production in bacteria. the conclusions from these simulations were confirmed by experiments with recombinant strains of the wild types and polyhydroxyalkanoate (pha)-negative mutants of ralstonia eutropha and pseudomonas putida expressing cgp synthetase genes (cpha) of synechocystis sp. strain pcc6308 or anabaena sp. strain pcc7120. in particular, the effects of suitable precursor ... | 2006 | 16435401 |
| coexistence of burkholderia, cupriavidus, and rhizobium sp. nodule bacteria on two mimosa spp. in costa rica. | rrna gene sequencing and pcr assays indicated that 215 isolates of root nodule bacteria from two mimosa species at three sites in costa rica belonged to the genera burkholderia, cupriavidus, and rhizobium. this is the first report of cupriavidus sp. nodule symbionts for mimosa populations within their native geographic range in the neotropics. burkholderia spp. predominated among samples from mimosa pigra (86% of isolates), while there was a more even distribution of cupriavidus, burkholderia, a ... | 2006 | 16461667 |
| degradation of 4-chloro-2-methylphenoxyacetic acid in top- and subsoil is quantitatively linked to the class iii tfda gene. | the tfda gene is known to be involved in the first step of the degradation of the phenoxy acid herbicide 4-chloro-2-methylphenoxyacetic acid (mcpa) in several soil bacteria, but bacteria containing other tfda-like genes have been isolated as well. a quantitative real-time pcr method was used to monitor the increase in the concentration of tfda genes during degradation of mcpa in sandy topsoil and subsoil over a period of 115 days. quantitative pcr revealed growth in the tfda-containing bacterial ... | 2006 | 16461702 |
| a lower specificity phac2 synthase from pseudomonas stutzeri catalyses the production of copolyesters consisting of short-chain-length and medium-chain-length 3-hydroxyalkanoates. | a polyhydroxyalkanoate (pha) synthase gene phac2 (ps) from pseudomonas stutzeri strain 1317 was introduced into a pha synthase gene phbc (re) negative mutant, ralstonia eutropha phb(-)4. it conferred on the host strain the ability to synthesize pha, the monomer compositions of which varied widely when grown on different carbon sources. during cultivation on gluconate, the presence of phac2 (ps) in r. eutropha phb(-)4 led to the accumulation of polyhydroxybutyrate (phb) homopolymer in an amount o ... | 2006 | 16496091 |
| overexpression, purification, crystallization and crystallographic analysis of copk of cupriavidus metallidurans. | copk of cupriavidus metallidurans is a 93-amino-acid protein whose mature form (73 amino acids) has been purified and crystallized by the hanging-drop vapour-diffusion method in 100 mm citrate ph 3.5, 200 mm li2so4, 20%(w/v) glycerol, 13%(w/v) peg 8000. crystals display orthorhombic symmetry, with unit-cell parameters a = 57.53, b = 128.65, c = 49.77 a, and diffract to 2.2 a resolution using synchrotron radiation. | 2005 | 16511169 |
| effects of recombinant precursor pathway variations on poly[(r)-3-hydroxybutyrate] synthesis in saccharomyces cerevisiae. | different recombinant r-3-hydroxybutyryl-coa (3-hb) synthesis pathways strongly influenced the rate and accumulation of the biopolymer poly[(r)-3-hydroxybutyrate] (phb) in saccharomyces cerevisiae. it has been previously shown that expression of the cupriavidus necator phb synthase gene leads to phb accumulation in s. cerevisiae [leaf, t., peterson, m., stoup, s., somers, d., srienc, f., 1996. saccharomyces cerevisiae expressing bacterial polyhydroxybutyrate synthase produces poly-3-hydroxybutyr ... | 2006 | 16530287 |
| thiolysis of poly(3-hydroxybutyrate) with polyhydroxyalkanoate synthase from ralstonia eutropha. | poly(3-hydroxybutyrate) (phb) is synthesized from 3-hydroxybutyryl-coa by polyhydroxyalkanoate synthase and hydrolyzed by phb depolymerase. in this study, we focused on the reverse reaction of polyhydroxyalkanoate synthase, and propose the possibility that phb can be degraded through a novel process, that is thiolysis of phb with coash. polyhydroxyalkanoate synthase of ralstonia eutropha was incubated with 14c-labeled phb and coash. the reaction mixture was fractionated by hplc and then analyzed ... | 2006 | 16567428 |
| zinc sorption to three gram-negative bacteria: combined titration, modeling, and exafs study. | the acid-base and zn sorption properties of three bacteria, cupriavidus metallidurans ch34, pseudomonas putida atcc12633, and escherichia coli k12dh5alpha, were investigated through an original combination of extended x-ray absorption fine structure (exafs) spectroscopy and equilibrium titration studies. acid-base titration curves of the three strains were fitted with a model accounting for three conceptual reactive sites: an acidic (carboxyl and/or phosphodiester), a neutral (phosphomonoester), ... | 2006 | 16570601 |
| characterization of poly(3-hydroxybutyrate) produced by cupriavidus necator in solid-state fermentation. | solid-state fermentation (ssf) has recently been proposed as an alternative to submerged fermentation for the production of poly(hydroxyalkanoates). in the present work, x-ray diffraction, differential scanning calorimetry, nuclear magnetic resonance and infrared spectroscopy were employed to investigate the chemical structure, as well as the thermal properties and the crystalline morphology of poly(3-hydroxybutyrate) samples produced by ssf, using as raw material either soy cake or soy cake sup ... | 2007 | 16580194 |
| rrna and poly-beta-hydroxybutyrate dynamics in bioreactors subjected to feast and famine cycles. | feast and famine cycles are common in activated sludge wastewater treatment systems, and they select for bacteria that accumulate storage compounds, such as poly-beta-hydroxybutyrate (phb). previous studies have shown that variations in influent substrate concentrations force bacteria to accumulate high levels of rrna compared to the levels in bacteria grown in chemostats. therefore, it can be hypothesized that bacteria accumulate more rrna when they are subjected to feast and famine cycles. how ... | 2006 | 16597926 |
| chlorophenol hydroxylases encoded by plasmid pjp4 differentially contribute to chlorophenoxyacetic acid degradation. | phenoxyalkanoic compounds are used worldwide as herbicides. cupriavidus necator jmp134(pjp4) catabolizes 2,4-dichlorophenoxyacetate (2,4-d) and 4-chloro-2-methylphenoxyacetate (mcpa), using tfd functions carried on plasmid pjp4. tfda cleaves the ether bonds of these herbicides to produce 2,4-dichlorophenol (2,4-dcp) and 4-chloro-2-methylphenol (mcp), respectively. these intermediates can be degraded by two chlorophenol hydroxylases encoded by the tfdb(i) and tfdb(ii) genes to produce the respect ... | 2006 | 16597983 |
| cost-effective recovery and purification of polyhydroxyalkanoates by selective dissolution of cell mass. | highly efficient separation and purification of polyhydroxyalkanoates (phas) from pha-containing cell mass is essential to production of the bioplastics from renewable resources in a cost-effective, environmentally friendly way. based on selective dissolution of non-pha cell mass (npcm) by protons in aqueous solution and crystallization kinetics of pha biopolymers, a simple process is developed and demonstrated to recover phas from cell mass to high purity (>97 wt %) with high yield (>95 wt %). ... | 2006 | 16599575 |
| cupriavidus pinatubonensis sp. nov. and cupriavidus laharis sp. nov., novel hydrogen-oxidizing, facultatively chemolithotrophic bacteria isolated from volcanic mudflow deposits from mt. pinatubo in the philippines. | taxonomic studies were performed on ten hydrogen-oxidizing, facultatively chemolithotrophic bacteria that were isolated from volcanic mudflow deposits derived from the eruption of mt. pinatubo in the philippines in 1991. phylogenetic analysis based on 16s rrna gene sequences indicated that these isolates belonged to the genus cupriavidus of the betaproteobacteria; sequence similarity values with their nearest phylogenetic neighbour, cupriavidus basilensis, were 97.1-98.3 %. in addition to phylog ... | 2006 | 16627640 |
| coph from cupriavidus metallidurans ch34. a novel periplasmic copper-binding protein. | the coph gene is one of the 19 open reading frames (orfs) found in the cop cluster borne by the large plasmid pmol30 in cupriavidus metallidurans ch34. the entire cluster is involved in detoxification of copper from the cytoplasm as well as from the periplasm. the function of the corresponding protein, coph, is not yet clear, but it seems to be involved in the late response phase. we have cloned coph and overproduced and purified the corresponding protein. coph is rather unique as only one paral ... | 2006 | 16634637 |
| [nife]-hydrogenases of ralstonia eutropha h16: modular enzymes for oxygen-tolerant biological hydrogen oxidation. | recent research on hydrogenases has been notably motivated by a desire to utilize these remarkable hydrogen oxidation catalysts in biotechnological applications. progress in the development of such applications is substantially hindered by the oxygen sensitivity of the majority of hydrogenases. this problem tends to inspire the study of organisms such as ralstonia eutropha h16 that produce oxygen-tolerant [nife]-hydrogenases. r. eutropha h16 serves as an excellent model system in that it produce ... | 2005 | 16645314 |
| mutation on n-terminus of polyhydroxybutyrate synthase of ralstonia eutropha enhanced phb accumulation. | polyhydroxyalkanoate (pha) synthase is the central enzyme involved in the biosynthesis of pha, a family of bacterial biodegradable polyesters. due to its high variability, the n-terminal fragment of this enzyme was previously considered as unnecessary for a functionally active enzyme. in this study, polyhydroxybutyrate synthase from ralstonia eutropha (phbc(re)) with a deletion on n-terminal 88 amino acid residues showed a significant reduced activity, as reflected by only 1.5% phb accumulation ... | 2006 | 16673109 |
| modeling and optimization of biopolymer (polyhydroxyalkanoates) production from ice cream residue by novel statistical experimental design. | polyhydroxyalkanoates (phas) are thermoplastic polyesters synthesized by ralstonia eutropha and other bacteria as a form of intracellular carbon and energy storage and are accumulated as lipid inclusions in the cytoplasm of these bacteria. the modeling and optimization of pha production by fermentation from industrial waste (ice cream residue) was studied by employing statistical experimental design methods. a series of iterative experimental designs was used to find optimal factor conditions (m ... | 2006 | 16702606 |
| transcriptomic and proteomic analyses of the pmol30-encoded copper resistance in cupriavidus metallidurans strain ch34. | the four replicons of cupriavidus metallidurans ch34 (the genome sequence was provided by the us department of energy-university of california joint genome institute) contain two gene clusters putatively encoding periplasmic resistance to copper, with an arrangement of genes resembling that of the copsrabcd locus on the 2.1 mb megaplasmid (mpl) of ralstonia solanacearum, a closely related plant pathogen. one of the copsrabcd clusters was located on the 2.6 mb mpl, while the second was found on t ... | 2006 | 16735739 |
| preliminary electrochemical studies of the flavohaemoprotein from ralstonia eutropha entrapped in a film of methyl cellulose: activation of the reduction of dioxygen. | a flavohaemoprotein (fhp) from ralstonia eutropha, obtained in a pure and active form, has been entrapped in a film of methyl cellulose on the electrode surface and gives a stable and reproducible electrochemical response at ph 7.00 when subject to cyclic voltammetry using a glassy carbon electrode. to our knowledge, no previous direct electrochemistry had been achieved with a bacterial flavohaemoglobin, which possess both a fad and a haem. a single couple is observed which is assigned to the ha ... | 2007 | 16750432 |
| new recombinant escherichia coli strain tailored for the production of poly(3-hydroxybutyrate) from agroindustrial by-products. | a recombinant e. coli strain (k24k) was constructed and evaluated for poly(3-hydroxybutyrate) (phb) production from whey and corn steep liquor as main carbon and nitrogen sources. this strain bears the pha biosynthetic genes from azotobacter sp. strain fa8 expressed from a t5 promoter under the control of the lactose operator. k24k does not produce the lactose repressor, ensuring constitutive expression of genes involved in lactose transport and utilization. phb was efficiently produced by the r ... | 2006 | 16751501 |
| bacterial synthesis of pha block copolymers. | polyhydroxyalkanoates (pha) containing block copolymers were synthesized in cupriavidus necator using periodic substrate addition. poly(3-hydroxybutyrate) (phb) segments were formed during fructose utilization. pulse feeds of pentanoic acid resulted in the synthesis of 3-hydroxyvalerate monomers, forming poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (phbv) random copolymer. pha synthesis was controlled using analysis of oxygen uptake and carbon evolution rates from the bioreactor off-gas. a combi ... | 2006 | 16768413 |
| proteomic examination of ralstonia eutropha in cellular responses to formic acid. | in this study, ralstonia eutropha was used to elucidate protein changes in response to formic acid. sixty-three differentially expressed proteins in relation to formic acid in r. eutropha were found with 1-d page and nano-lc-ms/ms. among the proteins with decreased expression, four were involved in the shikimate pathway and three proteins in the pyrimidine biosynthesis pathway. with the increased expression of proteins, a dramatic change occurred in the induction of ion transporters in relation ... | 2006 | 16807942 |
| evaluation of pyrrolidonyl arylamidase for the identification of nonfermenting gram-negative rods. | to evaluate the activity of pyrrolidonyl arylamidase (pyr) for the differentiation and identification of nonfermenting gram negative rods (nfgnr), 293 isolates were tested. a 24 h culture of each test organism was prepared. from this a 108-109 cfu/ml suspension was added to 0.25 ml of sterile physiologic solution. a pyr disk was then added and the test was incubated for 30 minutes at 35-37 degrees c, at environmental atmosphere. reading was done by adding 1 drop of cinnamaldehyde reagent. strain ... | 2007 | 16822636 |
| paralogs of genes encoding metal resistance proteins in cupriavidus metallidurans strain ch34. | cupriavidus (wautersia, ralstonia, alcaligenes) metallidurans strain ch34is a well-studied example of a metal-resistant proteobacterium. genome sequence analysis revealed the presence of a variety of paralogs of proteins that were previously shown to be involved in heavy metal resistance. which advantage has c. metallidurans in maintaining all these paralogs during evolution? paralogs investigated belong to the families rnd (resistance nodulation cell division) or chr (chromate resistance). the ... | 2006 | 16825791 |
| sequence distribution in microbial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) co-polyesters determined by nmr and ms. | the microstructure of bacterial poly(3-hydroxybutyrate-co-3-hydroxyvalerate) copolyesters (phbv) as well as a mixture of two phbv copolyesters of different comonomer composition and sequence distribution was studied by 13c nmr based on dyad and triad analysis and multistage electrospray ionization mass spectrometry (esi-msn). both techniques gave results that were in good agreement for all investigated samples. the effect of microstructure on phbv thermal properties was investigated from the mel ... | 2006 | 16827589 |
| metabolic engineering of strains of ralstonia eutropha and pseudomonas putida for biotechnological production of 2-methylcitric acid. | in this study strains of ralstonia eutropha h16 and pseudomonas putida kt2440 were engineered which are suitable for biotechnological production of 2-methylcitric acid (2mc). analysis of a previous mutant of r. eutropha able to accumulate 2mc recommended this strain as a candidate for fermentative production of 2mc. this knowledge was used for construction of strains of r. eutropha h16 and p. putida kt2440 capable of enhanced production of 2mc. in both bacteria the chromosomal genes encoding the ... | 2006 | 16876450 |
| construction of recombinant bacillus subtilis for production of polyhydroxyalkanoates. | polyhydroxyalkanoates (phas) are polyesters of hydroxyalkanoates synthesized by numerous bacteria as intracellular carbon and energy storage compounds and accumulated as granules in the cytoplasm of cells. in this work, we constructed two recombinant plasmids, pbe2c1 and pbe2c1ab, containing one or two pha synthse genes, respectively. the two plasmids were inserted into bacillus subtilis db104 to generate modified strains, b. subtilis/pbe2c1 and b. subtilis/pbe2c1ab. the two recombinants strains ... | 2006 | 16915708 |
| recombinant escherichia coli strain produces a zz domain displaying biopolyester granules suitable for immunoglobulin g purification. | the immunoglobulin g (igg) binding zz domain of protein a from staphylococcus aureus was fused to the n terminus of the polyhydroxyalkanoate (pha) synthase from cupriavidus necator. the fusion protein was confirmed by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry and mediated formation of zz domain-displaying pha granules in recombinant escherichia coli. the igg binding capacity of isolated granules was assessed using enzyme-linked immunosorbent assay and could be ... | 2006 | 16936052 |
| assay of poly(3-hydroxybutyrate) depolymerase activity and product determination. | two methods for accurate poly(3-hydroxybutyrate) (phb) depolymerase activity determination and quantitative and qualitative hydrolysis product determination are described. the first method is based on online determination of naoh consumption rates necessary to neutralize 3-hydroxybutyric acid (3hb) and/or 3hb oligomers produced during the hydrolysis reaction and requires a ph-stat apparatus equipped with a software-controlled microliter pump for rapid and accurate titration. the method is univer ... | 2006 | 16957234 |
| seleno-l-methionine is the predominant organic form of selenium in cupriavidus metallidurans ch34 exposed to selenite or selenate. | the accumulated organic form of selenium previously detected by x-ray absorption near-edge structure (xanes) analyses in cupriavidus metallidurans ch34 exposed to selenite or selenate was identified as seleno-l-methionine by coupling high-performance liquid chromatography to inductively coupled plasma-mass spectrometry. | 2006 | 16957274 |
| physiological-biochemical properties and the ability to synthesize polyhydroxyalkanoates of the glucose-utilizing strain of the hydrogen bacterium ralstonia eutropha b8562. | physiological-biochemical, genetic, and cultural properties of the glucose-utilizing mutant strain ralstonia eutropha b8562 have been compared with those of its parent strain r. eutropha b5786. it has been shown that growth characteristics of the strain cultured on glucose as the sole carbon and energy source are comparable with those of the parent strain. strain b8562 is characterized by high polyhydroxyalkanoate (pha) yields on different carbon sources (co(2), fructose, and glucose). pha accum ... | 2006 | 16960738 |
| genome sequence of the bioplastic-producing "knallgas" bacterium ralstonia eutropha h16. | the h(2)-oxidizing lithoautotrophic bacterium ralstonia eutropha h16 is a metabolically versatile organism capable of subsisting, in the absence of organic growth substrates, on h(2) and co(2) as its sole sources of energy and carbon. r. eutropha h16 first attracted biotechnological interest nearly 50 years ago with the realization that the organism's ability to produce and store large amounts of poly[r-(-)-3-hydroxybutyrate] and other polyesters could be harnessed to make biodegradable plastics ... | 2006 | 16964242 |
| increased abundance of incp-1beta plasmids and mercury resistance genes in mercury-polluted river sediments: first discovery of incp-1beta plasmids with a complex mer transposon as the sole accessory element. | although it is generally assumed that mobile genetic elements facilitate the adaptation of microbial communities to environmental stresses, environmental data supporting this assumption are rare. in this study, river sediment samples taken from two mercury-polluted (a and b) and two nonpolluted or less-polluted (c and d) areas of the river nura (kazakhstan) were analyzed by pcr for the presence and abundance of mercury resistance genes and of broad-host-range plasmids. pcr-based detection reveal ... | 2006 | 16980416 |
| molecular and population analyses of a recombination event in the catabolic plasmid pjp4. | cupriavidus necator jmp134(pjp4) harbors a catabolic plasmid, pjp4, which confers the ability to grow on chloroaromatic compounds. repeated growth on 3-chlorobenzoate (3-cb) results in selection of a recombinant strain, which degrades 3-cb better but no longer grows on 2,4-dichlorophenoxyacetate (2,4-d). we have previously proposed that this phenotype is due to a double homologous recombination event between inverted repeats of the multicopies of this plasmid within the cell. one recombinant for ... | 2006 | 16980481 |
| bias from h2 cleavage to production and coordination changes at the ni-fe active site in the nad+-reducing hydrogenase from ralstonia eutropha. | the soluble nad+-reducing ni-fe hydrogenase (sh) from ralstonia eutropha h16 is remarkable because it cleaves hydrogen in the presence of dioxygen at a unique ni-fe active site (burgdorf et al. (2005) j. am. chem. soc. 127, 576). by x-ray absorption (xas), ftir, and epr spectroscopy, we monitored the structure and oxidation state of its metal centers during h2 turnover. in nadh-activated protein, a change occurred from the (cn)o2ni(ii)(mu-s)2fe(ii)(cn)3(co) site dominant in the wild-type sh to a ... | 2006 | 16981725 |
| effects of ph of fermentation medium on biosynthesis of poly[(3-hydroxybutyrate)-co-(3-mercaptopropionate)] by wautersia eutropha. | a series of p(3hb-co-3mp)s with different 3mp unit content was biosynthesized by the fermentation of w. eutropha in a medium containing sodium gluconate and dtdp as carbon sources at different ph conditions ranging from ph 6.0 to 8.0. the p(3hb-co-3mp) samples were fractioned using the solvent/nonsolvent mixed solvent chloroform/heptane and the comonomer unit composition was investigated. it was found that w. eutropha produces p(3hb-co-3mp)s with extremely different 3mp unit content ranging from ... | 2006 | 17022093 |
| deciphering bioplastic production. | | 2006 | 17033660 |
| role of eukaryotic microbiota in soil survival and catabolic performance of the 2,4-d herbicide degrading bacteria cupriavidus necator jmp134. | cupriavidus necator (formerly ralstonia eutropha) jmp134, harbouring the catabolic plasmid pjp4, is the best-studied 2,4-dichlorophenoxyacetic acid (2,4-d) herbicide degrading bacterium. a study of the survival and catabolic performance of strain jmp134 in agricultural soil microcosms exposed to high levels of 2,4-d was carried out. when c. necator jmp134 was introduced into soil microcosms, the rate of 2,4-d removal increased only slightly. this correlated with the poor survival of the strain, ... | 2007 | 17043913 |
| production system for biodegradable polyester polyhydroxybutyrate by corynebacterium glutamicum. | a biosynthetic pathway for poly(3-hydroxybutyrate) [p(3hb)] production by corynebacterium glutamicum was developed by introducing the phbcab operon derived from ralstonia eutropha. p(3hb) synthase activity was detected in this recombinant c. glutamicum carrying a cell surface protein gene promoter. intracellular p(3hb) was microscopically observed as inclusion granules and its content was calculated to be 22.5% (w/w) with a number average molecular weight of 2.1x10(5) and a polydispersity of 1.6 ... | 2006 | 17046539 |
| modulation of tala gene in pentose phosphate pathway for overproduction of poly-beta-hydroxybutyrate in transformant escherichia coli harboring phbcab operon. | the tala gene encoding transaldolase, the key enzyme in the nonoxidative pentose phosphate pathway, was amplified in a transformant escherichia coli harboring the phbcab operon to shift the metabolic flux of the hexose mono-phosphate shunt to the odd-ball biosynthesis pathway for poly-beta-hydroxybutyrate overproduction. the phb content in the transformant e. coli coharboring the phbcab operon and tala gene increased from 28.2% to 52.3%, and the retarded cell growth was overcome. this increase s ... | 2006 | 17046540 |
| [evolution and phylogeny of rhizobia]. | nitrogen fixation an ancient process that may is have originated in the archaean eon under the primitive atmosphere anoxygenic conditions. diazotrophy is an exclusive process of prokaryotes, only euryarchaeota and 6 of 54 bacteria phyla have diazotrophs lineages. some of them coevolved with flowering plants for the establishment of molecular bases of a mutualistic symbiosis relationship. in rhizobia, the nitrogen fixation occurs inside the nodules, special structures on the roots or stems of leg ... | 2005 | 17061545 |
| escherichia coli o157:h7 survival and growth on lettuce is altered by the presence of epiphytic bacteria. | escherichia coli o157:h7 can survive in low numbers in soil and on plants. occasionally, conditions may occur in the field that lead to contamination of produce. survival of enteric pathogens in the field is controlled to a certain extent by complex interactions with indigenous soilborne and seedborne epiphytes. identifying these interactions may assist in developing strategies to improve produce safety. two epiphytes were isolated from pathogen-contaminated plants that interact differently with ... | 2006 | 17066909 |
| substrate consumption and biomass growth of ralstonia eutropha at various s0/x0 levels in batch cultures. | the biomass growth, substrate consumption and polyhydrobutyrate (phb) production of ralstonia eutropha with butyric acid and fructose as the carbon and energy sources at various ratios of initial substrate concentration (s0) to initial biomass concentration (x0) were investigated in this study. results indicated that the phb content increased with the increasing s0/x0 ratio. different substrates exhibited a similar trend for cell growth and substrates consumption with the changing s0/x0 ratio. t ... | 2007 | 17071078 |
| the ralstonia eutropha h16 phasin phap1 is targeted to intracellular triacylglycerol inclusions in rhodococcus opacus pd630 and mycobacterium smegmatis mc2155, and provides an anchor to target other proteins. | in ralstonia eutropha, the h16 phasin phap1 represents the major phasin that binds to the surface of polyhydroxyalkanoate (pha) inclusions. in this study, c-terminal fusions of phap1 with enhanced green fluorescent protein (egfp) and with escherichia coli beta-galactosidase (lacz) were expressed separately in the triacylglycerol (tag)-accumulating actinomycetes rhodococcus opacus pd630 and mycobacterium smegmatis mc(2)155, employing the m. smegmatis acetamidase (ace) promoter of the escherichia- ... | 2006 | 17074898 |
| maturation of hydrogenases. | enzymes possessing the capacity to oxidize molecular hydrogen have developed convergently three class of enzymes leading to: [fefe]-, [nife]-, and [fes]-cluster-free hydrogenases. they differ in the composition and the structure of the active site metal centre and the sequence of the constituent structural polypeptides but they show one unifying feature, namely the existence of cn and/or co ligands at the active site fe. recent developments in the analysis of the maturation of [fefe]- and [nife] ... | 2006 | 17091562 |
| a cytomic approach reveals population heterogeneity of cupriavidus necator in response to harmful phenol concentrations. | the understanding of functions of cells within microbial populations or communities is certainly needed for existing and novel cytomic approaches which grip the individual scale. population behaviour results from single cell performances and is caused by the individual genetic pool, history, life cycle states and microenvironmental surroundings. mimicking natural impaired environments, the paper shows that the gram-negative betaproteobacterium cupriavidus necator dramatically altered its populat ... | 2006 | 17106909 |
| burkholderia phymatum is a highly effective nitrogen-fixing symbiont of mimosa spp. and fixes nitrogen ex planta. | * the ability of burkholderia phymatum stm815 to effectively nodulate mimosa spp., and to fix nitrogen ex planta, was compared with that of the known mimosa symbiont cupriavidus taiwanensis lmg19424. * both strains were equally effective symbionts of m. pudica, but nodules formed by stm815 had greater nitrogenase activity. stm815 was shown to have a broader host range across the genus mimosa than lmg19424, nodulating 30 out of 31 species, 21 of these effectively. lmg19424 effectively nodulated o ... | 2007 | 17176403 |
| growth of the genetically engineered strain cupriavidus necator rw112 with chlorobenzoates and technical chlorobiphenyls. | cupriavidus necator (formerly ralstonia eutropha) strain h850 is known to grow on biphenyl, and to co-oxidize congeners of polychlorinated biphenyls (pcbs). using a tn5-based minitransposon shuttle system and the tol plasmid, the rational construction of hybrids of h850 was achieved by subsequent introduction of three distinct elements carrying 11 catabolic loci from three other biodegrading bacteria into the parent strain, finally yielding c. necator rw112. the new genetic elements introduced i ... | 2007 | 17185547 |
| diversity of the abundant pklc102/pagi-2 family of genomic islands in pseudomonas aeruginosa. | the known genomic islands of pseudomonas aeruginosa clone c strains are integrated into trna(lys) (pklc102) or trna(gly) (pagi-2 and pagi-3) genes and differ from their core genomes by distinctive tetranucleotide usage patterns. pklc102 and the related island papi-1 from p. aeruginosa pa14 were spontaneously mobilized from their host chromosomes at frequencies of 10% and 0.3%, making pklc102 the most mobile genomic island known with a copy number of 30 episomal circular pklc102 molecules per cel ... | 2007 | 17194795 |
| characterization and application of a rolling-circle-type plasmid from cupriavidus taiwanensis. | two small cryptic plasmids, ptj86-1 and ptj86-2, identified in cupriavidus taiwanensis strain tj86, were detected and characterized. complete sequencing of ptj86-1 and ptj86-2 revealed these plasmids to be 2221 and 2229bp in length with a gc content of 61.7% and 61.6%, respectively. both plasmids harbored four open reading frames (orf1, 2, 3 and 4). only the predicted orf1 gene product of both plasmids (436 amino acids) was homologous to rep proteins previously identified on plasmids replicated ... | 2007 | 17196653 |
| desulfurization of aromatic sulfonates by rhizosphere bacteria: high diversity of the asfa gene. | the plant growth-promoting effect of pseudomonas putida s-313 is associated with its ability to desulfurize arylsulfonates. to understand this further, other plant-associated bacteria able to desulfurize a range of arylsulfonates were isolated from the rhizospheres of winter and spring barley. the isolates belonged to the beta-proteobacteria, including bacteria from the variovorax paradoxus group and from the acidovorax genus. they desulfurized toluenesulfonate to p-cresol, and were found to con ... | 2007 | 17222151 |
| impact of alterations near the [nife] active site on the function of the h(2) sensor from ralstonia eutropha. | in proteobacteria capable of h(2) oxidation under (micro)aerobic conditions, hydrogenase gene expression is often controlled in response to the availability of h(2). the h(2)-sensing signal transduction pathway consists of a heterodimeric regulatory [nife]-hydrogenase (rh), a histidine protein kinase and a response regulator. to gain insights into the signal transmission from the ni-fe active site in the rh to the histidine protein kinase, conserved amino acid residues in the l0 motif near the a ... | 2007 | 17222178 |
| heat-shock protein hspa mimics the function of phasins sensu stricto in recombinant strains of escherichia coli accumulating polythioesters or polyhydroxyalkanoates. | polyhydroxyalkanoic acids (phas) are synthesized by unspecific pha synthases and deposited as energy and carbon storage granules in the cytoplasm of many prokaryotes. the number and size of the granules depend on the presence of phasins which are amphiphilic structural proteins occurring at the granule surface. recently, it was shown that polythioesters (ptes) are also synthesized by pha synthases. to increase the yield of these polymers, the role of recombinant phasins was analysed in an artifi ... | 2007 | 17259608 |
| sequencing microbial copolymers of 3-hydroxybutyric and 3-mercaptoalkanoic acids by nmr, electrospray ionization mass spectrometry, and size exclusion chromatography nmr. | copolymers of 3-hydroxybutyrate (3hb) and 3-mercaptopropionate (3mp) or 3-mercaptobutyrate (3mb) units and minor amounts of 3-hydroxypropionate (3hp), 3-hydroxyvalerate (3hv), or 3-mercaptovalerate (3mv) were investigated regarding their microstructure by nmr, electrospray ionization mass spectrometry, and size exclusion chromatography nmr. these copolymers were produced by ralstonia eutropha strain h16 when cells were cultivated in a mineral salts medium with gluconate as a carbon source for gr ... | 2007 | 17261066 |
| production of poly(3-hydroxybutyric-co-3-hydroxyvaleric acid) having a high hydroxyvalerate content with valeric acid feeding. | the capability of different organic acids to produce a derivative of phb [poly(3-hydroxybutyric-co-3-hydroxyvaleric acid), p(3hb-co-3hv)] was examined in shake flask cultivations. propionic and valeric acids demonstrated the potential to produce p(3hb-co-3hv) under nitrogen limiting conditions at 30 degrees c. the addition time and the initial concentration of valeric acid needed for a high cellular hv content were identified by extensive experimentation. fed-batch cultivation in 7-l bioreactor ... | 2007 | 17268758 |
| fermentative production of (r)-(-)-3-hydroxybutyrate using 3-hydroxybutyrate dehydrogenase null mutant of ralstonia eutropha and recombinant escherichia coli. | two systems, one using an (r)-(-)-3-hydroxybutyrate dehydrogenase (bdh) null mutant of ralstonia eutropha and the other using a recombinant escherichia coli strain containing a synthetic poly[(r)-(-)-3-hydroxybutyrate] (phb) operon and an extracellular phb depolymerase gene, were used for the fermentative production of (r)-(-)-3-hydroxybutyrate (3hb). the concentration of 3hb in the culture supernatant of the mutant r. eutropha system reached about 30 mm after 5 d under anaerobic conditions, alt ... | 2006 | 17270718 |
| characterization of the signaling domain of the no-responsive regulator norr from ralstonia eutropha h16 by site-directed mutagenesis. | in ralstonia eutropha h16, the nitric oxide (no)-responsive transcriptional activator norr controls the expression of a dicistronic operon that encodes a membrane-bound no reductase, norb, and a protein of unknown function, nora. the n-terminal domain (ntd) of norr is responsible for perception of the signal molecule, nitric oxide. thirteen out of 29 conserved residues of the ntd were exchanged by site-directed mutagenesis. replacement of r63, r72, d93, d96, c112, d130, or f137 strongly decrease ... | 2007 | 17277050 |
| studies on the influence of phasins on accumulation and degradation of phb and nanostructure of phb granules in ralstonia eutropha h16. | phasins play an important role in the formation of poly(3-hydroxybutyrate) [phb] granules and affect their size and number in the cells. recent studies on the phb granule proteome and analysis of the complete genomic dna sequence of ralstonia eutropha h16 have identified three homologues of the phasin protein phap1. in this study, mutants of r. eutropha deficient in the expression of the phasin genes phap1, phap2, phap3, phap4, phap12, phap123, and phap1234 were examined by gas chromatography. i ... | 2007 | 17291089 |
| poly[(r)-3-hydroxybutyrate] formation in escherichia coli from glucose through an enoyl-coa hydratase-mediated pathway. | in this study, a new metabolic pathway for the synthesis of poly[(r)-3-hydroxybutyrate] [p(3hb)] was constructed in a recombinant escherichia coli strain that utilized forward and reverse reactions catalyzed by two substrate-specific enoyl-coa hydratases, r-hydratase (phaj) and s-hydratase (fadb), to epimerize (s)-3hb-coa to (r)-3hb-coa via a crotonyl-coa intermediate. the r-hydratase gene (phaj(ac)) from aeromonas caviae was coexpressed with the pha synthase gene (phac(re)) and 3-ketothiolase g ... | 2007 | 17298899 |
| biosynthesis of polyhydroxybutyrate (phb) and extracellular polymeric substances (eps) by ralstonia eutropha atcc 17699 in batch cultures. | the production of polyhydroxybutyrate (phb) and extracellular polymeric substances (eps) by ralstonia eutropha atcc 17699 at various glucose and (nh4)2so4 concentrations in batch cultures were investigated. the biosynthesis of eps by r. eutropha closely coupled with cell growth, while phb was synthesized only under nitrogen-deficient and cell-growth-limited conditions. experimental results show that the specific phb production rate had an exponential correlation with both specific cell growth ra ... | 2007 | 17318537 |
| genetic characterization of 2,4,6-trichlorophenol degradation in cupriavidus necator jmp134. | the degradation pathway of 2,4,6-trichlorophenol (2,4,6-tcp), a hazardous pollutant, in the aerobic bacterium cupriavidus necator jmp134(pjp4) (formerly ralstonia eutropha jmp134) is encoded by the tcp genes. these genes are located in a genetic context, tcprxabcyd, which resembles a putative catabolic operon. in this work, these gene sequences were individually disrupted and mutant strains were evaluated for their ability to grow on or degrade 2,4,6-tcp. the tcpx and tcpa mutants completely fai ... | 2007 | 17322325 |
| methods for extracting biochemical information from bacterial raman spectra: an explorative study on cupriavidus metallidurans. | in this study, we explore raman spectra of bacteria for their biochemical information. therefore, a database of biomolecules was used and several approaches were applied such as the study of difference spectra, the calculation dot products, the usage of coefficients obtained from an emsc procedure and the application of 2d correlation spectroscopy. these methods were applied on a dataset containing raman spectra of cupriavidus metallidurans lmg 1195 in five stages of its growth, aiming to extrac ... | 2007 | 17386670 |
| environmental analysis of plastic production processes: comparing petroleum-based polypropylene and polyethylene with biologically-based poly-beta-hydroxybutyric acid using life cycle analysis. | polymers based on olefins have wide commercial applicability. however, they are made from non-renewable resources and are characterised by difficulty in disposal where recycle and re-use is not feasible. poly-beta-hydroxybutyric acid (phb) provides one example of a polymer made from renewable resources. before motivating its widespread use, the advantages of a renewable polymer must be weighed against the environmental aspects of its production. previous studies relating the environmental impact ... | 2007 | 17400318 |
| the inherent property of polyhydroxyalkanoate synthase to form spherical pha granules at the cell poles: the core region is required for polar localization. | only the pha synthase is required for formation of spherical intracellular pha granules emerging at cell poles. this study aims to assign the polar targeting signal in the pha synthase and to provide insight into molecular mechanisms of granule formation. random in-frame insertion mutagenesis indicated dispensable and essential regions suggesting that only the n terminus (<100 aa) is dispensable and forms a random coil structure. the inactive pha synthase (c319a) is still localized to cell poles ... | 2007 | 17420063 |
| [study on the structure and function of a stable methane-oxidizing mixed microbial consortium]. | from an agricultural sample taken in chongqing, a stable methane-oxidizing mixed microbial consortium was established by enrichment culture with methane as a sole source of carbon and energy. the mixed consortium showed high capability of phenol degradation and 1,2-epoxypropane production from propene. more than 99% of phenol at an initial concentration of 600mg/l could be degraded by the mixed microbial consortium after 11 h of cultivation. the productivity of 1, 2-epoxypropane could be increas ... | 2007 | 17436634 |
| kinetic studies on autohydrogenotrophic growth of ralstonia eutropha with nitrate as terminal electron acceptor. | autohydrogenotrophic batch growth of ralstonia eutropha h16 was studied in a stirred-tank reactor with nitrate and nitrite as terminal electron acceptors and the sole limiting substrates. assuming product inhibition by nitrite, saturation kinetics with the two limiting substrates and a simple switching function, which allows growth on nitrite only at low nitrate concentrations, resulted in a kinetic growth model with nine model parameters. the data of two batch experiments were used to identify ... | 2007 | 17457540 |
| molecular detection and diversity of novel diterpenoid dioxygenase dita1 genes from proteobacterial strains and soil samples. | resin acids are tricyclic diterpenoids naturally synthesized by trees that are released from wood during pulping processes. using a newly designed primer set, genes similar to that encoding the dita1 catalytic alpha-subunit of the diterpenoid dioxygenase, a key enzyme in abietane resin acid degradation by pseudomonas abietaniphila bkme-9, could be amplified from different pseudomonas strains, whereas dita1 gene sequence types representing distinct branches in the evolutionary tree were amplified ... | 2007 | 17472635 |
| formation of a dinitrosyl iron complex by nora, a nitric oxide-binding di-iron protein from ralstonia eutropha h16. | in ralstonia eutropha h16, two genes, nora and norb, form a dicistronic operon that is controlled by the no-responsive transcriptional regulator norr. norb has been identified as a membrane-bound no reductase, but the physiological function of nora is unknown. we found that, in a nora deletion mutant, the promoter activity of the norab operon was increased 3-fold, indicating that nora attenuates activation of norr. nora shows limited sequence similarity to the oxygen carrier hemerythrin, which c ... | 2007 | 17507380 |
| monophyly of noda and nifh genes across texan and costa rican populations of cupriavidus nodule symbionts. | noda and nifh phylogenies for cupriavidus nodule bacteria from native legumes in texas and costa rica grouped all strains into a single clade nested among neotropical burkholderia strains. thus, cupriavidus symbiotic genes were not acquired independently in different regions and are derived from other betaproteobacteria rather than from alpha-rhizobial donors. | 2007 | 17526782 |
| fed-batch cultivation of wautersia eutropha. | batch kinetics of polyhydroxybutyrate (phb) synthesis in a bioreactor under controlled conditions of ph and dissolved oxygen gave a biomass of 14 g l(-1) with a phb concentration of 6.1 g l(-1) in 60 h. the data of the batch kinetics was used to develop a mathematical model, which was then extrapolated to fed-batch by incorporating the dilution due to substrate feeding. offline computer simulation of the fed-batch model was done to develop the nutrient feeding strategies in the fed-batch cultiva ... | 2008 | 17532211 |
| mechanical properties of comonomer-compositionally fractionated poly[(3-hydroxybutyrate)-co-(3-mercaptopropionate)] with low 3-mercaptopropionate unit content. | the mechanical properties, such as young's modulus, yield strength, and the elongation at breakage, were investigated for several sulfur-containing biopolymers p(3hb-co-3mp). a series of p(3hb-co-3mp) samples with 3mp unit content ranging from 6.6 to 39.1 mol-% was biosynthesized by fermentation using the pha-synthesizing bacteria cupriavidus necator. for comparison, the bacterially synthesized p(3hb) and p(3hb-co-3hp) with the 3hp unit content ranging from 13.1 to 21.1 mol-% were also investiga ... | 2007 | 17541927 |
| variation in copolymer composition and molecular weight of polyhydroxyalkanoate generated by saturation mutagenesis of aeromonas caviae pha synthase. | amino acid substitutions at two residues downstream from the active-site histidine of polyhydroxyalkanoate (pha) synthases are effective for changing the composition and the molecular weight of pha. in this study, saturation mutagenesis at the position ala505 was applied to pha synthase (phacac) from aeromonas caviae to investigate the effects on the composition and the molecular weight of pha synthesized in ralstonia eutropha. the copolymer composition and molecular weight of pha were varied by ... | 2007 | 17541931 |
| toward automated analysis of biofilm architecture: bias caused by extraneous confocal laser scanning microscopy images. | an increasing number of studies utilize confocal laser scanning microscopy (clsm) for in situ visualization of biofilms and rely on the use of image analysis programs to extract quantitative descriptors of architecture. recently, designed programs have begun incorporating procedures to automatically determine threshold values for three-dimensional clsm image stacks. we have found that the automated threshold calculation is biased when a stack contains images lacking pixels of biological signific ... | 2007 | 17545329 |
| heterodimeric nitrate reductase (napab) from cupriavidus necator h16: purification, crystallization and preliminary x-ray analysis. | the periplasmic nitrate reductase from cupriavidus necator (also known as ralstonia eutropha) is a heterodimer that is able to reduce nitrate to nitrite. it comprises a 91 kda catalytic subunit (napa) and a 17 kda subunit (napb) that is involved in electron transfer. the larger subunit contains a molybdenum active site with a bis-molybdopterin guanine dinucleotide cofactor as well as one [4fe-4s] cluster, while the small subunit is a di-haem c-type cytochrome. crystals of the oxidized form of th ... | 2007 | 17554176 |
| contribution of extracytoplasmic function sigma factors to transition metal homeostasis in cupriavidus metallidurans strain ch34. | cupriavidus metallidurans strain ch34 is a highly metal-resistant bacterium that contains 11 sigma factors of the extracytoplasmic function (ecf) protein family, which can be subgrouped into the ecf:feci 1, ecf:feci 2, ecf:rpoe and '(ecf)' clusters. to analyze the contribution of these 11 sigma factors to metal resistance, upregulation of the respective genes was measured by quantitative real-time reverse transcriptase polymerase chain reaction (qrt-pcr). as determined by rt-pcr, the ecf sigma f ... | 2007 | 17587871 |