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Clinton R Fuller - One of the best experts on this subject based on the ideXlab platform.
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bacterial production of polyesters from free fatty acids obtained from natural oils by Pseudomonas oleovorans
Journal of Environmental Polymer Degradation, 1998Co-Authors: Baki Hazer, Robert W. Lenz, Clinton R Fuller, Oktay Torul, Mehlika Borcakli, Steven D GoodwinAbstract:The carboxylic acids derived from olive oil, hazelnut oil, sesame oil and hamci(anchovy) oil were evaluated as substrates for cell growth and the production of reserve polyesters by Pseudomonas oleovorans. Poly-3-hydroxy alkanoates containing both saturated(mainly 3-hydroxy-octanoate and 3-hydroxy-decanoate) and unsaturated repeating units with 8 to 20 carbon atoms, or more, were produced in 26 to 61% yields based on cell dry weights. The number average molecular weights of these polymers varied from 45,000 to 68,000 Daltons.
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poly 3 hydroxyalkanoate s produced by Pseudomonas oleovorans grown by feeding nonanoic and 10 undecenoic acids in sequence
Polymer Journal, 1997Co-Authors: Young Ha Rhee, Robert W. Lenz, Clinton R FullerAbstract:Poly(3-hydroxyalkanoate)s Produced by Pseudomonas oleovorans Grown by Feeding Nonanoic and 10-Undecenoic Acids in Sequence
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sequential production of two different polyesters in the inclusion bodies of Pseudomonas oleovorans
International Journal of Biological Macromolecules, 1996Co-Authors: Joanne M Curley, Robert W. Lenz, Clinton R FullerAbstract:Abstract When Pseudomonas oleovorans was grown on a mixture of 5-phenylvaleric acid, PVA, and nonanoic acid, NA, the reserve polyester produced included both a homopolymer and a copolymer. The homopolymer poly-3-hydroxy-5-phenylvalerate, PHPV, contained only 3-hydroxy-5-phenylvalerate units, while the copolymer contained the same long chain 3-hydroxyalkanoates as those present in the copolymer poly-3-hydroxynonanoate, PHN, which is produced from nonanoic acid alone. The intracellular location of each of these polymers was determined by selective staining of the inclusion body granules with ruthenium tetraoxide and examination by transmission electron microscopy showed that both types of polyesters occurred in the same granule. PHN was present in the center of the granule, while PHPV accumulated around the PHN in the inclusion body. The proteins associated with the inclusion bodies were separated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). In all cases, two different polymerase enzymes of molecular weight 59 and 55 KDa were present, indicating that the same polymerase enzyme system was responsible for the production of both PHN and PHPV. Attempts were made to produce a random copolymer containing both alkyl and phenylalkyl repeat units by varying the growth conditions, but a mixture of PHN and PHPV was always produced instead
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production of poly 3 hydroxyalkanoates containing aromatic substituents by Pseudomonas oleovorans
Macromolecules, 1996Co-Authors: Joanne M Curley, Robert W. Lenz, And Baki Hazer, Clinton R FullerAbstract:Pseudomonas oleovorans was grown separately on 5-(4'-tolyl)valeric acid, 5-(4'-ethylphenyl)-valeric acid, 5-(4'-biphenyl)valeric acid, and 8-(4'-tolyl)octanoic acid either as the sole carbon source or as a coefeed with either nonanoic acid or 5-phenylvaleric acid. For polymer production, 5-(4'-tolyl)valeric acid was the most effective growth substrate of the five. It resulted in the production of poly-3-hydroxy-5-(4'-tolyl)valerate, a crystalline polymer with a glass transition temperature of 18 °C and a melting transition of 95 °C. This poly(3-hydroxyalkanoate) (PHA) is apparently the first example of a crystalline aromatic-containing bacterial PHA. When P. oleovorans was cofed an equimolar mixture of 5-phenylvaleric acid and 5-(4'-tolyl)valeric acid, the polymer produced contained 36 mol % of 3-hydroxy-5-phenylvalerate and 64 mol % of 3-hydroxy-5-(4'-tolyl)valerate, and it did not crystallize.
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quantitative determination of intracellular depolymerase activity in Pseudomonas oleovorans inclusions containing poly 3 hydroxyalkanoates with long alkyl substituents
Fems Microbiology Letters, 1994Co-Authors: John L R Foster, Robert W. Lenz, Clinton R FullerAbstract:Research regarding the accurate, quantitative degradation of novel poly-3-hydroxyalkanoates has been restricted by the absence of an appropriate monitoring technique. The calibration of a gas chromatograph to poly-3-hydroxyalkanoate reveals a linear relationship between the area under gas chromatograph tracings and polymer weight. With this new method, poly-3-hydroxyactanoate granules isolated from Pseudomonas oleovorans, which were incubated at 30°C in an alkaline buffer, exhibited a linear degradation rate. Degradation was inhibited by the presence of Triton X-100 and phenylmethylsulfonyl fluoride. The depolymerase was demonstrated to be associated with the polymer granule complex and most likely possessed serine residues at its active site.
Robert W. Lenz - One of the best experts on this subject based on the ideXlab platform.
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Production of a chiral polyester by Pseudomonas oleovorans grown with 5‐phenyl‐2,4‐pentadienoic acid
Chirality, 2004Co-Authors: Safwat Antoun, Robert W. Lenz, Ilaria Grizzi, R. Clinton FullerAbstract:Pseudomonas oleovorans has been previously shown to produce a polyester containing a phenyl pendant group when grown with 5-phenylpentanoic acid under nutrient-limiting conditions. The same polyester was produced when 5-phenyl-2,4-pentadienoic acid was the only carbon source, and a mixture of two different polymers was produced when this bacterium was grown on a mixture of 5-phenyl-2,4-pentadienoic acid and nonanoic acid. The polymer blend obtained was separated by fractional crystallization to yield poly(3-hydroxy-5-phenylpentanoate) and the copolymer which is normally produced with nonanoic acid alone.
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compositional limitations in poly 3 hydroxyalkanoates produced by Pseudomonas oleovorans
Journal of Environmental Polymer Degradation, 1998Co-Authors: E. S. Stuart, Robert W. Lenz, R. C. FullerAbstract:It is well known that Pseudomonas oleovorans can utilize sodium octanoate for both cell growth and the synthesis of polyhydroxyalkanoates (PHAs), but it can utilize sodium butyrate only for limited cell growth and not for the polyester formation when this substrate is the sole carbon source. Therefore, these two substrates were evaluated as cofeeds for the possible incorporation of 3-hydroxybutyryl groups in the resulting PHA. When sodium butyrate and sodium octanoate were fed to P. oleovorans as cosubstrates in various proportions, the resultant cell density and polymer content were proportional to the amount of sodium octanoate in the feed. The PHA extracted from cells grown in all combinations of these cosubstrates had similar unit compositions of approximately 8 mole % 3-hydroxyhexanoate, 91 mole % 3-hydroxyoctanoate and 1 mole % 3-hydroxydecanoate. 3-Hydroxybutyrate units were not detected in any of the PHAs isolated, indicating that these units could not be incorporated in the copolymer synthesized by P. oleovorans either because the cell did not synthesize that monomer or, if it did, the PHA synthase could not copolymerize it with the longer chain monomers.
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bacterial production of polyesters from free fatty acids obtained from natural oils by Pseudomonas oleovorans
Journal of Environmental Polymer Degradation, 1998Co-Authors: Baki Hazer, Robert W. Lenz, Clinton R Fuller, Oktay Torul, Mehlika Borcakli, Steven D GoodwinAbstract:The carboxylic acids derived from olive oil, hazelnut oil, sesame oil and hamci(anchovy) oil were evaluated as substrates for cell growth and the production of reserve polyesters by Pseudomonas oleovorans. Poly-3-hydroxy alkanoates containing both saturated(mainly 3-hydroxy-octanoate and 3-hydroxy-decanoate) and unsaturated repeating units with 8 to 20 carbon atoms, or more, were produced in 26 to 61% yields based on cell dry weights. The number average molecular weights of these polymers varied from 45,000 to 68,000 Daltons.
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poly 3 hydroxyalkanoate s produced by Pseudomonas oleovorans grown by feeding nonanoic and 10 undecenoic acids in sequence
Polymer Journal, 1997Co-Authors: Young Ha Rhee, Robert W. Lenz, Clinton R FullerAbstract:Poly(3-hydroxyalkanoate)s Produced by Pseudomonas oleovorans Grown by Feeding Nonanoic and 10-Undecenoic Acids in Sequence
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intracellular depolymerase functionality and location in Pseudomonas oleovorans inclusions containing polyhydroxyoctanoate
International Journal of Biological Macromolecules, 1996Co-Authors: E. S. Stuart, Robert W. Lenz, L J R Foster, R. C. FullerAbstract:Abstract Microbial poly-3-hydroxyoctanoate inclusion bodies produced by Pseudomonas oleovorans when grown on n -octanoic acid, are complex macromolecular structures consisting of polyester, organized paracrystalline lattice arrays and lipids. While it is known that the polymer in the granules maintains its native, amorphous state while it is surrounded by the components of this complex, the precise functions of the various components during polymer production and utilization have yet to be established. By utilizing electron microscopy, SDS-PAGE, and gel filtration chromatography along with in vitro assays for depolymerase activity, the present study demonstrates that a protein species with molecular weight of ∼ 32 kDa is the depolymerase protein of the polymer inclusion. When exogenous carbon was exhausted, cell viability required utilization of the stored polyester. Under these conditions, the concentration of the depolymerase increased while the concentrations of the polymerase decreased. Thus, the association of the depolymerase with the granules was shown to be under metabolic regulation relative to the polymerase. The results from the present studies show that careful manipulation of the substrate concentration can selectively, and differentially, alter the level of inclusion associated proteins as well as the quantity and quality of the polyester which is accumulated.
Bernard Witholt - One of the best experts on this subject based on the ideXlab platform.
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evidence of medium chain length polyhydroxyoctanoate accumulation in transgenic potato lines expressing the Pseudomonas oleovorans pha c1 polymerase in the cytoplasm
Biochemical Engineering Journal, 2003Co-Authors: Andrea Romano, Gerrit Eggink, Bernard Witholt, Dick Vreugdenhil, Diaan C L Jamar, Linus H W Van Der Plas, Hans MooibroekAbstract:The phaC1 gene from Pseudomonas oleovorans, coding for the Pha-C1 polymerase, was introduced into the potato genome. Transgenic callus and plant lines which transcribed and translated the transgene were selected and cell suspension cultures from the wild type and transgenic lines were established. The substrate for the Pha-C1 polymerase, 3-(R)-hydroxyoctanoate, was provided to the growth medium. In the transgenic lines, but not in the wild type or in transgenic cell suspension cultures without Pha-C1 expression, evidence of medium-chain-length polyhydroxyalkanoate accumulation ranging from 0.02 to 9.7 mg of polymer per gram of dry weight was observed after feeding in the growth medium the substrate.
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role of phad in accumulation of medium chain length poly 3 hydroxyalkanoates in Pseudomonas oleovorans
Applied and Environmental Microbiology, 2000Co-Authors: Stefan Klinke, Bernard Witholt, Birgit KesslerAbstract:Pseudomonas oleovorans is capable of producing poly(3-hydroxyalkanoates) (PHAs) as intracellular storage material. To analyze the possible involvement of phaD in medium-chain-length (MCL) PHA biosynthesis, we generated a phaD knockout mutant by homologous recombination. Upon disruption of the phaD gene, MCL PHA polymer accumulation was decreased. The PHA granule size was reduced, and the number of granules inside the cell was increased. Furthermore, mutant cells appeared to be smaller than wild-type cells. Investigation of MCL PHA granules revealed that the pattern of granule-associated proteins was changed and that the predominant protein PhaI was missing in the mutant. Complementation of the mutant with a phaD-harboring plasmid partially restored the wild-type characteristics of MCL PHA production and fully restored the granule and cell sizes. Furthermore, PhaI was attached to the granules of the complemented mutant. These results indicate that the phaD gene encodes a protein which plays an important role in MCL PHA biosynthesis. However, although its main effect seems to be the stabilization of MCL PHA granules, we found that the PhaD protein is not a major granule-associated protein and therefore might act by an unknown mechanism involving the PhaI protein.
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Expression, stability and performance of the three‐component alkane mono‐oxygenase of Pseudomonas oleovorans in Escherichia coli
FEBS Journal, 2000Co-Authors: Ivo E Staijen, Jan B Van Beilen, Bernard WitholtAbstract:We tested the synthesis and in vivo function of the inducible alkane hydroxylase of Pseudomonas oleovorans GPo1 in several Escherichia coli recombinants. The enzyme components (AlkB, AlkG and AlkT) were synthesized at various rates in different E. coli hosts, which after induction produced between twofold and tenfold more of the Alk components than did P. oleovorans. The enzyme components were less stable in recombinant E. coli hosts than in P. oleovorans. In addition, the specific activity of the alkane mono-oxygenase component AlkB was five or six times lower in E. coli than in P. oleovorans. Evidently, optimal functioning of the hydroxylase system requires factors or a molecular environment that are available in Pseudomonas but not in E. coli. These factors are likely to include correct interactions of AlkB with the membrane and incorporation of iron into the AlkG and AlkB apoproteins.
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expression stability and performance of the three component alkane mono oxygenase of Pseudomonas oleovorans in escherichia coli
FEBS Journal, 2000Co-Authors: Ivo E Staijen, Jan B Van Beilen, Bernard WitholtAbstract:We tested the synthesis and in vivo function of the inducible alkane hydroxylase of Pseudomonas oleovorans GPo1 in several Escherichia coli recombinants. The enzyme components (AlkB, AlkG and AlkT) were synthesized at various rates in different E. coli hosts, which after induction produced between twofold and tenfold more of the Alk components than did P. oleovorans. The enzyme components were less stable in recombinant E. coli hosts than in P. oleovorans. In addition, the specific activity of the alkane mono-oxygenase component AlkB was five or six times lower in E. coli than in P. oleovorans. Evidently, optimal functioning of the hydroxylase system requires factors or a molecular environment that are available in Pseudomonas but not in E. coli. These factors are likely to include correct interactions of AlkB with the membrane and incorporation of iron into the AlkG and AlkB apoproteins.
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isolation and characterization of the cis trans unsaturated fatty acid isomerase of Pseudomonas oleovorans gpo12
Journal of Bacteriology, 1999Co-Authors: Valerian Pedrotta, Bernard WitholtAbstract:Pseudomonas oleovorans contains an isomerase which catalyzes the cis-trans conversion of the abundant unsaturated membrane fatty acids 9-cis-hexadecenoic acid (palmitoleic acid) and 11-cis-octadecenoic acid (vaccenic acid). We purified the isomerase from the periplasmic fraction of Pseudomonas oleovorans. The molecular mass of the enzyme was estimated to be 80 kDa under denaturing conditions and 70 kDa under native conditions, suggesting a monomeric structure of the active enzyme. N-terminal sequencing showed that the isomerase derives from a precursor with a signal sequence which is cleaved from the primary translation product in accord with the periplasmic localization of the enzyme. The purified isomerase acted only on free unsaturated fatty acids and not on esterified fatty acids. In contrast to the in vivo cis-trans conversion of lipids, this in vitro isomerization of free fatty acids did not require the addition of organic solvents. Pure phospholipids, even in the presence of organic solvents, could not serve as substrate for the isomerase. However, when crude membranes from Pseudomonas or Escherichia coli cells were used as phospholipid sources, a cis-trans isomerization was detectable which occurred only in the presence of organic solvents. These results indicate that isolated membranes from Pseudomonas or E. coli cells must contain factors which, activated by the addition of organic solvents, enable and control the cis-trans conversion of unsaturated acyl chains of membrane phospholipids by the periplasmic isomerase.
R. C. Fuller - One of the best experts on this subject based on the ideXlab platform.
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compositional limitations in poly 3 hydroxyalkanoates produced by Pseudomonas oleovorans
Journal of Environmental Polymer Degradation, 1998Co-Authors: E. S. Stuart, Robert W. Lenz, R. C. FullerAbstract:It is well known that Pseudomonas oleovorans can utilize sodium octanoate for both cell growth and the synthesis of polyhydroxyalkanoates (PHAs), but it can utilize sodium butyrate only for limited cell growth and not for the polyester formation when this substrate is the sole carbon source. Therefore, these two substrates were evaluated as cofeeds for the possible incorporation of 3-hydroxybutyryl groups in the resulting PHA. When sodium butyrate and sodium octanoate were fed to P. oleovorans as cosubstrates in various proportions, the resultant cell density and polymer content were proportional to the amount of sodium octanoate in the feed. The PHA extracted from cells grown in all combinations of these cosubstrates had similar unit compositions of approximately 8 mole % 3-hydroxyhexanoate, 91 mole % 3-hydroxyoctanoate and 1 mole % 3-hydroxydecanoate. 3-Hydroxybutyrate units were not detected in any of the PHAs isolated, indicating that these units could not be incorporated in the copolymer synthesized by P. oleovorans either because the cell did not synthesize that monomer or, if it did, the PHA synthase could not copolymerize it with the longer chain monomers.
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Compositional Limitations in Poly–3–Hydroxyalkanoates Produced by Pseudomonas oleovorans
Journal of environmental polymer degradation, 1998Co-Authors: E. S. Stuart, R. W. Lenz, R. C. FullerAbstract:It is well known that Pseudomonas oleovorans can utilize sodium octanoate for both cell growth and the synthesis of polyhydroxyalkanoates (PHAs), but it can utilize sodium butyrate only for limited cell growth and not for the polyester formation when this substrate is the sole carbon source. Therefore, these two substrates were evaluated as cofeeds for the possible incorporation of 3-hydroxybutyryl groups in the resulting PHA. When sodium butyrate and sodium octanoate were fed to P. oleovorans as cosubstrates in various proportions, the resultant cell density and polymer content were proportional to the amount of sodium octanoate in the feed. The PHA extracted from cells grown in all combinations of these cosubstrates had similar unit compositions of approximately 8 mole % 3-hydroxyhexanoate, 91 mole % 3-hydroxyoctanoate and 1 mole % 3-hydroxydecanoate. 3-Hydroxybutyrate units were not detected in any of the PHAs isolated, indicating that these units could not be incorporated in the copolymer synthesized by P. oleovorans either because the cell did not synthesize that monomer or, if it did, the PHA synthase could not copolymerize it with the longer chain monomers.
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intracellular depolymerase and polyhydroxyoctanoate granule integrity in Pseudomonas oleovorans
International Journal of Biological Macromolecules, 1996Co-Authors: L J R Foster, Robert W. Lenz, E. S. Stuart, Ali Tehrani, R. C. FullerAbstract:Abstract When polyhydroxyoctanoate (PHO) was produced by Pseudomonas oleovorans during a regimen of intermittent feeding on octanoic acid, there was a significant change in both the polymer associated proteins and the composition of the enclosed polymer. The polymer granules were isolated with their protein coat intact and the enzymatic hydrolysis of the polymer within this cell free system was determined. The degradation rate for the PHO in these native granules reached a maximum of 1.17 mg/h at an optimum pH of 9 when incubated at 30°C. A study of the effect of various inhibitors on depolymerase activity suggested that the enzyme most likely has disulfide linkages and serine residues at its active site. Ultrastructure studies suggested this loss of enzyme activity was correlated with significant organizational degeneration in the proteins associated with the PHO inclusion body. Once solubilized from the granule, the depolymerase itself remained enzymatically active, and addition of this released material to other granule preparations increased the rate of polymer granule degradation. Similarly, when colloidal suspensions of purified, amorphous PHO were placed in contact with that depolymerase, they also underwent rapid degradation. In contrast, when crystalline solvent-cast PHO films were placed in contact with this enzyme, no degradative activity was observed.
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intracellular depolymerase functionality and location in Pseudomonas oleovorans inclusions containing polyhydroxyoctanoate
International Journal of Biological Macromolecules, 1996Co-Authors: E. S. Stuart, Robert W. Lenz, L J R Foster, R. C. FullerAbstract:Abstract Microbial poly-3-hydroxyoctanoate inclusion bodies produced by Pseudomonas oleovorans when grown on n -octanoic acid, are complex macromolecular structures consisting of polyester, organized paracrystalline lattice arrays and lipids. While it is known that the polymer in the granules maintains its native, amorphous state while it is surrounded by the components of this complex, the precise functions of the various components during polymer production and utilization have yet to be established. By utilizing electron microscopy, SDS-PAGE, and gel filtration chromatography along with in vitro assays for depolymerase activity, the present study demonstrates that a protein species with molecular weight of ∼ 32 kDa is the depolymerase protein of the polymer inclusion. When exogenous carbon was exhausted, cell viability required utilization of the stored polyester. Under these conditions, the concentration of the depolymerase increased while the concentrations of the polymerase decreased. Thus, the association of the depolymerase with the granules was shown to be under metabolic regulation relative to the polymerase. The results from the present studies show that careful manipulation of the substrate concentration can selectively, and differentially, alter the level of inclusion associated proteins as well as the quantity and quality of the polyester which is accumulated.
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poly 3 hydroxyalkanoates containing unsaturated repeating units produced by Pseudomonas oleovorans
Journal of Polymer Science Part A, 1995Co-Authors: R. W. Lenz, R. C. FullerAbstract:Poly-3-hydroxyalkanoates (PHAs) containing repeating units with terminal alkene substituents at the 3-position were produced by Pseudomonas oleovorans grown with either 7-octeneoic acid [OA()] alone, or 10-undeceneoic acid [UND()] alone, or mixtures of UND() and either nonanoic acid (NA) or octanoic acid (OA). For the latter, the biomass and PHA yields decreased as the fraction of UND() increased in the mixed carbon substrates. Essentially all of the repeating units in the PHA obtained from cells grown with UND() alone contained terminal alkene groups, including 3-hydroxy-10-undeceneoate, 3-hydroxy-8-noneneoate, and 3-hydroxy-6-hepteneoate units, but less than half of the units in the PHA from OA() had alkene substituents. The PHAs obtained from cells grown with various mixtures of UND() and either OA or NA were random copolymers, and the fraction of units with alkene substituents in these polymers increased in proportion to the fraction of UND() in the mixed carbon substrates. © 1995 John Wiley & Sons, Inc.
Jianmeng Chen - One of the best experts on this subject based on the ideXlab platform.
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biodegradation kinetics of tetrahydrofuran benzene toluene and ethylbenzene as multi substrate by Pseudomonas oleovorans dt4
International Journal of Environmental Research and Public Health, 2014Co-Authors: Dongzhi Chen, Jiexu Ye, Yuyang Zhou, Yunfeng Ding, Jianmeng ChenAbstract:The biodegradation kinetics of tetrahydrofuran, benzene (B), toluene (T), and ethylbenzene (E) were systematically investigated individually and as mixtures by a series of aerobic batch degradation experiments initiated by Pseudomonas oleovorans DT4. The Andrews model parameters, e.g., maximum specific growth rates (μmax), half saturation, and substrate inhibition constant, were obtained from single-substrate experiments. The interaction parameters in the sum kinetics model (SKIP) were obtained from the dual substrates. The μmax value of 1.01 for tetrahydrofuran indicated that cell growth using tetrahydrofuran as carbon source was faster than the growth on B (μmax, B = 0.39) or T (μmax, T = 0.39). The interactions in the dual-substrate experiments, including genhancement, inhibition, and co-metabolism, in the mixtures of tetrahydrofuran with B or T or E were identified. The degradation of the four compounds existing simultaneously could be predicted by the combination of SKIP and co-metabolism models. This study is the first to quantify the interactions between tetrahydrofuran and BTE.
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Biodegradation of tetrahydrofuran by combined immobilized of Pseudomonas oleovorans DT4
Environmental Sciences, 2013Co-Authors: Qian Shao, Du-juan Ouyang, Jiexu Ye, Jianmeng Chen, Dongzhi ChenAbstract:: A new composite matrix, calcium alginate (CA) coupled with activated carbon fiber (ACF) was designed to immobilize the cells of Pseudomonas oleovorans DT4 for tetrahydrofuran (THF) degradation. The average removal rate of the CA-ACF immobilized cells reached 24.0 mg x (L x h)(-1) with an initial THF concentration of 360 mg x L(-1) when the concentration of CA and ACF was 3% and 1.5% respectively. The mechanical strength of the mobilized cells was also significantly improved with the addition of ACF. Compared to the free suspended cells, higher stable removal efficiency (more than 80%) of CA-ACF cells was detected under different conditions of temperature and pH. The feasibility of the newly designed matrix was also reflected by the repeated batch degradation which showed that the removal activity decreased insignificantly after 80 cycles with the modified reaction system (PNS).
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Biodegradation of tetrahydrofuran by Pseudomonas oleovorans DT4 immobilized in calcium alginate beads impregnated with activated carbon fiber: mass transfer effect and continuous treatment.
Bioresource Technology, 2013Co-Authors: Dongzhi Chen, Jun-yi Fang, Jiexu Ye, Du-juan Ouyang, Qian Shao, Jianmeng ChenAbstract:Abstract A novel entrapment matrix, calcium alginate (CA) coupled with activated carbon fiber (ACF), was prepared to immobilize Pseudomonas oleovorans DT4 for degrading tetrahydrofuran (THF). The addition of 1.5% ACF increased the adsorption capacity of the immobilized bead, thus resulting in an enhanced average removal rate of 30.3 mg/(L h). The synergism between adsorption and biodegradation was observed in the hybrid CA–ACF beads instead of in the system comprising CA beads and freely suspended ACF. The effective diffusion coefficient of the CA–ACF bead was not significantly affected by bead size, but the bead’s value of 1.14 × 10 −6 cm 2 /s (for the bead diameter of 0.4 cm) was larger than that of the CA bead by almost one order of magnitude based on the intraparticle diffusion–reaction kinetics analysis. Continuous treatment of the THF-containing wastewater was succeeded by CA–ACF immobilized cells in a packed-bed reactor for 54 d with a >90% removal efficiency.
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substrate interactions during the biodegradation of btex and thf mixtures by Pseudomonas oleovorans dt4
Bioresource Technology, 2011Co-Authors: Yuyang Zhou, Dongzhi Chen, Jianmeng ChenAbstract:Abstract The efficient tetrahydrofuran (THF)-degrading bacterium, Pseudomonas oleovorans DT4 was used to investigate the substrate interactions during the aerobic biotransformation of THF and BTEX mixtures. Benzene and toluene could be utilized as growth substrates by DT4, whereas cometabolism of m -xylene, p -xylene and ethylbenzene occurred with THF. In binary mixtures, THF degradation was delayed by xylene, ethylbenzene, toluene and benzene in descending order of inhibitory effects. Conversely, benzene (or toluene) degradation was greatly enhanced by THF leading to a higher degradation rate of 39.68 mg/(h g dry weight) and a shorter complete degradation time about 21 h, possibly because THF acted as an “energy generator”. Additionally, the induction experiments suggested that BTEX and THF degradation was initiated by independent and inducible enzymes. The transient intermediate hydroquinone was detected in benzene biodegradation with THF while catechol in the process without THF, suggesting that P. oleovorans DT4 possessed two distinguished benzene pathways.
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characteristics of tetrahydrofuran degradation by Pseudomonas oleovorans dt4
Environmental Sciences, 2011Co-Authors: Yuyang Zhou, Dongzhi Chen, Jianmeng Chen, Jie HeAbstract:: A tetrahydrofuran (THF)-degrading strain Pseudomonas oleovorans DT4 was isolated from the activated sludge of a pharmaceutical plant. P. oleovorans DT4 was able to utilize THF as the sole carbon and energy source under aerobic condition. 5 mmol/L of THF could be completely degraded by 3.2 mg/L inoculums of P. oleovorans DT4 in 14 h at pH 7.2 and 30 degrees C, with the cells concentration increasing to 188.6 mg/L. After the complete consumption of THF, no TOC could be detected but IC reached the stable value of about 46 mg/L, with pH decreasing to 6.54, which indicated that the substance was totally mineralized by P. oleovorans DT4. The optimum conditions for THF biodegradation in shaking flasks were pH 7.5 and temperature 37 degrees C, respectively. Results from the oxygen control experiments revealed that the oxygen supply by shaking was the satisfactory growth condition. Additionally, as the important elements for DT4, Mg2+ and Ca2+ at concentrations of 0.80 mmol/L and 0.20 mmol/L, respectively, were suitable for THF degradation. All the results contribute to the efficient bioremediation for the THF contaminated.
