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Yoshiharu Doi - One of the best experts on this subject based on the ideXlab platform.
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effects of residual metal compounds and chain end structure on thermal degradation of poly 3 Hydroxybutyric Acid
Polymer Degradation and Stability, 2006Co-Authors: Kang Ju Kim, Yoshiharu Doi, Hideki AbeAbstract:Abstract Thermal degradation behaviours of poly(3-Hydroxybutyric Acid) (P(3HB); bacterial poly[( R )-3-Hydroxybutyric Acid] and synthetic poly[( R , S )-3-Hydroxybutyric Acid] samples, were examined under both isothermal and non-isothermal conditions. The inverse of number-average degree of polymerisation for all P(3HB) samples decreased linearly with degradation time during the initial stage of isothermal degradation at a temperature ranging from 170–190 °C. In addition, crotonyl unit was detected in the residual polymer samples as main ω-chain-end. These results indicate that the dominant thermal degradation reaction for P(3HB) is a random chain scission via cis -elimination reaction of P(3HB) molecules. It was found that the presence of either Ca or Mg ions enhances the depolymerisation of P(3HB) molecules, while that Zn ions hardly catalyse the reaction. As a result, a shift of thermogravimetric curves toward the lower temperature regions was observed for the P(3HB) samples containing high amounts of Ca and Mg compounds.
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Enzymatic degradation processes of poly[(R)-3-Hydroxybutyric Acid] and poly[(R)-3-Hydroxybutyric Acid-co-(R)-3-hydroxyvaleric Acid] single crystals revealed by atomic force microscopy: effects of molecular weight and second-monomer composition on ero
Biomacromolecules, 2005Co-Authors: Keiji Numata, Tadahisa Iwata, Yoshiharu Doi, Yoshihiro Kikkawa, Takeharu Tsuge, Hideki AbeAbstract:Enzymatic degradation processes of poly[(R)-3-Hydroxybutyric Acid] (P(3HB)) and poly[(R)-3-Hydroxybutyric Acid-co-(R)-3-hydroxyvaleric Acid] (P(3HB-co-3HV)) single crystals in the presence of PHB depolymerase from Ralstonia pickettii T1 were studied by real-time and static atomic force microscopy (AFM) observations. Fibril-like crystals were generated along the long axis of single crystals during the enzymatic degradation, and then the dimensions of fibril-like crystals were analyzed quantitatively. The morphologies and sizes of fibril-like crystals were dependent on the molecular weight and copolymer composition of polymers. For all samples, the crystalline thickness gradually decreased toward a tip from the root of a fibril-like crystal after enzymatic degradation for 1 h. The thinning of fibril-like crystals may be attributed to the destruction of chain-packing structure toward crystallographic c axis by the adsorption of enzyme. From the real-time AFM images, it was found that at the initial stage of degradation the enzymatic erosion started from the disordered chain-packing region in single crystals to form the grooves along the a axis. The generated fibril-like crystals deformed at a constant rate along the a axis with a constant rate after the induction time. The erosion rate at the grooves along the a axis increased with a decrease of molecular weight and with an increase of copolymer composition. On the other hand, the erosion rate along the a axis, at the tip of the fibril-like crystal, was dependent on only the copolymer composition, and the value increased with an increase in the copolymer composition. The morphologies and sizes of fibril-like crystals were governed by both the erosion rates along the a axis at the grooves and tip of fibril-like crystals. In addition, we were able to estimated the overall enzymatic erosion rate of single crystals by PHB depolymerase from the volumetric analysis.
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Crystal morphologies and enzymatic degradation of melt-crystallized thin films of random copolyesters of (R)-3-Hydroxybutyric Acid with (R)-3-hydroxyalkanoic Acids
Polymer Degradation and Stability, 2002Co-Authors: Yoshihiro Kikkawa, Tadahisa Iwata, Hideki Abe, Yoshio Inoue, Yoshiharu DoiAbstract:Abstract Spherulitic and lamellar morphologies of melt-crystallized thin films for poly[( R )-3-Hydroxybutyric Acid- co -16 mol%-( R )-3-hydroxypentanoic Acid] and poly[( R )-3-Hydroxybutyric Acid- co -8 mol%-( R )-3-hydroxyhexanoic Acid] were characterized by optical, transmission electron and atomic force microscopies. Two-dimensional spherulites were formed throughout the thin films of bacterial copolymers after isothermal crystallization at 110 °C. The second monomer units in the random copolymer chains were excluded from the crystalline regions of poly[( R )-3-Hydroxybutyric Acid] (P[( R )-3HB]) lamellar crystals during isothermal crystallization process. Formation of the thin crystals with 5–7 nm thickness was found on the surface of original lamellar crystals with 10–13 nm thickness in the course of storage at room temperature after isothermal crystallization at 110 °C. Both the thermal analysis and morphological observation of copolymer thin films suggest that a certain sequential length of ( R )-3HB units in copolymer is needed for the formation of the original lamellar crystals at a crystallization temperature. The enzymatic degradation of copolymer thin films was performed in an aqueous solution of PHB depolymerase from Ralstonia pickettii . At the initial stage of enzymatic degradation, only the thin crystals formed at room temperature were eroded by the enzyme. By the continuous degradation reaction, the original thick lamellar crystals showed a comb-like texture and grooves along the crystal growth direction, suggesting that disordered chain-packing regions are accumulated in the original lamellar crystals during crystal growth process.
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Real‐time enzymatic degradation study of poly[(R)‐3‐Hydroxybutyric Acid] copolymer thin film by atomic force microscopy in buffer solution
Macromolecular Bioscience, 2002Co-Authors: Yoshihiro Kikkawa, Tadahisa Iwata, Hideki Abe, Yoshio Inoue, Tomohide Murase, Yoshiharu DoiAbstract:In situ observation of lamellar crystals during the enzymatic degradation by poly(hydroxybytyrate) PHB depolymerase is carried out on the thin films of poly[((R)-3-Hydroxybutyric Acid)-co-(16 mol-%-(R)-3-hydroxypentanoic Acid)] using atomic force microscopy in buffer solution. Erosion of lamellar crystals and formation of splintered morphology along the crystal growth direction are directly observed during the course of the enzymatic degradation process. The changes in lamellar morphologies caused by enzymatic degradation are discussed in terms of lamellar crystal growth process.
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Crystalline morphology and thermal properties for random copolyesters of (R)‐3‐Hydroxybutyric Acid with different hydroxyalkanoic groups
Macromolecular Symposia, 2001Co-Authors: Hideki Abe, Yoshiharu DoiAbstract:The solid-state structures and thermal properties of melt-crystallized films of random copolymers of (R)-3-Hydroxybutyric Acid (3HB) with different hydroxyalkanoic Acids such as (R)-3-hydroxypentanoic Acid (3HV), (R)-3-hydroxyhexanoic Acid (3HH), medium-chain-length (R)-3-hydroxyalkanoic Acids (mcl-3HA; C8-C12), 4-Hydroxybutyric Acid (4HB), and 6-hydroxyhexanoic Acid (6HH) were characterized by means of small-angle X-ray scattering, differential scanning calorimetry, and optical microscopy. The randomly distributed second monomer units except for 3HV in copolyesters act as defects of P(3HB) crystal and are excluded from the P(3HB) crystalline lamellae. The lamellar thickness of copolymers decreased with an increase in either the main-chain or the side-chain carbon numbers of second monomer units. In addition, the growth rate of spherulites decreased with an increase in the carbon numbers of second monomer units for copolymers with an identical comonomer composition. These results indicate that the steric bulkiness of second monomer unit affects on the crystallization of 3HB segments in random copolyesters.
Yoshio Inoue - One of the best experts on this subject based on the ideXlab platform.
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Crystal morphologies and enzymatic degradation of melt-crystallized thin films of random copolyesters of (R)-3-Hydroxybutyric Acid with (R)-3-hydroxyalkanoic Acids
Polymer Degradation and Stability, 2002Co-Authors: Yoshihiro Kikkawa, Tadahisa Iwata, Hideki Abe, Yoshio Inoue, Yoshiharu DoiAbstract:Abstract Spherulitic and lamellar morphologies of melt-crystallized thin films for poly[( R )-3-Hydroxybutyric Acid- co -16 mol%-( R )-3-hydroxypentanoic Acid] and poly[( R )-3-Hydroxybutyric Acid- co -8 mol%-( R )-3-hydroxyhexanoic Acid] were characterized by optical, transmission electron and atomic force microscopies. Two-dimensional spherulites were formed throughout the thin films of bacterial copolymers after isothermal crystallization at 110 °C. The second monomer units in the random copolymer chains were excluded from the crystalline regions of poly[( R )-3-Hydroxybutyric Acid] (P[( R )-3HB]) lamellar crystals during isothermal crystallization process. Formation of the thin crystals with 5–7 nm thickness was found on the surface of original lamellar crystals with 10–13 nm thickness in the course of storage at room temperature after isothermal crystallization at 110 °C. Both the thermal analysis and morphological observation of copolymer thin films suggest that a certain sequential length of ( R )-3HB units in copolymer is needed for the formation of the original lamellar crystals at a crystallization temperature. The enzymatic degradation of copolymer thin films was performed in an aqueous solution of PHB depolymerase from Ralstonia pickettii . At the initial stage of enzymatic degradation, only the thin crystals formed at room temperature were eroded by the enzyme. By the continuous degradation reaction, the original thick lamellar crystals showed a comb-like texture and grooves along the crystal growth direction, suggesting that disordered chain-packing regions are accumulated in the original lamellar crystals during crystal growth process.
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Real‐time enzymatic degradation study of poly[(R)‐3‐Hydroxybutyric Acid] copolymer thin film by atomic force microscopy in buffer solution
Macromolecular Bioscience, 2002Co-Authors: Yoshihiro Kikkawa, Tadahisa Iwata, Hideki Abe, Yoshio Inoue, Tomohide Murase, Yoshiharu DoiAbstract:In situ observation of lamellar crystals during the enzymatic degradation by poly(hydroxybytyrate) PHB depolymerase is carried out on the thin films of poly[((R)-3-Hydroxybutyric Acid)-co-(16 mol-%-(R)-3-hydroxypentanoic Acid)] using atomic force microscopy in buffer solution. Erosion of lamellar crystals and formation of splintered morphology along the crystal growth direction are directly observed during the course of the enzymatic degradation process. The changes in lamellar morphologies caused by enzymatic degradation are discussed in terms of lamellar crystal growth process.
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Experimental approaches to generate compositional gradients in the fully biodegradable polymer blend system based on poly(3-Hydroxybutyric Acid)
Macromolecular Chemistry and Physics, 2000Co-Authors: Tetsuya Ikejima, Yoshio InoueAbstract:The fully biodegradable polymer blend films with compositional gradients from the surface to the inside of the films were prepared by the solution-diffuse technique. A solution of bacterial poly(3-Hydroxybutyric Acid) (PHB) in hexafluoro-2-propanol (HFIP), which is also a good solvent for poly(vinyl alcohol) (PVA), was cast on a PVA film and the solvent HFIP was evaporated. By controlling the solvent evaporation rate, the PHB/PVA blend film with a compositional gradient was obtained. The phase structure and biodegradation profile of the PHB/PVA blend film were found to be different from those of the corresponding blend film prepared by the conventional solution-cast method.
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biodegradable blends of high molecular weight poly ethylene oxide with poly 3 hydroxypropionic Acid and poly 3 Hydroxybutyric Acid a miscibility study by dsc dmta and nmr spectroscopy
Polymer International, 2000Co-Authors: Naoki Asakawa, Yoshio InoueAbstract:The miscibility of high molecular weight poly(ethylene oxide) blends with poly(3-hydroxypropionic Acid) and poly(3-Hydroxybutyric Acid) (P(3HB)) has been investigated by differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and high-resolution solid state 13C nuclear magnetic resonance (NMR). The DSC thermal behaviour of the blends revealed that the binary blends of poly(ethylene oxide)/poly(3-hydroxypropionic Acid) (OP blends) were miscible over the whole composition range while the miscibility of poly(ethylene oxide)/poly(3-Hydroxybutyric Acid) blends (OB blends) was dependent on the blend composition. OB blends were found to be partly miscible at the middle P(3HB) contents (25 %, 50 %) and miscible at other P(3HB) contents (10 %, 75 % and 90 %). Single-phase behaviour for OP blends and phase separation behaviour for OB blends were observed from DMTA. The results from NMR spectroscopy revealed that the two components in the OP50 blend were intimately mixed on a scale of about 35 nm, while the domain sizes in the OB blend with a P(3HB) content of 50 % were larger than about 32 nm. © 2000 Society of Chemical Industry
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Crystallization behavior and environmental biodegradability of the blend films of poly(3-Hydroxybutyric Acid) with chitin and chitosan
Carbohydrate Polymers, 2000Co-Authors: T Ikejima, Yoshio InoueAbstract:Crystallization behavior and environmental biodegradability were investigated for the films of bacterial poly(3-Hydroxybutyric Acid) (PHB) blends with chitin and chitosan. The blend films showed X-ray diffractive peaks that arose from the PHB crystalline component. It was suggested that the lamellar thickness of the PHB crystalline component in the blends was large enough to show detectable X-ray diffractive peaks, but this was too small to show observable melting endotherm in the DSC thermogram and the crystalline band absorption in the FT-IR spectrum. In the PHB/chitin and PHB/chitosan blends, thermal transition temperatures of PHB amorphous region observed by dynamic mechanical thermal analysis were almost the same as that of neat PHB. Both the PHB/chitin and the PHB/chitosan blend films biodegraded in an environmental medium. Several blend films showed faster biodegradation than the pure-state component polymers.
Yoshikazu Kawata - One of the best experts on this subject based on the ideXlab platform.
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Improvement of (R)-3-Hydroxybutyric Acid secretion during Halomonas sp. KM-1 cultivation with saccharified Japanese cedar by the addition of urea.
Letters in applied microbiology, 2015Co-Authors: Yoshikazu Kawata, Masanobu Nojiri, Isao Matsushita, Jun TsubotaAbstract:UNLABELLED Japanese cedar (Cryptomeria japonica) is a major species in artificial Japanese forests. The Halomonas sp. KM-1 was recently isolated and found to grow effectively on saccharified Japanese cedar wood, resulting in the intracellular storage of poly-(R)-3-Hydroxybutyric Acid (PHB) under aerobic conditions. Under microaerobic conditions, the extracellular secretion of (R)-3-Hydroxybutyric Acid ((R)-3-HB) led to the degradation of intracellular PHB. In this study, the production of PHB and the secretion of (R)-3-HB using saccharified Japanese cedar were much improved in cultures that were grown in the presence of urea. The level of intracellular PHB production after 36 h under aerobic cultivation was 23·6 g l(-1) ; after shifting to microaerobic conditions for 24 h, the (R)-3-HB concentration in the medium reached 21·1 g l(-1) . Thus, KM-1 efficiently utilizes saccharified Japanese cedar to produce PHB and secretes (R)-3-HB, making it a practical candidate for use in the industrial production of (R)-3-HB. SIGNIFICANCE AND IMPACT OF THE STUDY Japanese cedar is a major species grown in artificial Japanese forests, and its thinning is crucial for the health of artificial forests and the Japanese economy. Halomonas sp. KM-1 grew effectively on saccharified Japanese cedar wood, resulting in intracellular storage of poly-(R)-3-Hydroxybutyric Acid (PHB) under aerobic conditions. Under microaerobic conditions, extracellular secretion of (R)-3-Hydroxybutyric Acid ((R)-3-HB) caused intracellular PHB degradation. (R)-3-HB is a chiral compound that is useful in the chemical, health food and pharmaceutical industries. The production of PHB and secretion of (R)-3-HB using saccharified wood was dramatically improved, which may positively affect its future industrial production.
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Efficient secretion of (R)-3-Hydroxybutyric Acid from Halomonas sp. KM-1 by nitrate fed-batch cultivation with glucose under microaerobic conditions.
Bioresource technology, 2014Co-Authors: Yoshikazu Kawata, Isao Matsushita, Hitoshi Ando, Jun TsubotaAbstract:To establish a sustainable society, commodity chemicals need to be developed from biomass resources. Recently, (R)-3-Hydroxybutyric Acid ((R)-3-HB), a monomer of bioplastic poly-(R)-3-Hydroxybutyric Acid (PHB), has attracted attention for its possible use in the chemical industry. Halophilic bacteria have been considered for bioprocess applications due to certain characteristics such as the ability to grow in media containing high levels of the starting carbon source and the ability to be rarely contaminated. A halophilic bacterium Halomonas sp. KM-1 stores PHB intracellularly under aerobic conditions and secretes (R)-3-HB under microaerobic conditions. In this study, we optimized culture conditions to maximize (R)-3-HB secretion by KM-1 cells. By a simple nitrate fed-batch cultivation, Halomonas sp. KM-1 secreted 40.3g/L (R)-3-HB with a productivity of 0.48g L(-1)h(-1) with 20% (w/v) glucose. This level is one of the highest recorded productivity of (R)-3-HB to date.
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Efficient secretion of (R)-3-Hydroxybutyric Acid from Halomonas sp. KM-1 cultured with saccharified Japanese cedar under microaerobic conditions
Bioresource technology, 2013Co-Authors: Yoshikazu Kawata, You-xun Jin, Masanobu NojiriAbstract:In the presence of d-glucose, consumption of pentoses such as d-xylose is somewhat repressed by most bacteria. However, in Halomonas sp. KM-1, simultaneous utilization of a pure hexose and pentose for growth and PHB production has been observed. Moreover, this strain has been shown to preferentially utilize d-xylose from a mixture of hexose and pentose. In addition, the KM-1 strain produced (R)-3-Hydroxybutyric Acid ((R)-3-HB) by using saccharified Japanese cedar (Cryptomeria japonica) wood. The concentration of intracellular PHB after aerobic cultivation for 24h was 8.4 g/L, and after shifting to microaerobic conditions and further cultivation for 18 h, the concentration of (R)-3-HB in the medium reached 8.0 g/L. These results show that the KM-1 strain can efficiently utilize saccharified Japanese cedar and secreted (R)-3-HB under microaerobic conditions.
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Efficient secreted production of (R)-3-Hydroxybutyric Acid from living Halomonas sp. KM-1 under successive aerobic and microaerobic conditions.
Applied microbiology and biotechnology, 2012Co-Authors: Yoshikazu Kawata, Kazunori Kawasaki, Yasushi ShigeriAbstract:Production of (R)-3-Hydroxybutyric Acid [(R)-3-HB] by strain Halomonas sp. KM-1 under successive aeration conditions was investigated. The first aerobic condition allowed both cell growth and intracellular storage of poly-(R)-3-Hydroxybutyric Acid (PHB). The second microaerobic condition, achieved by reducing the culture agitation rate, lead to the degradation of PHB to (R)-3-HB. The amount of PHB stored in KM-1 cells after 48-h cultivation under aerobic conditions was 16.4 g/l. In contrast, after a shift from aerobic to microaerobic conditions and a further 18-h cultivation, PHB content in KM-1 cells decreased to 0.9 g/l. Numerous intracellular PHB-containing granules were observed in cells under aerobic conditions by electron microscopy. After the shift to microaerobic conditions, the number and size of granules were significantly reduced, in agreement with the degradation of prestored PHB. On the other hand, under microaerobic conditions, the concentration of (R)-3-HB in the medium reached a maximum of 15.2 g/l, indicating the production and extracellular secretion of (R)-3-HB as a result of PHB digestion. Notably, cell lysis was not observed during the successive aeration conditions as assessed by elution of genomic DNA to the culture supernatant, cell morphology observed by electron microscopy and counts of colony formation. In this simple system utilizing a change of aeration during cultivation of strain Halomonas sp. KM-1, we obtained one of the highest levels of microbiological production of (R)-3-HB reported to date.
Hideki Abe - One of the best experts on this subject based on the ideXlab platform.
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effects of residual metal compounds and chain end structure on thermal degradation of poly 3 Hydroxybutyric Acid
Polymer Degradation and Stability, 2006Co-Authors: Kang Ju Kim, Yoshiharu Doi, Hideki AbeAbstract:Abstract Thermal degradation behaviours of poly(3-Hydroxybutyric Acid) (P(3HB); bacterial poly[( R )-3-Hydroxybutyric Acid] and synthetic poly[( R , S )-3-Hydroxybutyric Acid] samples, were examined under both isothermal and non-isothermal conditions. The inverse of number-average degree of polymerisation for all P(3HB) samples decreased linearly with degradation time during the initial stage of isothermal degradation at a temperature ranging from 170–190 °C. In addition, crotonyl unit was detected in the residual polymer samples as main ω-chain-end. These results indicate that the dominant thermal degradation reaction for P(3HB) is a random chain scission via cis -elimination reaction of P(3HB) molecules. It was found that the presence of either Ca or Mg ions enhances the depolymerisation of P(3HB) molecules, while that Zn ions hardly catalyse the reaction. As a result, a shift of thermogravimetric curves toward the lower temperature regions was observed for the P(3HB) samples containing high amounts of Ca and Mg compounds.
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Enzymatic degradation processes of poly[(R)-3-Hydroxybutyric Acid] and poly[(R)-3-Hydroxybutyric Acid-co-(R)-3-hydroxyvaleric Acid] single crystals revealed by atomic force microscopy: effects of molecular weight and second-monomer composition on ero
Biomacromolecules, 2005Co-Authors: Keiji Numata, Tadahisa Iwata, Yoshiharu Doi, Yoshihiro Kikkawa, Takeharu Tsuge, Hideki AbeAbstract:Enzymatic degradation processes of poly[(R)-3-Hydroxybutyric Acid] (P(3HB)) and poly[(R)-3-Hydroxybutyric Acid-co-(R)-3-hydroxyvaleric Acid] (P(3HB-co-3HV)) single crystals in the presence of PHB depolymerase from Ralstonia pickettii T1 were studied by real-time and static atomic force microscopy (AFM) observations. Fibril-like crystals were generated along the long axis of single crystals during the enzymatic degradation, and then the dimensions of fibril-like crystals were analyzed quantitatively. The morphologies and sizes of fibril-like crystals were dependent on the molecular weight and copolymer composition of polymers. For all samples, the crystalline thickness gradually decreased toward a tip from the root of a fibril-like crystal after enzymatic degradation for 1 h. The thinning of fibril-like crystals may be attributed to the destruction of chain-packing structure toward crystallographic c axis by the adsorption of enzyme. From the real-time AFM images, it was found that at the initial stage of degradation the enzymatic erosion started from the disordered chain-packing region in single crystals to form the grooves along the a axis. The generated fibril-like crystals deformed at a constant rate along the a axis with a constant rate after the induction time. The erosion rate at the grooves along the a axis increased with a decrease of molecular weight and with an increase of copolymer composition. On the other hand, the erosion rate along the a axis, at the tip of the fibril-like crystal, was dependent on only the copolymer composition, and the value increased with an increase in the copolymer composition. The morphologies and sizes of fibril-like crystals were governed by both the erosion rates along the a axis at the grooves and tip of fibril-like crystals. In addition, we were able to estimated the overall enzymatic erosion rate of single crystals by PHB depolymerase from the volumetric analysis.
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Crystal morphologies and enzymatic degradation of melt-crystallized thin films of random copolyesters of (R)-3-Hydroxybutyric Acid with (R)-3-hydroxyalkanoic Acids
Polymer Degradation and Stability, 2002Co-Authors: Yoshihiro Kikkawa, Tadahisa Iwata, Hideki Abe, Yoshio Inoue, Yoshiharu DoiAbstract:Abstract Spherulitic and lamellar morphologies of melt-crystallized thin films for poly[( R )-3-Hydroxybutyric Acid- co -16 mol%-( R )-3-hydroxypentanoic Acid] and poly[( R )-3-Hydroxybutyric Acid- co -8 mol%-( R )-3-hydroxyhexanoic Acid] were characterized by optical, transmission electron and atomic force microscopies. Two-dimensional spherulites were formed throughout the thin films of bacterial copolymers after isothermal crystallization at 110 °C. The second monomer units in the random copolymer chains were excluded from the crystalline regions of poly[( R )-3-Hydroxybutyric Acid] (P[( R )-3HB]) lamellar crystals during isothermal crystallization process. Formation of the thin crystals with 5–7 nm thickness was found on the surface of original lamellar crystals with 10–13 nm thickness in the course of storage at room temperature after isothermal crystallization at 110 °C. Both the thermal analysis and morphological observation of copolymer thin films suggest that a certain sequential length of ( R )-3HB units in copolymer is needed for the formation of the original lamellar crystals at a crystallization temperature. The enzymatic degradation of copolymer thin films was performed in an aqueous solution of PHB depolymerase from Ralstonia pickettii . At the initial stage of enzymatic degradation, only the thin crystals formed at room temperature were eroded by the enzyme. By the continuous degradation reaction, the original thick lamellar crystals showed a comb-like texture and grooves along the crystal growth direction, suggesting that disordered chain-packing regions are accumulated in the original lamellar crystals during crystal growth process.
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Real‐time enzymatic degradation study of poly[(R)‐3‐Hydroxybutyric Acid] copolymer thin film by atomic force microscopy in buffer solution
Macromolecular Bioscience, 2002Co-Authors: Yoshihiro Kikkawa, Tadahisa Iwata, Hideki Abe, Yoshio Inoue, Tomohide Murase, Yoshiharu DoiAbstract:In situ observation of lamellar crystals during the enzymatic degradation by poly(hydroxybytyrate) PHB depolymerase is carried out on the thin films of poly[((R)-3-Hydroxybutyric Acid)-co-(16 mol-%-(R)-3-hydroxypentanoic Acid)] using atomic force microscopy in buffer solution. Erosion of lamellar crystals and formation of splintered morphology along the crystal growth direction are directly observed during the course of the enzymatic degradation process. The changes in lamellar morphologies caused by enzymatic degradation are discussed in terms of lamellar crystal growth process.
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Crystalline morphology and thermal properties for random copolyesters of (R)‐3‐Hydroxybutyric Acid with different hydroxyalkanoic groups
Macromolecular Symposia, 2001Co-Authors: Hideki Abe, Yoshiharu DoiAbstract:The solid-state structures and thermal properties of melt-crystallized films of random copolymers of (R)-3-Hydroxybutyric Acid (3HB) with different hydroxyalkanoic Acids such as (R)-3-hydroxypentanoic Acid (3HV), (R)-3-hydroxyhexanoic Acid (3HH), medium-chain-length (R)-3-hydroxyalkanoic Acids (mcl-3HA; C8-C12), 4-Hydroxybutyric Acid (4HB), and 6-hydroxyhexanoic Acid (6HH) were characterized by means of small-angle X-ray scattering, differential scanning calorimetry, and optical microscopy. The randomly distributed second monomer units except for 3HV in copolyesters act as defects of P(3HB) crystal and are excluded from the P(3HB) crystalline lamellae. The lamellar thickness of copolymers decreased with an increase in either the main-chain or the side-chain carbon numbers of second monomer units. In addition, the growth rate of spherulites decreased with an increase in the carbon numbers of second monomer units for copolymers with an identical comonomer composition. These results indicate that the steric bulkiness of second monomer unit affects on the crystallization of 3HB segments in random copolyesters.
Sang Yup Lee - One of the best experts on this subject based on the ideXlab platform.
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Biosynthesis of enantiopure (S)-3-Hydroxybutyric Acid in metabolically engineered Escherichia coli.
Applied microbiology and biotechnology, 2008Co-Authors: Sang-hyun Lee, Sang Yup Lee, Si Jae Park, Soon Ho HongAbstract:A biosynthetic pathway for the production of (S)-3-Hydroxybutyric Acid (S3HB) from glucose was established in recombinant Escherichia coli by introducing the beta-ketothiolase gene from Ralstonia eutropha H16, the (S)-3-hydroxybutyryl-CoA dehydrogenase gene from R. eutropha H16, or Clostridium acetobutylicum ATCC824, and the 3-hydroxyisobutyryl-CoA hydrolase gene from Bacillus cereus ATCC14579. Artificial operon consisting of these genes was constructed and was expressed in E. coli BL21 (DE3) codon plus under T7 promoter by isopropyl beta-D: -thiogalactoside (IPTG) induction. Recombinant E. coli BL21 (DE3) codon plus expressing the beta-ketothiolase gene, the (S)-3-hydroxybutyryl-CoA dehydrogenase gene, and the 3-hydroxyisobutyryl-CoA hydrolase gene could synthesize enantiomerically pure S3HB to the concentration of 0.61 g l(-1) from 20 g l(-1) of glucose in Luria-Bertani medium. Fed-batch cultures of recombinant E. coli BL21 (DE3) codon plus were carried out to achieve higher titer of S3HB with varying induction time and glucose concentration during fermentation. Protein expression was induced by addition of 1 mM IPTG when cell concentration reached 10 and 20 g l(-1) (OD(600) = 30 and 60), respectively. When protein expression was induced at 60 of OD(600) and glucose was fed to the concentration of 15 g l(-1), 10.3 g l(-1) of S3HB was obtained in 38 h with the S3HB productivity of 0.21 g l(-1)h(-1). Lowering glucose concentration to 5 g l(-1) and induction of protein expression at 30 of OD(600) significantly reduced final S3HB concentration to 3.7 g l(-1), which also resulted in the decrease of the S3HB productivity to 0.05 g l(-1)h(-1).
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biosynthesis of enantiopure s 3 Hydroxybutyric Acid in metabolically engineered escherichia coli
Applied Microbiology and Biotechnology, 2008Co-Authors: Sang-hyun Lee, Sang Yup Lee, Si Jae Park, Soon Ho HongAbstract:A biosynthetic pathway for the production of (S)-3-Hydroxybutyric Acid (S3HB) from glucose was established in recombinant Escherichia coli by introducing the β-ketothiolase gene from Ralstonia eutropha H16, the (S)-3-hydroxybutyryl-CoA dehydrogenase gene from R. eutropha H16, or Clostridium acetobutylicum ATCC824, and the 3-hydroxyisobutyryl-CoA hydrolase gene from Bacillus cereus ATCC14579. Artificial operon consisting of these genes was constructed and was expressed in E. coli BL21 (DE3) codon plus under T7 promoter by isopropyl β-d-thiogalactoside (IPTG) induction. Recombinant E. coli BL21 (DE3) codon plus expressing the β-ketothiolase gene, the (S)-3-hydroxybutyryl-CoA dehydrogenase gene, and the 3-hydroxyisobutyryl-CoA hydrolase gene could synthesize enantiomerically pure S3HB to the concentration of 0.61 g l−1 from 20 g l−1 of glucose in Luria–Bertani medium. Fed-batch cultures of recombinant E. coli BL21 (DE3) codon plus were carried out to achieve higher titer of S3HB with varying induction time and glucose concentration during fermentation. Protein expression was induced by addition of 1 mM IPTG when cell concentration reached 10 and 20 g l−1 (OD600 = 30 and 60), respectively. When protein expression was induced at 60 of OD600 and glucose was fed to the concentration of 15 g l−1, 10.3 g l−1 of S3HB was obtained in 38 h with the S3HB productivity of 0.21 g l−1h−1. Lowering glucose concentration to 5 g l−1 and induction of protein expression at 30 of OD600 significantly reduced final S3HB concentration to 3.7 g l−1, which also resulted in the decrease of the S3HB productivity to 0.05 g l−1h−1.
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Molecular mass of poly[(R )-3-Hydroxybutyric Acid] produced in a recombinant Escherichia coli
Applied microbiology and biotechnology, 1997Co-Authors: S. Kusaka, Sang Yup Lee, H. Abe, Yoshiharu DoiAbstract:Poly[(R)-3-Hydroxybutyric Acid] (PHB) was produced at 37 degrees C by a recombinant Escherichia coli harboring the Alcaligenes eutrophus biosynthesis phb-CAB genes in Luria-Bertani media containing glucose at 10-30 g/l at different pH values and the time-dependent changes in the molecular mass of PHB were studied. PHB polymers accumulated within cells while glucose was present in the medium. The number-average molecular mass of PHB decreased with time during the course of PHB accumulation, and the values for PHB were markedly dependent on the cultivation conditions of the E. coli, ranging from 0.5 MDa to 20 MDa. Under specific conditions (pH 6.0), E. coli produced PHB with an extremely high molecular mass (20 MDa). It has been suggested that a chain-transfer agent is generated in E. coli cells during the accumulation of PHB.
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Production of poly(3-Hydroxybutyric Acid) by recombinant Escherichia coli strains: genetic and fermentation studies
Canadian Journal of Microbiology, 1995Co-Authors: Sang Yup Lee, Ho Nam ChangAbstract:A number of Escherichia coli strains including K12, B, W, XL1-Blue, DH5α, HB101, JM109, and C600 were transformed with the stable high-copy-number plasmid pSYL105 containing the Alcaligenes eutrophus polyhydroxyalkanoic Acid biosynthesis genes, and were subsequently compared for their ability to synthesize and accumulate poly(3-Hydroxybutyric Acid) (PHB). The rate of PHB synthesis, the extent of PHB accumulation, and PHB yield from glucose varied considerably from one strain to another. Strains XL1-Blue and B harboring pSYL105 synthesized PHB at the highest rate to a final concentration of ca. 7 g/L in complex medium containing 20 g glucose/L. With an aim to reduce the cost of the medium, the effect on PHB accumulation of supplementing a defined medium with complex nitrogen sources was examined. A PHB concentration of 81 g/L could be obtained in 41 h from a pH-stat fed-batch culture of XL1-Blue(pSYL105) in a semidefined medium. When the availability of acetyl-CoA was increased by supplementing the medium ...
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STIMULATORY EFFECTS OF AMINO-AcidS AND OLEIC-Acid ON POLY(3-Hydroxybutyric Acid) SYNTHESIS BY RECOMBINANT ESCHERICHIA-COLI
Journal of Fermentation and Bioengineering, 1995Co-Authors: Sang Yup Lee, Yoo Kyung Lee, Ho Nam ChangAbstract:Addition of cysteine, isoleucine, methionine, or proline promoted poly(3-Hydroxybutyric Acid) [PHB] synthesis by recombinant Escherichia coli more than two-fold. Oleic Acid also enhanced PHB synthesis more than three-fold. A PHB concentration of 70 g/l could be obtained by fed-batch culture of recombinant E. coli in a defined medium supplemented with small amounts of isoleucine, methionine, and proline. The stimulatory effects of amino Acids and oleic Acid on PHB synthesis seems to be due to the availability of more acetyl-CoA and/or NADPH.
