Cytotoxicity of polyhydroxyalkanoates in animal cell cultures.
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3T3 Cells↗
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[Organization and regulation of polyhydroxybutyrate/valerate biosynthesis in bacteria].
Recent data on the biosynthesis of poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHB/V) and its regulation in bacteria are reviewed, with special emphasis on the properties and regulation of the relevant enzymes and their genes. Some conditions promoting the synthesis of PHB and PHB/V by natural, mutant, and recombinant producers are considered.
Bacteria↗
[Use of poly-beta-oxybutyric acid by Yersinia pseudotuberculosis and Listeria monocytegenes bacteria at various temperatures].
A comparative investigation of the intracellular content of poly-beta-hydroxybutyric acid showed that Yersinia pseudotuberculosis strains accumulated, on the average, lower amounts of this reserve substance than Listeria monocytogenes strains. The intracellular pool of poly-beta-hydroxybutyric acid was responsible for the growth of the bacteria at low temperatures (4-6 degrees C) in the absence of any exogenous carbon and energy source.
Hydrogen-Ion Concentration↗
Preparation and characterization of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) microspheres for the sustained release of 5-fluorouracil.
Biodegradable microspheres were prepared with poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV, 85:15 by mole ratio of hydroxybutyrate to hydroxyvalerate) by an water-in-oil-in-water (W/O/W), oil-in-water (O/W) and oil-in-oil (O/O) solvent evaporation method for the sustained release of anti-cancer drug, 5-fluorouracil (5-FU) with controlling the fabrication conditions. The shape of microspheres prepared was relatively rough due to highly crystalline property of PHBV and spherical. The efficiency of 5-FU loading into the PHBV microsphere with O/O method was over 80% compared to that 7% for microspheres by O/W method and below 1% for microspheres by a conventional W/O/W method. However, the most desirable release pattern can be achieved from the O/W method due to the cosolvent effect. The effects of preparation conditions such as the type and amount of surfactant, initial amount of loaded drug, the temperature of solvent evaporation, and etc. on the morphology for W/O/W method were investigated. Possible mechanisms of the desirable sustained release pattern for O/W system have been proposed.
Antineoplastic Agents↗
Characterization of partially transesterified poly(beta-hydroxyalkanoate)s by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry.
Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS) was used for the characterization of a partially transesterified poly(beta-hydroxyalkanoate) (PHA), a polymer produced by the bacterial strain Alcaligenes eutrophus with saponified vegetable oils as the sole carbon sources. The transesterification was carried out separately under acidic and basic conditions to obtain PHA oligomers weighing <10 kDa. The intact oligomers were detected in their cationized forms, [M + Na]+ and [M + K]+, by MALDI-TOFMS. A composition analysis, using the MALDI-TOF spectra, indicated that the oligomers obtained via acid catalysis contained a methyl 3-hydroxybutyrate end group, and those obtained by base catalysis had a methyl crotonate (olefinic) end group. In addition to hydroxybutyrate (HB), the oligomers were found to contain a small percentage of hydroxyvalerate, which was independently confirmed by gas chromatography/mass spectrometry. In comparison, analysis of a commercial PHA polymer, transesterified under identical conditions, showed only the presence of HB, i.e., a pure poly(HB) homopolymer.
Polyesters↗
[Distal clavicular fracture and dislocation of acromino-clavicular jiont treated with biopoly ligament].
OBJECTIVE: To probe into distal clavicular fracture and acromino-clavicular joint dislocation treatment. METHODS: 11 cases of distal clavicular fracture and 20 cases of acromino-clavicular joint dislocation were treated with biopoly ligament in recent 2 years. The follow-up period lasted from 3 to 24 months with an average of 16.7 months. RESULTS: Of 29 follow-up cases, 21 were excellent and 8 satisfactory. There was no redisplacement or refracture. CONCLUSION: Biopoly ligament is believed to be a good and safe material for this fracture or dislocation. This method is simple without needing a second operation for removal of implant.
Acromioclavicular Joint↗
[The adhesion and seeding of NIH3T3 fibroblast on PHB surfaces].
Biodegradable polymers have been widely used in the field of tissue engineering. The adhesive characteristic of polymer surfaces is critical for cell seeding and growth. The adhesion and growth of NIH3T3 fibroblast on poly-beta-hydroxybutrpic acid (PHB) was studied here, and the cell-surface adhesion strength was measured in a shear flow detachment assay. It showed that the critical shear stress for cell detachment was relatively low on PHB, thus cells tend to aggregate and detach from surfaces. On the other hand, cells tend to spread and formed monolayer on poly-lysine coated PHB surface. When the PHB foams scaffolds were coated by poly-lysine, the seeding percentage of cells was also greatly enhanced.
3T3 Cells↗
[The biodegradation of poly-beta-hydroxybutyrate (PHB) by a model soil community: the effect of cultivation conditions on the degradation rate and the physicochemical characteristics of PHB].
The biodegradation of films made of poly-beta-hydroxybutyrate (PHB) with a molecular mass of 1500 kDa was studied using a model soil community in the presence and absence of nitrate and at different concentrations of oxygen in the gas phase. The biodegradation of PHB was investigated with respect to changes in its molecular mass, crystallinity, and some mechanical properties.
Biodegradation, Environmental↗
Characterization of copolymer hydroxybutyrate/hydroxyvalerate from saponified vernonia, soybean, and "spent" frying oils.
Poly(beta-hydroxyalkanoate)s (PHAs) were biosynthesized by Ralstonia eutropha (formerly known as Alcaligenes eutrophus) by using saponified soybean, vernonia, and "spent" frying oils. These PHAs were isolated and characterized by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS), gas chromatography/mass spectrometry (GC/MS), proton nuclear magnetic resonance spectrometry (1H NMR), and 2-dimensional homonuclear (1H-1H) correlation spectroscopy (COSY). The analytical results revealed that the PHAs produced from saponified vernonia and soybean oils were copolymers of hydroxybutyrate (HB) and hydroxyvalerate (HV), that is, P(HB/HV)s, whereas the saponified "spent" frying oil produced only poly(beta- hydroxybutyrate) (PHB) homopolymer. MALDI-MS, GC/MS, and NMR independently confirmed the composition of the PHAs. Saponified soybean oil and vernonia oil PHAs contained approximately 4 and 1% HV units, respectively. For comparison, commercial PHB and P(HB/HV), produced by R. eutropha by using glucose and a cosubstrate of glucose and propionic acid, respectively, as carbon sources, were similarly characterized.
Dietary Fats, Unsaturated↗
[The construction of a recombined E. coli strain with stable and high production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)].
Plasmid pJMC2 was constructed by cloning the parDE fragment of RK2 into pTZ18U-PHB which harbored phaCAB from Alcaligenes eutrophus and was transferred into E. coli HMS174 and E. coli JM107 separately. It is very stable in its hosts cultured in medium without ampicillin. E. coli HMS 174(pTZ18U-PHB) and E. coli JM107(pTZ18U-PHB) produced P(3HB-co-3HB) in a low phosphate concentration medium(18 mmol/L). The proportion of 3-hydroxyvalerate(3HV) in the polymer was 5%-8%. A fed-batch culture of E. coli HMS174(pJMC2) was conduct in a 5 L automatically controlled fermentor, the final dry cell weight, P(3HB-co-3HV) content, and th 3HV proportion were 42.5 g/L, 70% and 4.9% respectively.
Culture Media↗
[Study on production of poly-beta-hydroxybutyrate by recombinant strain VG1(pTU14)].
Cloning and expression of Vitreoscilla hemoglobin gene (vgb) and lambda phage lytic genes (S-RRz) in production of Poly-beta-hydroxybutyrate(PHB) was studied in different Escherichia coli hosts such as E. coliJM105, E. coliJM109 and VG1. In the recombinant strains, VG1(pTU14) was a superior one which simultaneously contained three exogenes including vgb, S-RRz and PHB biosynthesis genes(phbCAB). The experimental results showed that after 82 hours fed-batch cult ure in LBG medium in shaking flask, cell concentration of VG1(pTU14) could reach 25.9 g/L, which was the highest PHB production ever reported, and till 52 h PHB content could be higher than 95%. Additionally, inducible cell lysis was also attained successfully in recombinant VG1(pTU14) accompanying with its high cell density culture. Therefore, VG1(pTU14) is a novel potential strain with promising prospect in industrial production of PHB.
Bacterial Proteins↗
[Effects of nitrogen feeding on the accumulation of poly-beta-hydroxybutyrate with Alcaligenes eutrophus].
On the basis of analysis of PHB fermentation processes, the effects of ammonium sulfate feeding rate at PHB formation period on the PHB accumulation by Alcaligenes eutrophus were investigated. It was shown that the complete absence of nitrogen source at PHB formation phase would lead to the decline of PHB synthetic activity, and the obvious influences of different nitrogen feeding rate on PHB synthesis were observed. Higher PHB content, but relative lower cell dry weight, PHB concentration and PHB productivity could be obtained at slower nitrogen feeding rate. The excessive nitrogen feeding rate resulted in the drop of PHB content, which led to the decrease of PHB concentration and PHB productivity. The better results could be achieved when the ammonium sulfate feeding rate was set at around 0.5 g/h.
Ammonium Sulfate↗
[Introduction of Vitreoscilla hemoglobin gene in a recombinant E. coli for PHB production].
Vitreoscilla hemoglobin gene (vgb) was introduced into the recombinant Escherichia coli VG1(pTU14) for production of poly-beta-hydroxybutyrate (PHB), in order to enhance the oxygen uptake of strain from molecular level and to solve the problem of oxygen limitation in process of fermentation. The carbon monoxide difference spectra analysis of Vitreoscilla hemoglobin (VHb) showed that vgb could be successfully expressed in VG1 (pTU14), and this expression was under the regulation of dissolved oxygen (DO). The higher amounts of VHb could be got correspond to the lower level of DO. Because of the introduction of vgb, cell growth and PHB accumulation of VG1 (pTU14) were all strongly promoted during the process of batch culture.
Bacterial Proteins↗
[Optimization of fermentation conditions for the production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) with Alcaligenes eutrophus].
A close relationship, between the initial addition time and concentration of propionate and HV fraction, was observed in shaking culture of Alcaligenes eutrophus for the production of Poly(3-hydroxybutyrate-co-3-hydroxyvalerate). The optimal initial addition time of propionate was determined at the onset of PHBV formation period. Although relatively high HV unit could be obtained under high propionate concentration, the growth and product synthetic activities were inhibited obviously. Different ratios of glucose to propionate were fed to stimulate the formation of HV unit and the results were compared. The optimizing feeding strategy of propionate was proposed based on the consideration of several fermentation index. The final cell dry weight, PHB concentration, PHB content and HV fraction in PHBV reached 52.1 g/L, 40.8 g/L, 78.3% and 16.2 mol%, respectively, Yield coefficient of HV unit to propionate and PHBV productivity were obtained to be 0.5 g/g and 0.74 g/(L/h), respectively.
Cupriavidus necator↗
[Biosynthesis and accumulation of poly(3-hydroxybutyrate) in Vibrio natriegens].
Accumulation of poly(3-hydroxybutyrate) [poly(3HB)] by V. natriegens was studied. Results indicated that V. natriegens used glucose, gluconate, fructose and molasses as carbon sources for poly(3HB) synthesis. When molasses was used, up to 28.4% of poly(3HB) to cellular dry weight was accumulated. The accumulation of poly(3HB) followed, was not simultaneously to, the cell growth. Analysis of the PHA polymerase, beta-ketothiolase, and acetoacetyl-CoA reductase showed that the poly(3HB) accumulation was correlated to the increase of their activities in cells. Poly(3HB) accumulation was also related to the de novo fatty acid synthesis, as revealed by the results that cerulenin, a specific inhibitor to the de novo fatty acid synthesis, significantly reduced accumulation of poly(3HB). Based on the results from this study, the synthetic pathway of poly(3HB) was proposed.
Cerulenin↗
[Preparation of compound biodegradable matrices and growth of vascular endothelial cell on them].
OBJECTIVE: To prepare the compound biodegradable matrices, polyglycolic acid (PGA), polylactic acid (PLA) mesh and poly-beta-hydroxybutyrate(PHB) which precoated with collagen, and to observe the growth and differentiation of bovine vascular endothelial cells on these scaffolds. METHODS: By enzymatic digestion methods, bovine vascular endothelial cell (VEC) were isolated from calf thoracic aorta, then cultured and purified. PGA, PLA, PHB meshes were dipped into cross-linked type I collagen solution, dried under vacuum frozen condition. VEC were seeded into these scaffolds. The growth of VEC on scaffolds was analyzed by MTT method. RESULTS: The collagen, PGA/collagen, PLA/collagen scaffolds were elasticity and tenacity. VEC grew better on collagen, PGA/collagen, and PLA/collagen membranes than on the PHB/collagen one. CONCLUSION: The PGA/collagen scaffold has elasticity, plasticity and tenacity. VEC grow best on it. It is an ideal scaffold for tissue engineered vessel reconstruction for it integrating both advantages of biomaterials and degradable materials.
Animals↗
[Preparation and characterization of prednisolone-poly (hydroxybutyrate-co-hydroxyvalerate) nanoparticles].
AIM: To optimize the preparation of sustained release prednisolone-poly (hydroxybutyrate-cohydroxyvalerate) (PNS-PHBV) nanospheres (NP) using the novel biodegradable materials PHBV as the carriers and PNS as a model drug. METHODS: PNS-PHBV nanospheres were prepared by ultrasonic-emulsion technique. The diameter, its distribution and Zeta potential on the surface of particles were measured by means of Zetasizer. RESULTS: The diameter of NP is in the range of 50-250 nm. The drug loading of NP increases but incorporation efficiency and Zeta potential dramatically decrease with increasing ratio of the feeding quantities of drug to those of carriers. The drug release behavior in vitro appeared to have biphasic characteristics with initial burst effect. The more burst effect, the less the diameters of nanoparticles. The longest release time was up to 32 h. CONCLUSION: The technology of preparation is reasonable and PNS-PHBV nanoparticle showed significant sustained release.
Anti-Inflammatory Agents↗
Polyhydroxyalkanoate form and polyphosphate regulation: keys to biological phosphorus and glycogen transformations?
Experimental studies with both synthetic and real domestic wastewater showed that poly-3-hydroxy-butyrate (3HB) and poly-3-hydroxy-valerate (3HV) formed in direct proportion to the acetate/propionate (Ace/Pro) ratio of the influent wastewater during Enhanced Biological Phosphorus Removal (EBPR). Acetic acid resulted in higher anaerobic phosphorus (P) release, polyhydroxyalkanoate (PHA) yield, 3HB content, and glycogen (CH) degradation. Linear regression showed that anaerobic P release (Prel) and CH degradation (CHdeg) were both a function of Ace-->3HB, but not of Pro-->3HV. Aerobic P uptake (Pup) correlated best with preceding Prel, rather than PHA (but note Prel correlated with Ace-->3HB). Aerobic CH formation (CHform) correlated best with CHdeg and 3HB. The results imply the acetate/propionate content of influent has a major influence on PHA, CH, and P transformations. Short-term increases in acetic or propionic acid increased Prel, but were always offset by corresponding changes in Pup to yield the same net P removal as the control reactor. Thus net P removal, and EBPR process performance, was probably a function of the population selected (i.e. XPAO fraction) during long-term cultivation.
Bacteria, Anaerobic↗