Research progress on medical devices of polyhydroxyalkanoate in orthopedics / 中国修复重建外科杂志

OBJECTIVE@#To review the research progress of natural biomaterial polyhydroxyalkanoate (PHA) in orthopedics.@*METHODS@#The literature concerning PHA devices for bone defects, bone repair, and bone neoplasms, respectively, in recent years was extensively consulted. The three aspects of the advantages of PHA in bone repair, the preparation of PHA medical devices for bone repair and their application in orthopedics were discussed.@*RESULTS@#Due to excellent biodegradability, biocompatibility, and potential osteoinduction, PHA is a kind of good bone repair material. In addition to the traditional PHA medical implants, the use of electrostatic spinning and three-dimensional printing can be designed to various functional PHA medical devices, in order to meet the orthopedic clinical demands, including the bone regeneration, minimally invasive bone tissue repair by injection, antibacterial bone repair, auxiliary establishment of three-dimensional bone tumor model, directed osteogenic differentiation of stem cells, etc.@*CONCLUSION@#At present, PHA is a hotspot of biomaterials for translational medicine in orthopedics. Although they have not completely applied in the clinic, the advantages of repair in bone defects have been gradually reflected in tissue engineering, showing an application prospect in orthopedics.

An examination of the carbon metabolic pathways in Acinetobacter sp. TAC-1 in the context of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) utilization / 生物工程学报

The present study aimed to unravel the carbon metabolism pathway of Acinetobacter sp. TAC-1, a heterotrophic nitrification-aerobic denitrification (HN-AD) strain that utilizes poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) as a carbon source. Sodium acetate was employed as a control to assess the gene expression of carbon metabolic pathways in the TAC-1 strain. The results of genome sequencing demonstrated that the TAC-1 strain possessed various genes encoding carbon metabolic enzymes, such as gltA, icd, sucAB, acs, and pckA. KEGG pathway database analysis further verified the presence of carbon metabolism pathways, including the glycolytic pathway (EMP), pentose phosphate pathway (PPP), glyoxylate cycle (GAC), and tricarboxylic acid (TCA) cycle in the TAC-1 strain. The differential expression of metabolites derived from distinct carbon sources provided further evidence that the carbon metabolism pathway of TAC-1 utilizing PHBV follows the sequential process of PHBV (via the PPP pathway)→gluconate (via the EMP pathway)→acetyl-CoA (entering the TCA cycle)→CO2+H2O (generating electron donors and releasing energy). This study is expected to furnish a theoretical foundation for the advancement and implementation of novel denitrification processes based on HN-AD and solid carbon sources.

Expression and characterization of a novel halohydrin dehalogenase from Rhodospirillaceae bacterium / 生物工程学报

As a class of multifunctional biocatalysts, halohydrin dehalogenases are of great interest for the synthesis of chiral β-substituted alcohols and epoxides. There are less than 40 halohydrin dehalogenases with relatively clear catalytic functions, and most of them do not meet the requirements of scientific research and practical applications. Therefore, it is of great significance to excavate and identify more halohydrin dehalogenases. In the present study, a putative halohydrin dehalogenase (HHDH-Ra) from Rhodospirillaceae bacterium was expressed and its enzymatic properties were investigated. The HHDH-Ra gene was cloned into the expression host Escherichia coli BL21(DE3) and the target protein was shown to be soluble. Substrate specificity studies showed that HHDH-Ra possesses excellent specificity for 1,3-dichloro-2-propanol (1,3-DCP) and ethyl-4-chloro-3-hydroxybutyrate (CHBE). The optimum pH and temperature for HHDH-Ra with 1,3-DCP as the reaction substrate were 8.0 and 30 °C, respectively. HHDH-Ra was stable at pH 6.0-8.0 and maintained about 70% of its original activity after 100 h of treatment. The thermal stability results revealed that HHDH-Ra has a half-life of 60 h at 30 °C and 40 °C. When the temperature is increased to 50 °C, the enzyme still has a half-life of 20 h, which is much higher than that of the reported enzymes. To sum up, the novel halohydrin dehalogenase from Rhodospirillaceae bacterium possesses good temperature and pH stability as well as catalytic activity, and shows the potential to be used in the synthesis of chemical and pharmaceutical intermediates.

Respiration in Azotobacter vinelandii and its relationship with the synthesis of biopolymers

Azotobacter vinelandii is a gram-negative soil bacterium that produces two biopolymers of biotechnological interest, alginate and poly(3-hydroxybutyrate), and it has been widely studied because of its capability to fix nitrogen even in the presence of oxygen. This bacterium is characterized by its high respiration rates, which are almost 10-fold higher than those of Escherichia coli and are a disadvantage for fermentation processes. On the other hand, several works have demonstrated that adequate control of the oxygen supply in A. vinelandii cultivations determines the yields and physicochemical characteristics of alginate and poly(3-hydroxybutyrate). Here, we summarize a review of the characteristics of A. vinelandii related to its respiration systems, as well as some of the most important findings on the oxygen consumption rates as a function of the cultivation parameters and biopolymer production.

Bioconversion of sugarcane molasses to poly(3-hydroxybutyrate-co-3- hydroxyvalerate) by endophytic Bacillus cereus RCL 02

Sugarcane molasses, the by-product of sugar industry are rich in nutrients, growth factors and minerals and areefficiently utilized by the microorganisms for growth and production of primary as well as secondary metabolitesof commercial importance. In this communication, we report the utilization of sugarcane molasses as the solesource of carbon for the production of copolymers of polyhydroxyalkanoates (PHAs) with improved materialproperties. The endophytic bacterium Bacillus cereus RCL 02 (MCC 3436) produced 7.8 g/L of PHA whengrown in MS medium with 4% (w/v) sugarcane molasses under batch cultivation. Proton nuclear magneticresonance (1H NMR) analysis revealed that the copolymer so produced contain 12.4 mol% 3-hydroxyvalerate(3HV) along with 87.6 mol% 3-hydroxybutyrate (3HB). The copolyester, P(3HB-co-12.4 mol%-3HV)has been isolated and purified following standard solvent extraction method and partially characterized byFourier-transform infrared (FTIR), X-ray diffraction (XRD), thermogravimetric (TG) and differential scanningcalorimetric (DSC) analysis. The material and thermal properties of the copolyester so produced indicated itspotential for industrial application.

Hypoxic three-dimensional culture microenvironment promotes proliferation of bone marrow mesenchymal stem cells through HIF-1α signaling pathway / 中国胸心血管外科临床杂志

@#Objective To investigate the effects of hypoxic three-dimensional culture microenvironment on the proliferation of bone marrow mesenchymal stem cells and its mechanism. Methods P5 generation mouse bone marrow mesenchymal stem cells and P (3HB-co-4HB) were co-cultured under normoxic three-dimensional (20%) and hypoxic three-dimensional microenvironment (4%) respectively. After 24 hours, the proliferation of the two groups was determined by CCK-8 method. The expression of HIF-1α gene was detected by real-time quantitative PCR after 12 hours. Western blotting was used to detect the expression of HIF-1α protein after 24 hours. Results After 24 hours, the CCK-8 method showed that the OD value of the hypoxia group was significantly higher than that of the normoxia group (0.455±0.027 vs. 0.352±0.090, n=12, P<0.05). After 12 hours of hypoxic culture, the expression level of HIF-1α mRNA in the hypoxia group was significantly higher than that in the normoxia group (P<0.05). Compared with the normoxia group (0.47± 0.05), the relative expression level of HIF-1α protein in the hypoxia group (0.63±0.06) significantly increased in the Western blotting after 24 hours (n=3, P<0.05). Conclusion The hypoxic three-dimensional microenvironment can promote the proliferation of bone marrow mesenchymal stem cells, which may be related to the activation of HIF-1α signaling pathway.

Effect of reducing the activity of respiratory chain on biosynthesis of poly(3-hydroxybutyrate-co-lactate) in Escherichia coli / 生物工程学报

Poly(3-hydroxybutyrate-co-lactate) [P(3HB-co-LA)] belongs to the polyhydroxyalkanoates (PHA) family and possesses promising properties including biocompatibility and biodegradability. In this study, we directly synthesized P(3HB-co-LA) with glucose by introducing the β-ketothiolase and acetoacetyl-CoA reductase from Ralstonia eutropha, the engineered propionate CoA transferase from Clostridium propionicum and the engineered polyhydroxyalkanoate synthase from Pseudomonas fluorescens strain 2P24 into Escherichia coli. The polymer content was 83.9% (W/W), and the molar percentage of lactate reached 1.6%. On this basis, in order to accumulate lactate, we reduced the activity of respiratory chain by deleting the ubiX gene, which is involved in the synthesis of coenzyme Q8. Moreover, we removed the dld gene to avoid the conversion of lactate to pyruvate during the fermentation. With these manipulations, the molar percentage of lactate in the polymer was improved to 14.1%, with an 81.7% (W/W) of polymer content. The test results indicated that the strategy of reducing the activity of respiratory chain effectively increased the lactate units in the polymer, and it contributed a new approach to change the content of monomer components in the polymer.

Microbial production of poly (glycolate-co-lactate-co-3-hydroxybutyrate) from glucose and xylose by Escherichia coli / 生物工程学报

Escherichia coli was metabolically engineered to produce poly(glycolate-co-lactate-co-3-hydroxybutyrate) using glucose and xylose as carbon sources. The combinatorial biosynthetic route was constructed by the overexpression of a series of enzymes including D-tagatose 3-epimerase, L-fuculokinase, L-fuculose-phosphate aldolase, aldehyde dehydrogenase, propionyl-CoA transferase, β-ketothiolase, acetoacetyl-CoA reductase, and polyhydroxyalkanoate synthase. Overexpression of polyhydroxyalkanoate granule associated protein significantly improved biopolymer synthesis, and the recombinant strain reached 3.73 g/L cell dry weight with 38.72% (W/W) biopolymer content. A co-culture engineering strategy was developed to produce biopolymer from a mixture of glucose and xylose, achieving 4.01 g/L cell dry weight containing 21.54% (W/W) biopolymer. The results of this work offer an approach for simultaneously utilizing glucose and xylose and indicate the potential for future biopolymer production from lignocellulosic biomass.

Evaluation of poly(3-hydroxybutyrate) production by microbiota endogenous to oleaginous plants

Aims@#Microbiota endogenous to oleaginous plants have attracted special attention in recent years for their biotechnological potentials and applications including the production of biodegradable biopolyester poly(3- hydroxybutyrate) [P(3HB)] as an alternative to thermoplastics. The present study is aimed to screen the endophytic bacteria of selected oleaginous plants such as Arachis hypogaea L., Brassica napus L., Brassica nigra L., Helianthus annuus L., Ricinus communis L. and Sesamum indicum L. for the production of P(3HB). @*Methodology and results@#Bacteria endogenous to the oleaginous plants were isolated from surface sterilized healthy tissues following sterilization with 70% ethanol and 0.5% sodium hypochlorite and screened for P(3HB) production in mineral salts medium. Nile blue A staining method was used for detection of intracellular P(3HB), while the accumulated biopolyester was quantified spectrophotometrically following chemical conversion to chrotonic acid by treating with sulfuric acid. Five potent P(3HB) accumulating isolates have been selected and identified as Cellulosimicrobium cellulans AHS 01 (KX458038), Beijerinckia fluminensis AHR 02 (KX458039), Exiguobacterium acetylicum BNL 103 (KX458037), Bacillus toyonensis BNS 102 (KX458036) and Bacillus cereus RCL 02 (KX458035) based on morphological, physio-biochemical and 16S rDNA sequence analysis. These endogenously growing bacterial isolates accumulated intracellular biopolyester accounting 43-62% of their cell dry weight (CDW) when grown in mineral salts medium supplemented with yeast extract. Intracellular accumulation of P(3HB) by these isolates have also been confirmed by FTIR spectral analysis of lyophilized cell mass and 1HNMR spectra of the extracted polymer. @*Conclusion, significance and impact of study@#These findings, first of its kind point to exploration of endogenous bacterial communities of oil-producing plants as a potential bioresource for production of P(3HB) bioplastics in a sustainable manner.

Evaluation of injury degree of rat nephropathy model induced by doxorubicin based on metabolomics / 中草药

Objective To carry out the quantitative analysis of the injury degree of model rat of doxorubicin-induced nephropathy based on metabolomics. Methods 1H-NMR based metabolomics approach combined with multivariate statistical analysis were used to analyze rat serum samples from different doses and different times of doxorubicin administration and identify the progressive markers reflecting the progress degree of nephropathy. Moreover, the evaluation of injury degree of rat nephropathy model induced by doxorubicin was conducted according to the change degree of related markers. Results Nine potential biomarkers for pathological conditions were obtained such as 2-oxoisocaproate, isoleucine, leucine, valine, pyruvate, 3-hydroxybutyric acid, citric acid, creatinine, and carnitine, among which 2-oxoisocaproate and carnitine were in a dose-dependent manner, that is, the greater the dose of doxorubicin, the greater the variation of the endogenous metabolites, the more severe kidney injury, indicating that 2-oxoisocaproate and carnitine can be used as a progressive markers reflecting the process of kidney disease. Conclusion This study provides the diagnostic marker of nephropathy, and provides research methods and ideas for the study of other progressive diseases and the discovery of early diagnostic markers.

Determination of the Potential Genotoxic Impurities in Oxiracetam Raw Material by GC-MS / 中国药师

Objective:To establish a method for the determination of the potential genotoxic impurities [ methyl chloroacetate and ( R, S) 4-ethyl chloro-3-hydroxybutyrate ] in oxiracetam raw material .Methods:GC-MS was conducted , and the potential genotoxic impurities were extracted by ethyl acetate .The column was a VF-1701 ms capillary column (30 m ×0.25 mm, 0.25 μm) with pro-grammed temperature and the inlet temperature was 220 ℃.The column flow was 1.0 ml· min-1 and the purge flow was 5.0 ml· min-1 .The split injection was used and the split ratio was 5:1 .The carrier gas was high purity helium and the detector was a mass spectrometer detector .The ion source temperature was 230℃and the interface temperature was 230 ℃.The delay time of solvent was 4 min and the ionization mode was electron impact .The scanning ( detection ) method was selective ion monitoring , the electron energy was 70 eV, and the injection volume was 1.0 μl.Results:The separation between the impurities met the requirements .The concen-tration linear range was 50-400 ng· ml-1 (r≥0.9995).The recoveries were 89.7％-96.3％ (RSD=2.3％, n=9) and 91.0％-105.3％(RSD=4.4％, n=9), respectively.Conclusion:The method is simple, accurate, sensitive and rapid, and can be used for the determination of two potential genotoxic impurities in oxiracetam raw material .

A simple and efficient method for poly-3-hydroxybutyrate quantification in diazotrophic bacteria within 5 minutes using flow cytometry

The conventional method for quantification of polyhydroxyalkanoates based on whole-cell methanolysis and gas chromatography (GC) is laborious and time-consuming. In this work, a method based on flow cytometry of Nile red stained bacterial cells was established to quantify poly-3-hydroxybutyrate (PHB) production by the diazotrophic and plant-associated bacteria, Herbaspirillum seropedicae and Azospirillum brasilense. The method consists of three steps: i) cell permeabilization, ii) Nile red staining, and iii) analysis by flow cytometry. The method was optimized step-by-step and can be carried out in less than 5 min. The final results indicated a high correlation coefficient (R2=0.99) compared to a standard method based on methanolysis and GC. This method was successfully applied to the quantification of PHB in epiphytic bacteria isolated from rice roots.

Isolation and identification of bacteria and fungi growing spontaneously on polyhydroxyalkanoate pellets recovered by a new biological process

Aims: The study was carried out to isolate and identify the spontaneously growing populations of bacteria and fungi on the surface of biologically recovered polyhydroxyalkanoate (PHA) copolymer, poly(3-hydroxybutyrate-co-3- hydroxyhexanoate) [P(3HB-co-3HHx)]. Methodology and results: Large-scale PHA biosynthesis was carried out using 300 L fermenter and a biological methodology developed in our laboratory was utilized for PHA recovery. Using standard microbiological and molecular biology techniques the naturally growing microbial populations on the surface of biologically recovered PHA were identified. Scanning electron microscopy (SEM) analysis showed that the identified bacterial (Bacillus cereus and Burkholderia cepacia) and fungal isolates (Aspergillus niger, Byssochlamys nivea, Penicillium citrinum and Penicillium griseofulvum) were able to grow on and degrade the P(3HB-co-3HHx) copolymer. Conclusion, significance and impact of study: This is the first report on biologically recovered PHA pellet addressing the occurrence of microorganisms that grew spontaneously on it during storage under laboratory conditions. Fungi appeared to be dominant over bacteria in their ability to colonize the biologically recovered PHA.

Screening and Production of Biodegradable Polyester Poly(3-hydroxybutyrate) by Bacteria Endophytic to Brassica nigra L.

Aims: Poly(3-hydroxybutyrate) [P(3HB)], the microbially produced biodegradable thermoplastics has find wide range of applications in recent years. Development of low cost production strategies utilizing novel organisms is a crucial challenge. Present study is aimed to isolate and screen bacterial endophytes of Brassica nigra L. for the production of P(3HB). Place and Duration of Study: The experiments were performed in the Microbiology Laboratory, Department of Botany, University of Calcutta, Kolkata during 2012-2014. Methodology: Culturable bacterial endophytes were isolated from surface sterilized healthy tissues of B. nigra L. and screened for P(3HB) production in mineral salts medium. The chloroform extracted dried polymer was treated with H2SO4 and quantified spectrophotometrically at 235 nm. Results: About 78% of the bacterial endophytes recovered from surface sterilized B. nigra L. tissues showed different degrees of P(3HB) accumulation. Isolates (9) showing P(3HB) accumulation exceeding 10% of the cell dry weight (CDW) were characterized and tentatively identified as members of Bacillus, Pseudomonas, Xanthomonas, Alcaligenes and Acetobacter. The most potent isolate, BNL 06 identified as Bacillus pumilus BNL 06 (GenBank Accession No. KP202723), accumulated P(3HB) accounting 18% of CDW with an yield of 0.55 g/l. Finally the nature of the polymer was further confirmed by FTIR analysis. Conclusion: Exploration of the endophytic bacterial diversity of B. nigra L. have clearly revealed the potential of Bacillus pumilus BNL 06 for P(3HB) production as an alternative source of thermoplastics.

Mixed Cultures Fermentation for the Production of Poly- ß-hydroxybutyrate

Poly-ß-hydroxybutyrate (PHB) is a biodegradable intracellular microbial product produced by many bacteria and it is comparable to some of the petrochemical derived thermoplastics such as polypropylene. One of the main barriers for the commercial exploitation is the high cost of the substrate for the production of biopolymer. The utilization of mixed microbial cultures facilitates the use of complex substrates thereby reducing the cost of PHB production. In the present study, mixed culture systems were evaluated for PHB production. Bacillus firmus NII 0830 was used for the production of PHB since it accumulates a large amount of PHB and a second organism Lactobacillus delbrueckii NII 0925 was used to provide lactic acid. FTIR and 1H NMR analyses revealed that the PHB extracted from pure culture and mixed culture showed exact match to that of standard PHB. Biodegradation studies of the PHB blends showed 87% degradation. It was also found that a consortium of organisms degraded the films faster than a single organism.

Protective Effect of 3-hydroxybutyrate Derivate on the Apoptosis of PC12 / 医药导报

Objective To investigate the protective effect of 3-hydroxybutyrate derivate( methyl-3-hydroxybutyrate and ethyl-3-hydroxybutyrate)on the apoptosis of PC12 induced by FBS deficiency. Methods Methyl-3-hydroxybutyrate and ethyl-3-hydroxybutyrate were prepared by chemical degradation. PC12 cells were divided into different groups:medium with FBS as negative control,medium without FBS as positive control,medium with different concentrations of methyl-3-hydroxybutyrate or ethyl-3-hydroxybutyrate without FBS as sample groups. The shape and viability of cells in each group were analyzed by optical microscope and MTT. Results Compared with the negative control,cells in the positive control group demonstrated a large number of apoptosis,smaller and thinner morphology,and lower activity. However,the activity of cells was improved in the sample groups.Low concentration(0. 01 and 0. 001 mg·mL-1)of methyl-3-hydroxybutyrate and ethyl-3-hydroxybutyrate showed a protective effect on cell apoptosis,and 1 mg · mL-1 had the best protection effect. Conclusion High purity methyl-3-hydroxybutyrate and ethyl-3-hydroxybutyrate can be produced by chemical method,and both chemicals present good effect on protecting the PC12 from apoptosis.

Evaluation and improvement of anti-interference performance of D-3-hydroxybutyrate detection reagent / 国际检验医学杂志

Objective To evaluate the anti-interference performance of D-3-hydroxybutyrate (D3H ) reagent kit by using the NCCLS document EP7-A2 and to improve its anti-interference performance .Methods The anti-interference evaluation test of D3H kit was performed according to NCCLS document EP7-A2 and its anti-interference performance was improved by adding vitamin C oxidase .Results 342 mol/L free bilirubin ,342 mol/L conjugated bilirubin ,1 450 FTU chyle and 5 g/L hematoglobin had no inter-ference on the high concentration D3H detection ,0 .03 g/L vitamin C interfered with the low and high concentration D3H detection . The dosage-effect experiment results showed that vitamin C produced the linear positive interference effect on D 3H detection . Adding 2 500 U/L of vitamin C oxidase could antagonize the interference of vitamin C on detection .Conclusion Vitamin C can in-terfere with the D3H detection and adding vitamin C oxidase in reagent can antagonize its interference .

Preparation and cytocompatibility of novel porous calcium metaphosphate composite membranes / 中国组织工程研究

BACKGROUND:Porous poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/calcium metaphosphate composite membranes prepared previously is too thick and uneven in holes. OBJECTIVE:To prepare the thin even porous poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/calcium metaphosphate composite membrane, and to evaluate the cytocompatibility and differentiation capacity. METHODS:Porous and nonporous, thin and even poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/calcium metaphosphate composite membranes were prepared by phase separation method. Its thickness and weight loss rate were determined. Human bone marrow mesenchymal stem cel s were cocultured with porous and nonporous poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/calcium metaphosphate composite membranes for 7 days. Ultrastructure of composite membranes was observed under the scanning electron microscopy. Surface markers of the bone marrow mesenchymal stem cel s on the composite membranes were analyzed using flow cytometry. RESULTS AND CONCLUSION:The thickness of the porous and nonporous composite membranes was (0.041 ± 0.005) mm and (0.058±0.004) mm. Weight loss rates of porous and nonporous composite membranes were respectively 19.93%and 7.64%at 24 hours. Calcium metaphosphate particles were evenly distributed in porous and nonporous composite membrane. Cel s spread entirely, showing spindle shape. Calcium metaphosphate particles were evenly distributed in porous composite membrane. Pore in porous composite membranes was also uniformly distributed, and pore size was about 2-8μm. Cel s spread entirely, showing polygonal shape with multiple tentacles. The tentacles of some cel s entered into the scaffold. CD105, CD90, CD44, CD29 and CD73 expression was detected in porous and nonporous composite membranes. There was no significant difference in cel-positive rate. Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)/calcium metaphosphate composite membranes prepared in this study has good biocompatibility and could not promote cel differentiation.

Waste cooking oil as substrate for biosynthesis of poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate): Turning waste into a value-added product

Aims: Improper disposal of domestic wastes, such as waste cooking oil (WCO), contributes to the deterioration of the environment and may lead to health problems. In this study, we evaluated the potential of plant-based WCO as a carbon source for the commercial biosynthesis of the bio-plastics, poly(3-hydroxybutyrate) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate). The consumption of WCO for this purpose would mitigate their pollution of the environment at the same time. Methodology and Results: WCO collected from several cafeterias in USM was tested as the carbon source for polyhydroxyalkanoates (PHA) production. A selection of suitable nitrogen source was first conducted in order to obtain an acceptable number of dry cell weight (DCW) and PHA content. Urea was found to be a suitable nitrogen source for the two bacterial strains used in our study, Cupriavidus necator H16 and its transformed mutant, C. necator PHB¯4 harboring the PHA synthase gene of Aeromonas caviae (PHB¯4/pBBREE32d13). With WCO as the sole carbon source, C. necator H16 yielded a relatively good dry cell weight (DCW=25.4 g/L), with 71 wt% poly(3-hydroxybutyrate) P(3HB) content. In comparison, the DCW obtained with fresh cooking oil (FCO) was 24.8 g/L. The production of poly(3 hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] from WCO by the transformant C. necator PHB¯4 was comparable, yielding a DCW of 22.3 g/L and P(3HB-co-3HHx) content of 85 wt%. Lipase activities for both bacterial strains reached a maximum after 72 h of cultivation when time profile was conducted. Conclusion, significance and impact of study: The use of WCO as a carbon source in the biosynthesis of the bioplastic, PHA, turns a polluting domestic waste into a value-added biodegradable product. This renewable source material can thus be exploited for the low cost production of PHA.

Experimental study on biocompatibility between canine bone marrow stem cells and copolymers of poly-3-hydroxybutyrate-co-3-hydroxyvalerate / 中国病理生理杂志

AIM:To evaluate the biocompatibility between copolymers of poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV) and bone marrow stem cells (BMSCs). METHODS: Canine BMSCs were isolated and cultured. The cells in passage 3-4 were seeded onto the PHBV films and three-dimensional foams. The seeded cells were observed under inverted microscope for morphology and cell attachment onto the PHBV films at 1, 2 or 3 weeks after seeding. With 4% paraformaldehyde formalin and staining, the protein content in seeded cells was determined by bicinchoninic acid assay (BCA). The content of DNA was quantified using the Hoechst 33258 assay. RESULTS: Observation under inverted microscope showed that the PHBV fabric was fairly thickness, lucency is weak. Unser contrast phase microscope, PHBV fabric was uneasy to be observed. Most cells attached onto the PHBV films 2 h after seeding, and extended well and acquired a spindle fibrecyte-like morphology 3 d later. Moreover, on the three-dimensional foams, the seeded cells lay in micropores and grew tri-dimensionally. The conjunction of cells appeared about 1 week, and extended at 3 weeks, with a large amount of extracellular matrix around cells. The content of DNA and protein has no significant difference with control group. CONCLUSION: As a kind of tissue engineering material for BMSCs seeding, PHBV has an excellent biocompatibility.