Metabolic manipulation of Taxus canadensis for taxol production

1999 Spring.Includes bibliographic references (pages 198-212).In order to enhance taxol production in suspension cultures of Taxus sp., the regulation of biosynthetic pathways of the secondary metabolites have been investigated. The studies on elicitation and signal transduction showed interdependence of the ethylene and the methyl jasmonate (MJ) actions in affecting taxol biosynthetic reactions in Taxus canadensis C93AD. Reproducible results from independent experiments demonstrated complex changes in taxol and 10-deacetyl taxol, which increased in a manner proportional to MJ and ethylene concentrations. Based on the hypothesis of binding between biotic elicitors and receptor proteins on the plasma membrane, a mathematical model to explain the effects MJ and ethylene on the formation of taxol and other taxanes was developed. The inhibitory effect of MJ on taxol production, especially at concentrations greater than 100 μM, was observed and expressed in mathematical terms in the developed model. Taxol production was enhanced about 30 fold over unelicited conditions using 0.5% CO2, 15% O2 and 7 ppm ethylene with 200 μM MJ elicitation eight days after cell culture transfer. From precursor studies, improved taxol production can be obtained by supplementation of potential taxol side chain precursors and acetyl CoA together with MJ elicitation. The different profiles observed between taxol-related taxanes and baccatin Ill-related taxanes during elicitation suggest baccatin III may be either a degradation product of taxol or a product of 10-deacetyl baccatin III. The examination of profiles of taxol and 10-deacetyl taxol with different precursor supplements suggests a direct enzymatic reaction leading from 10-deacetyl taxol to taxol. A multivariable statistical method, Principal Component Analysis (PCA), was used for quality monitoring and fault detection of the experimental data. A correlation matrix demonstrated a positive relationship between ethylene and taxane concentration, strong positive linear relationships between MJ and taxol, 10-deacetyl taxol and baccatin III, and a negative relationship between MJ and 10-deacetyl baccatin III. Finally, extension of the stationary phase of the cell cycle in a semi-continuous culture with total cell recycle showed considerable improvement in productivity of taxol and other taxanes relative to batch culture

Reinforcement of Natural Rubber with Bacterial Cellulose via a Latex Aqueous Microdispersion Process

Natural rubber (NR) composites were reinforced with bacterial cellulose (BC) to improve mechanical and physical properties. The natural rubber bacterial cellulose (NRBC) composite films were prepared via a latex aqueous microdispersion process by a thorough mixing of BC slurry with natural rubber latex (NRL). The structural morphology and chemical and physical properties of NRBC composites were investigated. The hydrophilicity, opacity, and crystallinity of the NRBC composites were significantly enhanced because of the added BC. By loading BC at 80 wt.%, the mechanical properties, such as Young’s modulus and tensile strength, were 4,128.4 MPa and 75.1 MPa, respectively, which were approximately 2,580 times and 94 times those of pure NR films, respectively, whereas the elongation at break of was decreased to 0.04 of that of the NR film. Because of its high mechanical strength and thermal stability, the NRBC composites have potential uses as high mechanical strength rubber-based products and bioelastic packaging in many applications

Development of Arbuscular Mycorrhizal Fungi-Organic Fertilizer Pellets Encapsulated with Alginate Film

A novel formulation consisting of arbuscular mycorrhizal fungi (AMF) spores mixed with sterilized organic fertilizer (AMF-F) encapsulated by an insoluble calcium alginate film was developed to enhance AMF efficacy and stability. The hardness of the pellets increased from 7–8 N to approximately 80 N by increasing the alginate concentration of the coating film from 1 to 3%. The AMF spore germination rate for the AMF and AMF-F pellets coated with calcium alginate films depended on the alginate concentration. A 2% sodium alginate formulation for the coating films resulted in optimal AMF spore germination rates and mechanical properties for handling, transport, and stability. The inclusion of a sterilized organic fertilizer in the encapsulated AMF-F pellets considerably induced AMF mycelial growth and helped prolong the shelf life of the pellets. In soil, the AMF-F pellets encapsulated with alginate initially degraded faster than the alginate-encapsulated AMF pellets. However, both types of pellets were fully degraded within 30 days. It was demonstrated that AMF and AMF-F could promote colonization and provided resistance to drought stress in maize potted plants

Bacterial Cellulose-Alginate Membrane for Dehydration of Biodiesel-Methanol Mixtures

Pervaporation, a membrane-based technique, is taken into consideration in order to separate water from biodiesel-methanol mixtures. Several operational conditions in biodiesel production could cause water contamination into the reaction mixture, which can affect biodiesel production and quality. In this study, bacterial cellulose-alginate (BCA) nanocomposite film was applied as a selective membrane in order to separate water from biodiesel-methanol mixtures using pervaporation. For effective operation, factors that affected the performance in the pervaporation, such as concentration of water in the biodiesel-methanol mixtures and temperature of the process were investigated. It was demonstrated that, the BCA membrane has good potential for removing water from the biodiesel-methanol mixtures. Under a permeate pressure of 10 mmHg and 30°C, the BCA membrane could separate water from the mixture containing methyl ester (C10:0): methanol: water at a weight ratio of 42.3:52.7:5 with a total permeate flux of 148 g/(m2h) and a water selectivity of 332. The permeate was contained 94.5% w/w water and methyl ester was completely rejected by the BCA membrane. The increase of water concentration in biodiesel-methanol mixtures and the temperature rise resulted in an increase in the permeate flux but lowered the selectivity

Green Natural Rubber Composites Reinforced with Black/White Rice Husk Ashes: Effects of Reinforcing Agent on Film’s Mechanical and Dielectric Properties

Green natural rubber (NR) composites reinforced with black rice husk ash (BRHA)/white rice husk ash (WRHA), using alginate as a thickening and dispersing agent and crosslinking by CaCl2, was developed to improve mechanical, chemical and dielectric properties of NR-based films by using a latex aqueous microdispersion process. A maximum of 100 per hundred rubbers (phr) of rice husk ashes (RHAs) could be integrated in NR matrix without phase separation. Mechanical properties of the composite films were considerably enhanced, compared to the neat NR film. The composite films reinforced with WRHA demonstrated relatively better mechanical properties than those reinforced with BRHA, whereas the composites filled with BRHA demonstrated higher elongation at break. The crosslinking by CaCl2 improved the film tensile strength but lowered the film elasticity. The reinforcement strongly improved chemical resistance of the composite films in toluene. The films are biodegradable in soil, with weight loss of 7.6–18.3% of the initial dry weight after 3 months. Dielectric constant and dielectric loss factors of the composite films were enhanced with RHAs loading. According to the obtained properties, the composites offer potential for further development as stretchable conductive substrate or semiconducting polymer films for electronic applications

Lactic Acid Modified Natural Rubber–Bacterial Cellulose Composites

Green composite films of natural rubber/bacterial cellulose composites (NRBC) were prepared via a latex aqueous microdispersion process. The acid modified natural rubber/bacterial cellulose composites (ANRBC), in which lactic acid was used, showed significant improvement in mechanical properties, melting temperature, and high resistance to polar and non-polar solvents. The ANRBC films exhibited improved water resistance over that of BC and NRBC films, and possessed a higher resistance to non-polar solvents, such as toluene, than NR and NRBC films. The modification had a slight effect on the degradability of the composite films in soil. The NRBC and ANRBC films were biodegradable; the NRBC80 and ANRBC80 films were degraded completely within 3 months in soil. NRBC and ANRBC showed no antibacterial activity against Escherichia coli and Staphylococcus aureus and did not show cytotoxic effects on the HEK293 and HaCaT cell lines

Development and Characterization of Bacterial Cellulose Reinforced with Natural Rubber

Films of bacterial cellulose (BC) reinforced by natural rubber (NR) with remarkably high mechanical strength were developed by combining the prominent mechanical properties of multilayer BC nanofibrous structural networks and the high elastic hydrocarbon polymer of NR. BC pellicle was immersed in a diluted NR latex (NRL) suspension in the presence of ethanol aqueous solution. Effects of NRL concentrations (0.5%–10% dry rubber content, DRC) and immersion temperatures (30–70 °C) on the film characteristics were studied. It was revealed that the combination of nanocellulose fibrous networks and NR polymer provided a synergistic effect on the mechanical properties of NR–BC films. In comparison with BC films, the tensile strength and elongation at break of the NR–BC films were considerably improved ~4-fold. The NR–BC films also exhibited improved water resistance over that of BC films and possessed a high resistance to non-polar solvents such as toluene. NR–BC films were biodegradable and could be degraded completely within 5–6 weeks in soil

Multifunctional Cellulosic Natural Rubber and Silver Nanoparticle Films with Superior Chemical Resistance and Antibacterial Properties

Composite films of natural rubber/cellulose fiber/silver nanoparticle were synthesized in a green route via the latex solution process. Hybrid cellulose filler containing carboxymethyl cellulose and cellulose microfibers was used to facilitate facile and fast preparation and to improve mechanical strength to the composites, respectively. All the composites possessed a high tensile strength of ~120 MPa, a high heat resistance of nearly 300 °C, and more than 20% biodegradability in soil in two weeks. Chemical resistance and antibacterial activity of the composite was enhanced depending on sizes and concentrations of silver nanoparticles (AgNPs). The composites containing 0.033–0.1% w/w AgNPs retarded toluene uptake to less than 12% throughout 8 h, whereas the composite containing 0.067–0.1% w/w AgNPs exhibited excellent antibacterial activities against Escherichia coli and Staphylococcus aureus. In comparison, 50 nm-AgNPs presented higher antibacterial activities than 100 nm-AgNPs. In vitro cytotoxicity test assessed after incubation for 24 h and 48 h revealed that almost all AgNPs-composite films exhibited non/weak and moderate cytotoxicity, respectively, to HaCaT keratinocyte cells