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

Novel transparent nanocomposite films based on chitosan and bacterial cellulose

New nanocomposite films based on different chitosan matrices (two chitosans with different DPs and one water soluble derivative) and bacterial cellulose were prepared by a fully green procedure by casting a water based suspension of chitosan and bacterial cellulose nanofibrils. The films were characterized by several techniques, namely SEM, AFM, X-ray diffraction, TGA, tensile assays and visible spectroscopy. They were highly transparent, flexible and displayed better mechanical properties than the corresponding unfilled chitosan films. These new renewable nanocomposite materials also presented reasonable thermal stability and low O(2) permeability.FCT - SFRH/BD/41388/ 2007FCT - SFRH/BPD/38515/200

A review on the toxicology and dietetic role of bacterial cellulose

Bacterial cellulose (BC) is a biopolymer synthesized by certain acetic acid bacteria strains. The safety of BC regarding its potential use in food applications is here reviewed. The acute, sub-acute and subchronic oral toxicity assays showed that consumption of BC had no adverse effects in rats. Several studies demonstrated that BC is not genotoxic, did not induce chromosomal aberrations in CHO cells under both non-activating and metabolic activating conditions, is inactive in the in vitro Rat Primary Hepatocyte Unscheduled DNA Synthesis Assay, had no reproductive toxicity in mice and exerted no embryotoxicity and teratogenicity effects in rats. Several studies on the BC in biomedical applications further reinforces its safety: a primary eye and dermal irritation studies in the rabbit showed that BC was non-irritating. The inflammatory reaction to subcutaneously implanted BC has been evaluated in animal models and for different periods of time, demonstrating that BC is biocompatible and does not trigger a harsh inflammatory reaction. Altogether, and considering its longstanding history of human consumption in Asian countries, as well as its utilization in biomedical devices, it may be concluded that BC is safe for applications in food technology.FCT -Fuel Cell Technologies Program(NORTE-01-0145-FEDER-000004)info:eu-repo/semantics/publishedVersio

Bacterial cellulose production by Gluconacetobacter xylinus by employing alternative culture media

Bacterial cellulose (BC) is used in different fields as a biological material due to its unique properties. Despite there being many BC applications, there still remain many problems associated with bioprocess technology, such as increasing productivity and decreasing production cost. New technologies that use waste from the food industry as raw materials for culture media promote economic advantages because they reduce environmental pollution and stimulate new research for science sustainability. For this reason, BC production requires optimized conditions to increase its application. The main objective of this study was to evaluate BC production by Gluconacetobacter xylinus using industry waste, namely, rotten fruits and milk whey, as culture media. Furthermore, the structure of BC produced at different conditions was also determined. The culture media employed in this study were composed of rotten fruit collected from the disposal of free markets, milk whey from a local industrial disposal, and their combination, and Hestrin and Schramm media was used as standard culture media. Although all culture media studied produced BC, the highest BC yield60 mg/mLwas achieved with the rotten fruit culture. Thus, the results showed that rotten fruit can be used for BC production. This culture media can be considered as a profitable alternative to generate high-value products. In addition, it combines environmental concern with sustainable processes that can promote also the reduction of production cost.The authors would like to acknowledge the Brazil National Council of Technological and Scientific Development (CNPq, FAPESP, and CAPES), the financial support from FAPESP 2009/14897-7, and Fundacao para a Ciencia e a Tecnologia (FCT)/Portugal through the project PTDC/EBB-EBI/112170/2009 for the financial support and scholarship. Special thanks to Talita Almeida Vicentin for technical support

Natural carriers in bioremediation: a review

Bioremediation of contaminated groundwater or soil is currently the cheapest and the least harmful method of removing xenobiotics from the environment. Immobilization of microorganisms capable of degrading specific contaminants significantly promotes bioremediation processes, reduces their costs, and also allows for the multiple use of biocatalysts. Among the developed methods of immobilization, adsorption on the surface is the most common method in bioremediation, due to the simplicity of the procedure and its non-toxicity. The choice of carrier is an essential element for successful bioremediation. It is also important to consider the type of process (in situ or ex situ), type of pollution, and properties of immobilized microorganisms. For these reasons, the article summarizes recent scientific reports about the use of natural carriers in bioremediation, including efficiency, the impact of the carrier on microorganisms and contamination, and the nature of the conducted research

On the use of nanocellulose as reinforcement in polymer matrix composites

AbstractNanocellulose is often being regarded as the next generation renewable reinforcement for the production of high performance biocomposites. This feature article reviews the various nanocellulose reinforced polymer composites reported in literature and discusses the potential of nanocellulose as reinforcement for the production of renewable high performance polymer nanocomposites. The theoretical and experimentally determined tensile properties of nanocellulose are also reviewed. In addition to this, the reinforcing ability of BC and NFC is juxtaposed. In order to analyse the various cellulose-reinforced polymer nanocomposites reported in literature, Cox–Krenchel and rule-of-mixture models have been used to elucidate the potential of nanocellulose in composite applications. There may be potential for improvement since the tensile modulus and strength of most cellulose nanocomposites reported in literature scale linearly with the tensile modulus and strength of the cellulose nanopaper structures. Better dispersion of individual cellulose nanofibres in the polymer matrix may improve composite properties

Yeasts in sustainable bioethanol production: a review

Bioethanol has been identified as the mostly used biofuel worldwide since it significantly contributes to the reduction of crude oil consumption and environmental pollution. It can be produced from various types of feedstocks such as sucrose, starch, lignocellulosic and algal biomass through fermentation process by microorganisms. Compared to other types of microoganisms, yeasts especially Saccharomyces cerevisiae is the common microbes employed in ethanol production due to its high ethanol productivity, high ethanol tolerance and ability of fermenting wide range of sugars. However, there are some challenges in yeast fermentation which inhibit ethanol production such as high temperature, high ethanol concentration and the ability to ferment pentose sugars. Various types of yeast strains have been used in fermentation for ethanol production including hybrid, recombinant and wild-type yeasts. Yeasts can directly ferment simple sugars into ethanol while other type of feedstocks must be converted to fermentable sugars before it can be fermented to ethanol. The common processes involves in ethanol production are pretreatment, hydrolysis and fermentation. Production of bioethanol during fermentation depends on several factors such as temperature, sugar concentration, pH, fermentation time, agitation rate, and inoculum size. The efficiency and productivity of ethanol can be enhanced by immobilizing the yeast cells. This review highlights the different types of yeast strains, fermentation process, factors affecting bioethanol production and immobilization of yeasts for better bioethanol production