Optimization of batch fermentation conditions for dextran production
TL;DR: The nutrient medium, temperature and initial pH conditions were optimised for batch dextran production in shake flask fermentations using a strain of Leuconostoc mesenteroides NRRL B 512 (F) and the optimal values of tested variables were found to be sucrose, yeast extract and K2HPO4.
Abstract: The nutrient medium (containing sucrose, yeast extract and K2HPO4), temperature and initial pH conditions were optimised for batch dextran production in shake flask fermentations using a strain of Leuconostoc mesenteroides NRRL B 512 (F). A 25−1 fractional factorial central composite experimental design was attempted. Multistage Monte Carlo optimization program was used to maximize the multiple regression equation obtained. The optimal values of tested variables for maximal dextran production were found to be: sucrose, 300 g/l; yeast extract, 10 g/l; K2HPO4, 30 g/l; temperature, 23°C and initial pH 8.3 with a predicted dextran yield of 154 g/l.
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TL;DR: The results demonstrated that this SPB1 biosurfactant exhibited an important antimicrobial activity against microorganisms with multidrug-resistant profiles, and was very effective against Staphylococcus aureus, Staphyllococcus xylosus, Enterococcus faecalis, Klebsiella pneumonia, and so forth.
Abstract: During the last years, several applications of biosurfactants with medical purposes have been reported. Biosurfactants are considered relevant molecules for applications in combating many diseases. However, their use is currently extremely limited due to their high cost in relation to that of chemical surfactants. Use of inexpensive substrates can drastically decrease its production cost. Here, twelve solid substrates were screened for the production of Bacillus subtilis SPB1 biosurfactant and the maximum yield was found with millet. A Plackett-Burman design was then used to evaluate the effects of five variables (temperature, moisture, initial pH, inoculum age, and inoculum size). Statistical analyses showed that temperature, inoculum age, and moisture content had significantly positive effect on SPB1 biosurfactant production. Their values were further optimized using a central composite design and a response surface methodology. The optimal conditions of temperature, inoculum age, and moisture content obtained under the conditions of study were 37°C, 14 h, and 88%, respectively. The evaluation of the antimicrobial activity of this compound was carried out against 11 bacteria and 8 fungi. The results demonstrated that this biosurfactant exhibited an important antimicrobial activity against microorganisms with multidrug-resistant profiles. Its activity was very effective against Staphylococcus aureus, Staphylococcus xylosus, Enterococcus faecalis, Klebsiella pneumonia, and so forth.
108 citations
Cites background from "Optimization of batch fermentation ..."
...When the magnitude of the t test value is large and the P value is small, this indicates that the corresponding coefficient is highly significant [30]....
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TL;DR: In this paper, the cumulative interactive effect of substrate, water concentration and time was studied in optimizing the hydrolysis of methyloleate using lipase from Chromobacterium viscosum immobilized on IRC-50.
Abstract: Hydrolysis of methyloleate was optimized using lipase from Chromobacterium viscosum immobilized on IRC-50. The optimization was studied by a statistical methodology using response surface methodology (RSM). The cumulative interactive effect of substrate, water concentration and time was studied in optimizing the hydrolysis of methyloleate. The interactive effect of substrate-time was found to be significant compared to substrate-water and time-water interactions. A well correlation was observed between the optimum values obtained from the response surface contour plots and from the quadratic regression model equation. The optimal values obtained for substrate, water and time were found to be in the experimental range chosen.
105 citations
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...where k is the number of test variables, (2) n0 center points (n0 ‡ 1) and ( 3 ) two axial points on the axis of each design variable at a distance of a (=2 k/4 , =2 for k = 4; =1.682 for...
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TL;DR: Enzymatic extraction of stevioside from Stevia rebaudiana leaves with cellulase, pectinase and hemicellulase, using various parameters, such as concentration of enzyme, incubation time and temperature, was optimised.
92 citations
TL;DR: In this article, a two-level Plackett-Burman design was employed first where 11 variables were studied for their influence on glucan production, Sucrose, peptone and yeast extract were the most significant variables improving glucan synthesis.
87 citations
TL;DR: Specialized encapsulation nanotechnologies will be discussed such as ionotropic gelation, complexation, the reverse microemulsion technique, cross-linking methods, emulsion-dependent methods, desolvation methods and self-assembly methods.
Abstract: For drug applications, nanoparticles, used as drug carriers, offer the advantage of controlled release, therapeutic impact and targeted delivery. In drug delivery applications, biodegradable polymers can be extracted from natural sources or prepared synthetically by polymerization. Natural polymers typically have varying compositions and physiochemical properties. As a result, methods which utilize natural polymers to encapsulate drugs are more varied and polymer dependent. The following polymers are discussed in this review article: alginate, chitosan, gelatin, albumin, gliadin, pullulan, and dextran. Specialized encapsulation nanotechnologies will be discussed such as ionotropic gelation, complexation, the reverse microemulsion technique, cross-linking methods, emulsion-dependent methods, desolvation methods and self-assembly methods. For each biopolymer an overview of the structure is presented with the corresponding encapsulation techniques. Understanding the structure of the biopolymer is important as to not only understand the rational for current encapsulation techniques but to continue to develop new encapsulation techniques in pursuit of the ideal drug carrier for application in therapeutic treatments.
86 citations
Cites background from "Optimization of batch fermentation ..."
...…bacteria excrete dextransucrase into their growth medium whereby the enzyme catalyzes conversion of sucrose into dextran by the following equation (Karthikeyan et al., 1996): n sucrose! ðGlucoseÞn þ n Fructose or Dextron Dextran is typically produced by batch fermentation of culture Leuconostoc…...
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...their growth medium whereby the enzyme catalyzes conversion of sucrose into dextran by the following equation (Karthikeyan et al., 1996):...
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01 Jan 2003
TL;DR: In this article, the authors present a survey of the properties of polymers and their application in the field of chemical engineering, including the following: Coextrusion, Injection Molding, Flexible Packaging, Fibers, Polymer-Clay, and Plasticizers.
Abstract: VOLUME 1. Acetylenic Polymers, Substituted. Acrylamide Polymers. Acrylic (and Methacrylic) Acid Polymers. Acrylic Ester Polymers. Acrylonitrile and Acrylonitrile Polymers. Acrylonitrile-Butadiene-Styrene Polymers. Additives. Adhesion. Adhesive Compounds. Aging, Physical. Alkyd Resins. Am,ino Resins and Plastics. Antifoaming Agents. Atomic Force Microscopy. Biotechnology Applications. Bloack Copolymers. Bloack Copolymers, Ternary Triblock. Blow Molding. Chitin and Chitosan. Chromatography, Affinity. Chromatography, HPLC. Chromatography, Size Exclusion. Coating Methods, Survey. Coatings. VOLUME 2 Coextrusion. Colorants. Coloring Processes. Composites, Fabrication. Conformation and Configuration. Critical Phase Polymerizations. Cyclohexanedimethanol Polyesters. Dendronized Polymers. Dental Applications. Diacethylene and Triacethylene Polymers. Elasticity, Rubber-Like. Electronic Packaging. Electrooptical Applications. Engineering, Thermoplastics, Overview. Enzymatic Polymerization. Ethylene Polymers, Chlorosulfonated. Ethylene Polymers, HDPE. Ethylene Polymers, LDPE. Ehtylene Polymers, LLDPE. Ethylene-Acrylic Elastomers. Ethylene-Norbornene Copolymers. Extrusion. Films, Orientation. Fluorocarbon Elastomers. Fractography. Fracture. Glass Transition. Hardness. Hydrogels. Hyperbranched Polymers. VOLUME 3 Injection Molding. Inorganic Polymers. Laser Light Scattering. Light-Emiting Diodes. Lignin. Liquid Crystalline Polymers, Main-Chain. Liquid Crystalline Thermosets. Mass Spectrometry. Membrane Technology. Methacrylic Ester Polymers. Micromechanical Properties. Modeling of Polymer Processing and Properties. Nanocomposites, Polymer-Clay. Packaging, Flexible. Perfluorinated Polymers, Perfluorinated Ethylene-Propylene Copolymers. Perfluorinated Polymers Polytetrafluoroethylene. Perfluorinated Polymers Tetrafluoroethylene-Ethylene Copolymers. Perfluorinated Polymers, Tetrafluoroethylene-Perfluorinated Copolymers. Perfluorinated Polymers. Tetrafluoroethylene-Perfluorovinyl Ether Copolymers. Phosgene. Phosphorus-Containing Polymers and Oligomers. Piezoelectric Polymers. Plasticizers. Poly(3-Hydroxyalkanoates). Poly(Trimethylene Terephthalate). Polyamides, Atomatic. Polyamides, Fibers. Polyamides, Plastics. Polycyanoacrylates. Polyesters, Fibers. Polyketones. Polynucleotides. Polysulfides. VOLUME 4 Polysulfones. Polyurethanes. Pressure-Sensitive Adhesive. Reinforcement. Release Agents. Shape-Memory Polymers. Single-Site Catalysis. Stabilization. Styrene-Butadiene Rubber (SBR). Styrene Polymers. Sulfur-Containing Polymers. Surface Properties. Syndiotactic Polystyrene. Vinyl Fluoride Polymers (PVF). Vinylidene Chloride Polymers. Vinylidene Fluoride Polymers. Viscoelasticity. Weathering.
3,190 citations
439 citations
TL;DR: Observation on factors affecting production of dextransucrase from Leuconostoc mesenteroides, strain NRRL B-512 and the possibility that more than one enzyme may be involved in the synthesis ofdextran is recognized.
Abstract: Present knowledge on the characteristics of dextransucrase and its mode of action is based primarily on the important investigations of Hehre (1941, 1946, 1951) and Hehre and Sugg (1942). Hitherto, a serious impediment to studies of this interesting enzyme has been the difficulty of procuring dextransucrase. Development of further knowledge about it would be greatly facilitated by the availability of culture liquors rich in dextransucrase. The rapid formation of dextransucrase in high yields has been reported in a preliminary note (Koepsell and Tsuchiya, 1952). The present report deals in greater detail with our observations on factors affecting production of dextransucrase from Leuconostoc mesenteroides, strain NRRL B-512.2 However, culture liquors high in activity have been obtained from a large number of the organisms tested. The dextran produced by strain NRRL B-512 in the conventional whole culture procedure contains about 95 per cent a-1,6-glucopyranosidic linkage. Although the non-1,6 linkages have been assumed to be of the a-1,4 type, definite proof on this point is lacking (Jeanes and Wilham, 1950). L. mesenteroides, strain NRRL B-512, or its substrains, is the organism principally used in investigations of clinical dextran in the United States. Although the term \"dextransucrase\" is used in the singular for convenience, the possibility that more than one enzyme may be involved in the synthesis of dextran is recognized.
152 citations
TL;DR: Mineral sources such as CaCO3 and KH2PO4 proved to be important factors influencing polysaccharide production and quality and the use of high carbon to nitrogen ratios in the defined medium resulted in a major increase in the broth consistency index.
83 citations