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 emerging broth showed higher yields of dextran presumably as a result of higher interface interactions between substrate and mycelia, and lignin in the medium is seen to be beneficial to both the final yield and specific rate of production.
15 citations
TL;DR: Using optimal conditions, the experimental value of α-l-arabinofuranosidase activity produced was very close to the model-predicted value, and the linear and quadric terms of the three variables had significant effects.
Abstract: This study is an application of an experimental design methodology for the optimization of the culture conditions of α-l-arabinofuranosidase production by Talaromyces thermophilus. Wheat bran and yeast extract were first selected as the best carbon and nitrogen sources, respectively, for enzyme production. A Plackett–Burman design was then used to evaluate the effects of eight variables. Statistical analyses showed that while pH had a negative effect on α-l-arabinofuranosidase production, wheat bran and MgSO4 had a significantly positive effect. The values of the latter three parameters were further optimised using a central composite design and a response surface methodology. The experimental results were fitted to a second-order polynomial model that yielded a determination coefficient of R
2 = 0.91. The statistical output showed that the linear and quadric terms of the three variables had significant effects. Using optimal conditions, the experimental value of α-l-arabinofuranosidase activity produced was very close to the model-predicted value. The optimal temperature and pH of enzyme activity were 55 °C and 7.0, respectively. This enzyme was very stable over a considerable pH range from 4 to 9. The crude enzyme of T. thermophilus rich in α-l-arabinofuranosidase was also used for saccharification of lignocellulosic materials and arabinose production.
15 citations
Cites background from "Optimization of batch fermentation ..."
...In fact, 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 (Karthikeyan et al. 1996)....
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TL;DR: The present investigation aimed to throw light on the effect of Bacillus subtilis SPB1 biosurfactant on the third larval instars of the Mediterranean flour moth, Ephestia kuehniella, under laboratory conditions and to improve the insecticidal activity of the SPB 1 biosURfactant against E. kueHniella larvae through optimisation of the pH of the biosurfacts solution and the incubation temperature.
Abstract: The present investigation aimed to throw light on the effect of Bacillus subtilis SPB1 biosurfactant on the third larval instars of the Mediterranean flour moth, Ephestia kuehniella, under laboratory conditions. The toxicity of this compound was investigated with emphasis on histopathological effects in the midgut of larvae. The tested dose levels showed strong histopathological disturbances in the midgut of this pest. The most frequently observed effects were cell vacuolisation, microvilli damage and epithelium cell contents passing into the midgut lumen. The present study was also extended to improve the insecticidal activity of the SPB1 biosurfactant against E. kuehniella larvae through optimisation of the pH of the biosurfactant solution and the incubation temperature using Central Composite Design. The experimental results were fitted to a second-order polynomial model that yielded a determination coefficient of R2 = 0.998. The optimal insecticidal activity conditions were found to be a temperature of 33.20°C and pH of 6.66. The predicted and observed responses were 200.4 ng mg−1 and 182.57 ng mg−1, respectively. In comparison to the original LC50 level, a 30% decrease was obtained.
13 citations
Cites background from "Optimization of batch fermentation ..."
...Indeed, 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 (Karthikeyan et al. 1996)....
[...]
01 Jan 2013
TL;DR: Present study reported statistical medium optimization for dextran and dextransucrase production for the strain comprising of Plackett-Burman and K2HPO4.
Abstract: On the basis of high enzyme activity a newly isolated strain was selected for dextran and dextransucrase production. Morphological, biochemical, and 16S rRNA sequencing analysis identified the strain as Lactobacillus acidophilus ST76480.01. It produced maximum dextran after 48 hours of incubation in the presence of sucrose as a carbon source, yeast extract and peptone as a nitrogen source at 30°C and pH 8.3. Present study reported statistical medium optimization for dextran and dextransucrase production for the strain comprising of Plackett-Burman. The increasing in sucrose concentration was significant for maximum dextran yield (4.24 mg/mL) and the highest dextransucrase activity (4.64 DSU/mL/hr) were obtained when 15% sucrose concentration was used while, the decreasing of K2HPO4 was significant for the highest dextransucrase activity (4.45 DSU/mL/hr) and (4.34 mg/mL) of dextran yield was obtained at (10 g/L) of K2HPO4.The structure of the polysaccharide dextran polymer was analyzed by 13
12 citations
Cites background from "Optimization of batch fermentation ..."
...Sucrose was an essential carbon source for dextransucrase and dextran synthesis by Leuconostoc species (Kartikeyan et al., 1996)....
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TL;DR: The results of this study indicated that the biomass generated from the laboratory experiments could be used, before discarding, to remove iron from leachate which is one of the main problems at the landfill sites.
Abstract: The adsorption capacity of wasted solids that contained dead fungal biomass (Phanerochaete chrysosporium) was studied to remove cadmium, copper, zinc and iron from synthetic water and leachate. The biomass was produced due to the experiments conducted for bioconversion of wastewater for lignin peroxydase production in the laboratory. In the screening experiments, the maximum cadmium (Cd) adsorption from synthetic water was 28.81% at 18 h. Meanwhile, adsorption of copper (Cu), zinc (Zn) and iron (Fe) reached maximum condition after 5 h with 41.29, 58.94 and 52.03% removal efficiency, respectively. However, the concentration of Cd, Cu and Zn was not detected in the leachate but Fe was found to be in high concentration (184 mg/L) in raw leachate collected from a municipal landfill site. Therefore, the effects of biomass dosage, contact time, pH and agitation speed were observed for optimal adsorption of iron from leachate. Optimum removal of iron from leachate was 45.56% in every 1 L of leachate after 1/50 dilutions. The optimized biomass dosage, contact time, pH and agitation speed were 750 mg/L, 4 h, pH 5, and 150 rpm, respectively. The results of this study indicated that the biomass generated from the laboratory experiments could be used, before discarding, to remove iron from leachate which is one of the main problems at the landfill sites.
11 citations
Cites background from "Optimization of batch fermentation ..."
...R-Sq = 92.8%, R-Sq(adj) = 84.3%, SS, sum of squares; DF, degree of freedom; MS, mean square. and smaller p-value indicates the high significance of the corresponding coefficient (Karthikeyan et al., 1996)....
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...and smaller p-value indicates the high significance of the corresponding coefficient (Karthikeyan et al., 1996)....
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...These significant factors are so important where they indicate limiting factors in the sense that even small variations in their values can alter the activity or removal of heavy metals to a considerable extent (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.
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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