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Lee R. Lynd - One of the best experts on this subject based on the ideXlab platform.
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OPTIMIZATION OF AFFINITY DIGESTION FOR THE ISOLATION OF CELLULOSOMES FROM Clostridium thermocellum
Preparative Biochemistry & Biotechnology, 2013Co-Authors: Lois A. St Brice, Xiongjun Shao, Javier A. Izquierdo, Lee R. LyndAbstract:The affinity digestion process for cellulase purification consisting of binding to amorphous cellulose, and amorphous cellulose hydrolysis in the presence of dialysis (Morag et al., 1991), was optimized to obtain high activity recoveries and consistent protein recoveries in the isolation of Clostridium thermocellum cellulase. Experiments were conducted using crude supernatant prepared from C. thermocellum grown on either Avicel or cellobiose. While no difference was observed between Avicel-grown or cellobiose-grown cellulase in the adsorption step, differences were observed during the hydrolysis step. The optimal amorphous cellulose loading was found to be 3 mg amorphous cellulose per milligram supernatant protein. At this loading, 90–100% of activity in the crude supernatant was adsorbed. Twenty-four-hour incubation with the amorphous cellulose during the adsorption stage was found to result in maximal and stable adsorption of activity to the substrate. By fitting the adsorption data to the Langmuir mode...
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testing alternative kinetic models for utilization of crystalline cellulose Avicel by batch cultures of clostridium thermocellum
Biotechnology and Bioengineering, 2013Co-Authors: Evert K Holwerda, Lee R. LyndAbstract:Descriptive kinetics of batch cellulose (Avicel) and cellobiose fermentation by Clostridium thermocellum were examined with residual substrate and biosynthate concen- trations inferred based on elemental analysis. Biosynthate was formed in constant proportion to substrate consumption until substrate was exhausted for cellobiose fermentation, and until near the point of substrate exhaustion for cellulose fermentation. Cell yields (g pellet biosynthate carbon/ g substrate carbon) of 0.214 and 0.200 were obtained for cellulose and cellobiose, respectively. For cellulose fermenta- tion a sigmoidal curve fit was applied to substrate and biosynthate concentrations over time, which was then differentiated to calculate instantaneous rates of growth and substrate consumption. Three models were tested to describe the kinetics of Avicel utilization by C. thermocellum: (A) first order in cells, (B) first order in substrate, and (C) first order in cells and substrate, and second order overall. Models (A) and (B) have been proposed in the literature to describe cultures of cellulolytic microorganisms, whereas model (C) has not. Of the three models tested, model (c) provided by far the best fit to batch culture data. A second order rate constant equal to 0.735 L g C � 1 h � 1 was found for utilization of Avicel by C. thermocellum. Adding an endogenous metabolism term improved the descriptive quality of the model as substrate exhaustion was approached. Such rate constants may in the future find utility for describing and comparing cellulose fermentation involving other microbes and other substrates. Biotechnol. Bioeng. 2013;xxx: xx-xx.
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conversion for Avicel and afex pretreated corn stover by clostridium thermocellum and simultaneous saccharification and fermentation insights into microbial conversion of pretreated cellulosic biomass
Bioresource Technology, 2011Co-Authors: Xiongjun Shao, Lee R. Lynd, David A Hogsett, Anna Guseva, Venkatesh Balan, Bruce E DaleAbstract:In this study, efforts were taken to compare solubilization of Avicel and AFEX pretreated corn stover (AFEX CS) by SSF and Clostridium thermocellum fermentation, with an aim to gain insights into microbial conversion of pretreated cellulosic biomass. Solubilization rates for AFEX CS are comparable for the two systems while solubilization of Avicel is much faster by C. thermocellum. Initial catalyst loading impacts final cellulose conversion for SSF but not for C. thermocellum. Hydrolysis of the two substrates using cellfree C. thermocellum fermentation broth revealed much smaller difference in cellulose conversion than the difference observed for growing cultures. Tests on hemicellulose removal and particle size reduction for AFEX CS indicated that substrate accessibility is very important for enhanced solubilization by C. thermocellum.
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a kinetic model for simultaneous saccharification and fermentation of Avicel with saccharomyces cerevisiae
Biotechnology and Bioengineering, 2011Co-Authors: Eugene Van Rensburg, T M Harms, Lee R. LyndAbstract:This work describes a numerical model for predicting simultaneous saccharification and fermentation of Avicel, an insoluble crystalline cellulose polymer. Separate anoxic cultivations of 40 g/L glucose and 100 g/L Avicel were conducted to verify model predictions and obtain parameters to describe the reaction kinetics. Saccharification of Avicel was achieved with Trichoderma reesei cellulases from the enzyme preparation Spezyme CP with an enzyme loading of 10 FPU/g cellulose. Cultivations were supplemented with 50 IU/g cellulose of β-glucosidase from Novozym 188 to prevent product inhibition by cellobiose. Saccharomyces cerevisiae MH-1000 is a robust industrial strain and was used to ferment glucose to ethanol, glycerol, and carbon dioxide. The numerical model presented in this paper differs from previous models by separating the endoglucanase and exoglucanase enzyme kinetics and allowing for inhibitive site competition. Assuming all enzymes remain active and that each enzyme complex has a corresponding constant specific activity, the model is capable of predicting adsorbed enzyme concentrations with reasonable accuracy. Comparison of predicted values to experimental measurements indicated that the numerical model was capable of capturing the significant elements involved with cellulose conversion to ethanol. Biotechnol. Bioeng. 2011; 108:924–933. © 2010 Wiley Periodicals, Inc.
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kinetics of the extracellular cellulases of clostridium thermocellum acting on pretreated mixed hardwood and Avicel
Applied Microbiology and Biotechnology, 1994Co-Authors: Timothy D Bernardez, Kimberly A Lyford, Lee R. LyndAbstract:Initial hydrolysis rates were examined for mixed hardwood flour pretreated with 1% sulfuric acid for 9 s at 220 °C (PTW220) and Avicel. Linear rates were observed for fractional conversion relative to the theoretical up to 0.2 for PTW220 and 0.4 for Avicel. Initial rates were essentially unaffected by the presence of growth medium components over a range of pH values. Avicel-hydrolyzing activity was inhibited linearly by ethanol, with a 50% rate reduction at 8 wt.% ethanol. Rate saturation with either substrate or enzyme was observed in a manner qualitatively consistent with previously reported adsorption data. Although somewhat less reactive than Avicel at very low enzyme loadings, much higher reaction rates were observed for PTW220 at moderate and high enzyme loading because of its higher capacity to bind cellulase. At equal subtrate concentrations (as potential glucose) and fractional substrate coverage of 0.09, the initial rate of pretreated wood hydrolysis exceeded that of Avicel by 15-fold. For fractional substrate coverage values up to 0.09 (the maximum value achieved for PTW220), the initial rate was proportional to adsorbed enzyme for PTW220. However, the rate per adsorbed enzyme declined sharply with increasing fractional coverage for Avicel hydrolysis.
Antonio Aprigio Da Silva Curvelo - One of the best experts on this subject based on the ideXlab platform.
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characterization of depolymerized residues from extremely low acid hydrolysis ela of sugarcane bagasse cellulose effects of degree of polymerization crystallinity and crystallite size on thermal decomposition
Industrial Crops and Products, 2012Co-Authors: Leandro Vinicius Alves Gurgel, Karen Marabezi, Luiz Antonio Ramos, Antonio Aprigio Da Silva CurveloAbstract:Sugarcane bagasse cellulose was subjected to the extremely low acid (ELA) hydrolysis in 0.07% H2SO4 at 190, 210 and 225 ◦ C for various times. The cellulose residues from this process were characterized by TGA, XRD, GPC, FTIR and SEM. A kinetic study of thermal decomposition of the residues was also carried out, using the ASTM and Kissinger methods. The thermal studies revealed that residues of cellulose hydrolyzed at 190, 210 and 225 ◦C for 80, 40 and 8 min have initial decomposition temperature and activation energy for the main decomposition step similar to those of Avicel PH-101. XRD studies confirmed this finding by showing that these cellulose residues are similar to Avicel in crystallinity index and crystallite size in relation to the 110 and 200 planes. FTIR spectra revealed no significant changes in the cellulose chemical structure and analysis of SEM micrographs demonstrated that the particle size of the cellulose residues hydrolyzed at 190 and 210 ◦C were similar to that of Avicel.
P Humbertdroz - One of the best experts on this subject based on the ideXlab platform.
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morphological packing flow and tableting properties of new Avicel types
Drug Development and Industrial Pharmacy, 1995Co-Authors: Eric Doelker, Danielle Massuelle, Fabienne Veuillez, P HumbertdrozAbstract:AbstractThe six Avicel products designed for compression - the classical grades PH-105, PH-103, PH-101 and PH-102, and the new Avicels PH-112 and PH-200 - have been submitted to a comparative investigation for both their basic and tableting properties. According to the manufacturer all these products differ by their nominal particle size and moisture content.Basic properties of the powders were first determined, namely moisture content (loss on drying and Karl Fischer titration), particle size and shape (sieving and image analysis), densities (true bulk and tap densities, Hausner ratio) and flow properties (vibratory hopper technique).As tableting properties, the compactibility of the powders and the effect of adding a hydrophobic lubricant (0.5% magnesium stearate) on the compact strength were evaluated by preparing compacts at a given applied pressure using a hydraulic press. Weight and dimensional variations were assessed by preparing tablets at a target crushing strength of 70 Newtons on a high speed ...
Meisa Handini Tampara - One of the best experts on this subject based on the ideXlab platform.
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improvement of gliclazide s dissolution rate by using surface solid dispersion with Avicel ph 101
International Journal of Pharmacy and Pharmaceutical Sciences, 2014Co-Authors: Jessie Sofia Pamudji, Saleh Wikarsa, Meisa Handini TamparaAbstract:Objective: The aim of this study was to improve the dissolution rate of gliclazide by developing a surface solid dispersion (SSD) with Avicel PH 101 as a carrier. Methods: S olid dispersions of gliclazide were prepared, with various ratios of gliclazide and Avicel PH 101, using the solvent evaporation method. Evaluations of the dissolution rate for each ratio were carried out in order to find the optimal formula. The physical characteristic of solid dispersions was evaluated using Fourier transform infrared (FTIR), powder X-ray diffractometry (PXRD), and Scanning Electron Microscopy (SEM). The pure gliclazide powder and its solid dispersions were then blended with excipients and compressed into tablets by using the direct compression method. Results: The optimum solid dispersion, which consists of gliclazide and Avicel PH 101 at ratio 1:5, showed the highest dissolution rate. The infrared spectrum of the solid dispersion showed that the spectrum was a combination of gliclazide and Avicel PH 101, and that there is no differences between the spectrum of the solid dispersion and its physical mixture. The diffractogram of PXRD showed that there was a change in the gliclazide’s crystalline state in solid dispersion compared to its physical mixture. Whereas, SEM characterization indicated that the solid dispersion had an adsorption of gliclazide particles on the surface of Avicel PH 101 particles in the form of small particles. Conclusion: The preparation of surface solid dispersion with Avicel PH 101 can be used to increase the dissolution rate of gliclazide. The compression process did not alter the dissolution profile of gliclazide solid dispersion.
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improvement of gliclazide s dissolution rate by using surface solid dispersion with Avicel ph 101 original article
2014Co-Authors: Jessie Sofia Pamudji, Saleh Wikarsa, Meisa Handini TamparaAbstract:Objective: The aim of this study was to improve the dissolution rate of gliclazide by developing a surface solid dispersion (SSD) with Avicel PH 101 as a carrier. Methods: Solid dispersions of gliclazide were prepared, with various ratios of gliclazide and Avicel PH 101, using the solvent evaporation method. Evaluations of the dissolution rate for each ratio were carried out in order to find the optimal formula. The physical characteristic of solid dispersions was evaluated using Fourier transform infrared (FTIR), powder X-ray diffractometry (PXRD), and Scanning Electron Microscopy (SEM). The pure gliclazide powder and its solid dispersions were then blended with excipients and compressed into tablets by using the direct compression method. Results: The optimum solid dispersion, which consists of gliclazide and Avicel PH 101 at ratio 1:5, showed the highest dissolution rate. The infrared spectrum of the solid dispersion showed that the spectrum was a combination of gliclazide and Avicel PH 101, and that there is no differences between the spectrum of the solid dispersion and its physical mixture. The diffractogram of PXRD showed that there was a change in the gliclazide’s crystalline state in solid dispersion compared to its physical mixture. Whereas, SEM characterization indicated that the solid dispersion had an adsorption of gliclazide particles on the surface of Avicel PH 101 particles in the form of small particles. Conclusion: The preparation of surface solid dispersion with Avicel PH 101 can be used to increase the dissolution rate of gliclazide. The compression process did not alter the dissolution profile of gliclazide solid dispersion.
Angi Nadya Bestari - One of the best experts on this subject based on the ideXlab platform.
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optimization formula tablet extract of bengkuang pachyrrhizus erosus variation Avicel ph 101 and crospovidone
Current Opinion in Organ Transplantation, 2018Co-Authors: Rizki Kharisma, Ika Puspita Sari, Angi Nadya BestariAbstract:Bengkuang ( Pachyrrhizus erosus ) contains daidzein which is pro-estrogenic compound, suppressing bone restoration by directing mechanism in bone estrogen receptor. Bengkuang can be developed into a useful source of phytoestrogens as a supplement in menopausal women. This study aims to determine the stability and influence of Avicel® PH 101 and crospovidone on granular flow properties and physical properties of Bengkuang tuber extract. Bengkuang tuber extracts were made into tablet preparations by wet granulation method. Variation of crospovidone composition was between 2-5%, while Avicel® PH 101 was between 38.86 to 41.86%. The tablet formulation is optimized using the Simplex Lattice Design method. The results show that the addition of Avicel® PH 101 can improve the index of determination, water absorption, moisture content, hardness, time of disintegration, and friability of the tablet, as well as crospovidone addition. Avicel® PH 101 and crospovidone interactions increase water content, decrease hardness, and tablet friability. The optimum tablet formula consists of composition of 293 mg of Avicel® PH 101 and 14 mg of crospovidone per tablet. Testing of optimum formula results with SLD method did not differ significantly to the response of the compression index, hardness and friability of the tablet. The tablet was stable at room temperature (30oC ± 2 oC) for four weeks.
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the formulation of pacing costus speciosus extract tablet by using Avicel ph 200 as filler binder and amylum as disintegration agent
INDONESIAN JOURNAL OF PHARMACY, 2018Co-Authors: Damayanti Damayanti, Ika Puspita Sari, Angi Nadya Bestari, T Saifullah N Sulaiman, Irfan Muris SetiawanAbstract:Pacing ( Costus speciosus ) is an herbaceous plant that is native to Indonesia and it can be used as a male contraceptive due to spermatogenesis inhibition. The purpose of this study is to find out the composition of optimum Avicel PH 200 ® as the filler-binder and amylum as the disintegration agent and to find out the variations on physical properties of the powder and tablet. The tablets were made by directly compression in 8 runs based on Simplex Lattice Design (SLD) from Design Expert 7.1.5, in which the test on physical properties of powder includes tapping index, water absorption, and moisture content, as well as on the physical properties of tablet, including hardness, friability, and disintegration time. The results showed that the variation in the composition between Avicel ® PH 200 as the filler-binder and amylum as the disintegration agent had a significant effect on the friability of Costus speciosus (CS) extract tablet, in which the combination of both materials can increase the friability of the tablet. The optimum formula of CS tablet had a composition of Avicel ® PH 200 by 462,5 mg and amylum by 37,5 mg contained in each tablet.
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The Formulation of Pacing (Costus speciosus) Extract Tablet by Using Avicel®Ph 200 As Filler-Binder and Amylum As Disintegration Agent
INDONESIAN JOURNAL OF PHARMACY, 2018Co-Authors: Damayanti Damayanti, Ika Puspita Sari, Angi Nadya Bestari, T.n. Saifullah Sulaiman, Irfan Muris SetiawanAbstract:Pacing ( Costus speciosus ) is an herbaceous plant that is native to Indonesia and it can be used as a male contraceptive due to spermatogenesis inhibition. The purpose of this study is to find out the composition of optimum Avicel PH 200 ® as the filler-binder and amylum as the disintegration agent and to find out the variations on physical properties of the powder and tablet. The tablets were made by directly compression in 8 runs based on Simplex Lattice Design (SLD) from Design Expert 7.1.5, in which the test on physical properties of powder includes tapping index, water absorption, and moisture content, as well as on the physical properties of tablet, including hardness, friability, and disintegration time. The results showed that the variation in the composition between Avicel ® PH 200 as the filler-binder and amylum as the disintegration agent had a significant effect on the friability of Costus speciosus (CS) extract tablet, in which the combination of both materials can increase the friability of the tablet. The optimum formula of CS tablet had a composition of Avicel ® PH 200 by 462,5 mg and amylum by 37,5 mg contained in each tablet.