The Experts below are selected from a list of 201 Experts worldwide ranked by ideXlab platform
Francois Fajula - One of the best experts on this subject based on the ideXlab platform.
-
the catalysis of the ruff oxidative degradation of Aldonic Acids by copper ii containing solids
Journal of Catalysis, 2002Co-Authors: Gwenaelle Hourdin, Alain Germain, Claude Moreau, Francois FajulaAbstract:The catalysis of the Ruff oxidative degradation of calcium D-gluconate to D-arabinose by aqueous diluted hydrogen peroxide was investigated using copper(II)-containing solids: zeolites and resins. Among zeolites, copper(II)-exchanged Y faujasite has given good results, similar to homogeneous copper catalysts. Only minute amounts of soluble copper were detected at the end of the reaction and the recovered solid was recycled twice without diminution of efficiency. However, it was not true heterogeneous catalysis because the chelating gluconate anion leached copper right from the beginning of the reaction. So, the catalysis occurred in solution but the metal precipitated again at the end of the reaction, when all the gluconate was consumed. Copper (II) iminodiacetic resin, in which the metal cation is more strongly bound than in the gluconate complex, was not active. This demonstrates that copper(II) must be in solution in order to be active.
-
the catalysis of the ruff oxidative degradation of Aldonic Acids by titanium containing zeolites
Catalysis Letters, 2000Co-Authors: Gwenaelle Hourdin, Alain Germain, Claude Moreau, Francois FajulaAbstract:Ti‐BEA and Ti‐FAU, obtained by post‐synthesis treatment, and TS‐1, obtained by direct hydrothermal synthesis, have been tested as catalysts for the Ruff oxidative degradation of calcium d‐gluconate to d‐arabinose using diluted hydrogen peroxide as oxidant. Only large‐pore zeolites Ti‐BEA and Ti‐FAU were found to be active. It was shown, in particular, that a very rapid leaching of titanium occurred and that the titanium species present in the solution were responsible for the catalytic activity observed.
-
The catalysis of the Ruff oxidative degradation of Aldonic Acids by titanium‐containing zeolites
Catalysis Letters, 2000Co-Authors: Gwenaelle Hourdin, Alain Germain, Claude Moreau, Francois FajulaAbstract:Ti‐BEA and Ti‐FAU, obtained by post‐synthesis treatment, and TS‐1, obtained by direct hydrothermal synthesis, have been tested as catalysts for the Ruff oxidative degradation of calcium d‐gluconate to d‐arabinose using diluted hydrogen peroxide as oxidant. Only large‐pore zeolites Ti‐BEA and Ti‐FAU were found to be active. It was shown, in particular, that a very rapid leaching of titanium occurred and that the titanium species present in the solution were responsible for the catalytic activity observed.
Gwenaelle Hourdin - One of the best experts on this subject based on the ideXlab platform.
-
the catalysis of the ruff oxidative degradation of Aldonic Acids by copper ii containing solids
Journal of Catalysis, 2002Co-Authors: Gwenaelle Hourdin, Alain Germain, Claude Moreau, Francois FajulaAbstract:The catalysis of the Ruff oxidative degradation of calcium D-gluconate to D-arabinose by aqueous diluted hydrogen peroxide was investigated using copper(II)-containing solids: zeolites and resins. Among zeolites, copper(II)-exchanged Y faujasite has given good results, similar to homogeneous copper catalysts. Only minute amounts of soluble copper were detected at the end of the reaction and the recovered solid was recycled twice without diminution of efficiency. However, it was not true heterogeneous catalysis because the chelating gluconate anion leached copper right from the beginning of the reaction. So, the catalysis occurred in solution but the metal precipitated again at the end of the reaction, when all the gluconate was consumed. Copper (II) iminodiacetic resin, in which the metal cation is more strongly bound than in the gluconate complex, was not active. This demonstrates that copper(II) must be in solution in order to be active.
-
the catalysis of the ruff oxidative degradation of Aldonic Acids by titanium containing zeolites
Catalysis Letters, 2000Co-Authors: Gwenaelle Hourdin, Alain Germain, Claude Moreau, Francois FajulaAbstract:Ti‐BEA and Ti‐FAU, obtained by post‐synthesis treatment, and TS‐1, obtained by direct hydrothermal synthesis, have been tested as catalysts for the Ruff oxidative degradation of calcium d‐gluconate to d‐arabinose using diluted hydrogen peroxide as oxidant. Only large‐pore zeolites Ti‐BEA and Ti‐FAU were found to be active. It was shown, in particular, that a very rapid leaching of titanium occurred and that the titanium species present in the solution were responsible for the catalytic activity observed.
-
The catalysis of the Ruff oxidative degradation of Aldonic Acids by titanium‐containing zeolites
Catalysis Letters, 2000Co-Authors: Gwenaelle Hourdin, Alain Germain, Claude Moreau, Francois FajulaAbstract:Ti‐BEA and Ti‐FAU, obtained by post‐synthesis treatment, and TS‐1, obtained by direct hydrothermal synthesis, have been tested as catalysts for the Ruff oxidative degradation of calcium d‐gluconate to d‐arabinose using diluted hydrogen peroxide as oxidant. Only large‐pore zeolites Ti‐BEA and Ti‐FAU were found to be active. It was shown, in particular, that a very rapid leaching of titanium occurred and that the titanium species present in the solution were responsible for the catalytic activity observed.
Fuping Lu - One of the best experts on this subject based on the ideXlab platform.
-
efficient production of sugar derived Aldonic Acids by pseudomonas fragi tccc11892
RSC Advances, 2018Co-Authors: Juanjuan Yang, Jianlin Wu, Fuping LuAbstract:Aldonic Acids are receiving increased interest due to their applications in nanotechnology, food, pharmaceutical and chemical industries. Microbes with aldose-oxidizing activity, rather than purified enzymes, are used for commercial production with limited success. Thus it is still very important to develop new processes using strains with more efficient and novel biocatalytic activities for the production of adonic Acids. In the present study, Pseudomonas fragi TCCC11892 was found to be an efficient producer of Aldonic Acids, with the production of galactonic and L-rhamnonic acid by P. fragi reported for the first time. The semi-continuous production of maltobionic acid and lactobionic acid was developed for P. fragi TCCC11892, achieving a yield of over 90 g L−1 for the first 7 cycles. The excellent performance of P. fragi in the production of lactobionic acid (119 g L−1) was also observed when using waste cheese whey as an inexpensive fermentation medium. Scaling up of the above process for production of Aldonic Acids with P. fragi TCCC11892 cells should facilitate their commercial applications.
Mauricio Moura Silveira - One of the best experts on this subject based on the ideXlab platform.
-
Assessment of different systems for the production of Aldonic Acids and sorbitol by calcium alginate-immobilized Zymomonas mobilis cells
Bioprocess and Biosystems Engineering, 2018Co-Authors: Analia Borges Folle, Victoria Maria Baschera, Luiza Tessaro Vivan, Sabrina Carra, Tomás Augusto Polidoro, Eloane Malvessi, Mauricio Moura SilveiraAbstract:Equimolar amounts of lactobionic acid and sorbitol may be obtained in a reaction catalyzed by the enzymes glucose–fructose oxidoreductase and glucono-δ-lactonase, which are found in the periplasm of Zymomonas mobilis . These reactions are generally conducted using immobilized bacterial cells, and the cell treatment and immobilization steps are costly and time-consuming. This study evaluated alternatives to simplify the preparation of calcium alginate-immobilized biocatalyst and its application in different operation modes and types of reactors. It was possible to eliminate cell permeabilization with cetyltrimethylammonium bromide, and the reticulation of Z. mobilis cells with glutaraldehyde sufficed to inhibit the fermentative metabolism of carbohydrates by the bacterium, with accumulation of bioconversion products. When the process was carried out in a mechanically stirred reactor in batch mode, 530 mmol L^− 1 of products were obtained in 24 h. The process was also tested in fed-batch mode so as to use of a larger amount of lactose, since it could not be used in the batch because of its low solubility in water. Under this condition, final products concentration reached 745 mmol L^− 1 within 42 h. Similar results were obtained for reactions conducted in a pneumatically stirred reactor in batch and fed-batch modes, proving the potential use of this process in several industrial settings.
-
Production of organic Acids by periplasmic enzymes present in free and immobilized cells of Zymomonas mobilis
Journal of Industrial Microbiology & Biotechnology, 2013Co-Authors: Eloane Malvessi, Sabrina Carra, Mauricio Moura Silveira, Flávia Cristina Pasquali, Denise Bizarro Kern, Marco Antônio Záchia AyubAbstract:In this work the periplasmic enzymatic complex glucose-fructose oxidoreductase (GFOR)/glucono-δ-lactonase (GL) of permeabilized free or immobilized cells of Zymomonas mobilis was evaluated for the bioconversion of mixtures of fructose and different aldoses into organic Acids. For all tested pairs of substrates with permeabilized free-cells, the best enzymatic activities were obtained in reactions with pH around 6.4 and temperatures ranging from 39 to 45 °C. Decreasing enzyme/substrate affinities were observed when fructose was in the mixture with glucose, maltose, galactose, and lactose, in this order. In bioconversion runs with 0.7 mol l^−1 of fructose and with aldose, with permeabilized free-cells of Z. mobilis , maximal concentrations of the respective Aldonic Acids of 0.64, 0.57, 0.51, and 0.51 mol l^−1 were achieved, with conversion yields of 95, 88, 78, and 78 %, respectively. Due to the important applications of lactobionic acid, the formation of this substance by the enzymatic GFOR/GL complex in Ca-alginate-immobilized cells was assessed. The highest GFOR/GL activities were found at pH 7.0–8.0 and temperatures of 47–50 °C. However, when a 24 h bioconversion run was carried out, it was observed that a combination of pH 6.4 and temperature of 47 °C led to the best results. In this case, despite the fact that Ca-alginate acts as a barrier for the diffusion of substrates and products, maximal lactobionic acid concentration, conversion yields and specific productivity similar to those obtained with permeabilized free-cells were achieved.
Eloane Malvessi - One of the best experts on this subject based on the ideXlab platform.
-
Assessment of different systems for the production of Aldonic Acids and sorbitol by calcium alginate-immobilized Zymomonas mobilis cells
Bioprocess and Biosystems Engineering, 2018Co-Authors: Analia Borges Folle, Victoria Maria Baschera, Luiza Tessaro Vivan, Sabrina Carra, Tomás Augusto Polidoro, Eloane Malvessi, Mauricio Moura SilveiraAbstract:Equimolar amounts of lactobionic acid and sorbitol may be obtained in a reaction catalyzed by the enzymes glucose–fructose oxidoreductase and glucono-δ-lactonase, which are found in the periplasm of Zymomonas mobilis . These reactions are generally conducted using immobilized bacterial cells, and the cell treatment and immobilization steps are costly and time-consuming. This study evaluated alternatives to simplify the preparation of calcium alginate-immobilized biocatalyst and its application in different operation modes and types of reactors. It was possible to eliminate cell permeabilization with cetyltrimethylammonium bromide, and the reticulation of Z. mobilis cells with glutaraldehyde sufficed to inhibit the fermentative metabolism of carbohydrates by the bacterium, with accumulation of bioconversion products. When the process was carried out in a mechanically stirred reactor in batch mode, 530 mmol L^− 1 of products were obtained in 24 h. The process was also tested in fed-batch mode so as to use of a larger amount of lactose, since it could not be used in the batch because of its low solubility in water. Under this condition, final products concentration reached 745 mmol L^− 1 within 42 h. Similar results were obtained for reactions conducted in a pneumatically stirred reactor in batch and fed-batch modes, proving the potential use of this process in several industrial settings.
-
Production of organic Acids by periplasmic enzymes present in free and immobilized cells of Zymomonas mobilis
Journal of Industrial Microbiology & Biotechnology, 2013Co-Authors: Eloane Malvessi, Sabrina Carra, Mauricio Moura Silveira, Flávia Cristina Pasquali, Denise Bizarro Kern, Marco Antônio Záchia AyubAbstract:In this work the periplasmic enzymatic complex glucose-fructose oxidoreductase (GFOR)/glucono-δ-lactonase (GL) of permeabilized free or immobilized cells of Zymomonas mobilis was evaluated for the bioconversion of mixtures of fructose and different aldoses into organic Acids. For all tested pairs of substrates with permeabilized free-cells, the best enzymatic activities were obtained in reactions with pH around 6.4 and temperatures ranging from 39 to 45 °C. Decreasing enzyme/substrate affinities were observed when fructose was in the mixture with glucose, maltose, galactose, and lactose, in this order. In bioconversion runs with 0.7 mol l^−1 of fructose and with aldose, with permeabilized free-cells of Z. mobilis , maximal concentrations of the respective Aldonic Acids of 0.64, 0.57, 0.51, and 0.51 mol l^−1 were achieved, with conversion yields of 95, 88, 78, and 78 %, respectively. Due to the important applications of lactobionic acid, the formation of this substance by the enzymatic GFOR/GL complex in Ca-alginate-immobilized cells was assessed. The highest GFOR/GL activities were found at pH 7.0–8.0 and temperatures of 47–50 °C. However, when a 24 h bioconversion run was carried out, it was observed that a combination of pH 6.4 and temperature of 47 °C led to the best results. In this case, despite the fact that Ca-alginate acts as a barrier for the diffusion of substrates and products, maximal lactobionic acid concentration, conversion yields and specific productivity similar to those obtained with permeabilized free-cells were achieved.
