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J B Gros - One of the best experts on this subject based on the ideXlab platform.
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Internal substrate concentrations during biotransformation of octanoic acid into 2-heptanone by spores ofPenicillium roquefortii
Journal of Industrial Microbiology, 1996Co-Authors: C Larroche, I Besson, J B GrosAbstract:Internal substrate concentrations were monitored during biotransformation of octanoic acid into 2-heptanone by spores of Penicillium roquefortii . The fatty acid rapidly enters the spores in its undissociated form, and a Collander-type relation shows that it strongly accumulates in the spore wall and membrane; this accumulation is reversible. The reaction takes place with cytoplasmic substrate concentrations that quickly fall to zero, and the process is limited by octanoic acid penetration into the cells. This entry is accompanied by proton efflux and involves an active transport process with a H^+-ATPase system that exhibits Michaelian behavior. The driving force is postulated to be ΔpH, which takes a value set by the initial substrate concentration through the stoichiometry of the H^+/octanoic acid exchange.
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behavior of spores of Penicillium roquefortii during fed batch bioconversion of octanoic acid into 2 heptanone
Biotechnology and Bioengineering, 1994Co-Authors: Christian Larroche, I Besson, J B GrosAbstract:The bioconversion of octanoic acid into 2-heptanone by spores of Penicillium roquefortii is performed using a fed-batch technique with pH control by addition of the liquid substrate itself. The early stage of this process takes place with a high bioconversion rate and high yield. These values then decrease as a result of germination and growth of the biocatalyst. An optimization strategy for the process would thus be to improve the characteristics of this first period, i.e., increase its duration and the reaction rate. An increase in duration is evidenced in two cases: (1) under oxygen limitation; and (2) when the spore content in the medium is less than 10[sup 7] spores/mL. These conditions give insufficient overall bioconversion rates; better optimization should be achieved without oxygen limitation and with high spore content. Characterization of the first period by material and bioenergetic balances suggests that an increase in the ethanol content of the medium, which acts as an energy source and a permeabilizer, and the use of a specific inhibitor of the Krebs cycle, may be a way to further improve the biocatalyst performance and stability.
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Characterization of water distribution in cell pellets using nonlabeled sodium thiosulfate as an interstitial space marker.
Biotechnology Progress, 1993Co-Authors: Christian Larroche, I Besson, Claude-gilles Dussap, Francois Bourrust, J B GrosAbstract:A procedure for determination of the intracellular water content of cells using a single, nonlabeled solute as an interstitial space marker is proposed. Sodium thiosulfate, which can be accurately assayed by a tritrimetric method, is found to be a good compound for this purpose. Cells are recovered both by filtration and centrifugation; the two techniques gave the same value for internal water, i.e., 650 mg of H2O/g of wet matter for Corynebacterium melassecola and 390 mg of H2O/g of wet matter for Penicillium roquefortii spores. The methodology of data handling, based on a regression technique, is also described. It allows one to obtain very reliable results and should be useful for any marker.
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Growth and sporulation behaviour of Penicillium roquefortii in solid substrate fermentation: effect of the hydric parameters of the medium
Applied Microbiology and Biotechnology, 1992Co-Authors: C Larroche, M. Theodore, J B GrosAbstract:Both growth and sporulation increase linearly according to the initial water content of the solid substrate when Penicillium roquefortii is cultivated on buckwheat seeds. This indicates that water is the limiting factor for fungal development since neither carbon nor nitrogen sources were exhausted during these experiments. This feature validates the concept of available water for fungal growth, defined as initial water content of substrate minus its residual water content when vegetative growth stops. An efficient methodology, based on drawing a regression line of mycelium dry weight production as a function of the initial water content of substrate is presented; it allows estimation of both available water and water content of mycelium. Results show that growth stops when the residual water in the substrate is close to 0.52 g H_2O/g initial dry matter, corresponding to a water activity (a_w) close to 0.96, and that the initial water content in mycelium is near 76%. Thus, both a_w and water content of the substrate have to be taken into account during the course of solid-state cultivations.
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characterization of the growth and sporulation behavior of Penicillium roquefortii in solid substrate fermentation by material and bioenergetic balances
Biotechnology and Bioengineering, 1992Co-Authors: Christian Larroche, J B GrosAbstract:: When Penicillium roquefortii is grown on two kinds of buckwheat, exhibiting a low [0.85 g water/g dry matter (DM), buckwheat A] and a high [1.5 g water/g initial dry matter (IDM), buckwheat B] water content, a marked difference in the mode of development of the fungus is observed. Material balances for buckwheat A show that growth does not stop because of nutrient exhaustion. Analysis of water balance shows that active growth proceeds with a permanent limitation by the turgor potential which disappears when the water activity of the substrate is close to 0.96, thus arresting growth. This limitation causes intensive water excretion from the system due to the lowering of the water activity of the substrate. The water content of the mycelium thus decreases from 79% at the beginning of the cultivation to 74% when the growth stops. This is linked to a substantial oxidative metabolism and a high sporulation efficiency, close to 0.85. The spores obtained have a low dry weight and a reduced nitrogen content. In the case of buckwheat B, the active growth is shown to stop because of available mineral nitrogen depletion. No significant decrease in the water activity of the substrate is found during the protein synthesis, and the turgor potential remains high at the end of this period. Culture proceeds with new wall synthesis; the sporulation efficiency remains high and the spores obtained exhibit a high dry weight and a high nitrogen content. The bioenergetic balances show that the P/O ratio varies with the kind of substrate used; its value is close to 1.56 for the low water medium and to 2.21 for the high one. The ATP yield Z is always close to 1, and fungal development occurs with limitations of both anabolism and catabolism on buckwheat B and only of anabolism and catabolism on buckwheat B and only of anabolism on buckwheat A.
Christian Larroche - One of the best experts on this subject based on the ideXlab platform.
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Special transformation processes using fungal spores and immobilized cells.
Advances in Biochemical Engineering \ Biotechnology, 1997Co-Authors: Christian Larroche, Jean-bernard GrosAbstract:Although many microbial processes have been described which are able to produce interesting aroma compounds, the number of industrial applications are limited. Reasons for this are in most cases low final product yield, low biotransformation rates, substrates and/or end-products inhibition, toxicity towards the microorganisms themselves and difficulties of recovery from the bioreaction mixture. This means that the development of specific catalysts and processes is an important challenge for researchers in this field. This review presents two special kinds of catalysts, fungal spores and immobilized cells, with emphasis on their production and on their use in the production of aroma compounds. The production of fungal spores by solid state fermentation is described in greater detail. In the second part, this review also offers examples of development of three production processes, the production of methyl ketones of spores of Penicillium roquefortii, the hydroxylation of beta-ionone by immobilized Aspergillus niger cells, and the production of alkyl pyrazines by bacteria in liquid and solid media. For each of these processes, the analysis of limiting steps-biological and/or physico-chemical-is presented and the significant role of process conditions to increase aroma yield is discussed.
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behavior of spores of Penicillium roquefortii during fed batch bioconversion of octanoic acid into 2 heptanone
Biotechnology and Bioengineering, 1994Co-Authors: Christian Larroche, I Besson, J B GrosAbstract:The bioconversion of octanoic acid into 2-heptanone by spores of Penicillium roquefortii is performed using a fed-batch technique with pH control by addition of the liquid substrate itself. The early stage of this process takes place with a high bioconversion rate and high yield. These values then decrease as a result of germination and growth of the biocatalyst. An optimization strategy for the process would thus be to improve the characteristics of this first period, i.e., increase its duration and the reaction rate. An increase in duration is evidenced in two cases: (1) under oxygen limitation; and (2) when the spore content in the medium is less than 10[sup 7] spores/mL. These conditions give insufficient overall bioconversion rates; better optimization should be achieved without oxygen limitation and with high spore content. Characterization of the first period by material and bioenergetic balances suggests that an increase in the ethanol content of the medium, which acts as an energy source and a permeabilizer, and the use of a specific inhibitor of the Krebs cycle, may be a way to further improve the biocatalyst performance and stability.
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Characterization of water distribution in cell pellets using nonlabeled sodium thiosulfate as an interstitial space marker.
Biotechnology Progress, 1993Co-Authors: Christian Larroche, I Besson, Claude-gilles Dussap, Francois Bourrust, J B GrosAbstract:A procedure for determination of the intracellular water content of cells using a single, nonlabeled solute as an interstitial space marker is proposed. Sodium thiosulfate, which can be accurately assayed by a tritrimetric method, is found to be a good compound for this purpose. Cells are recovered both by filtration and centrifugation; the two techniques gave the same value for internal water, i.e., 650 mg of H2O/g of wet matter for Corynebacterium melassecola and 390 mg of H2O/g of wet matter for Penicillium roquefortii spores. The methodology of data handling, based on a regression technique, is also described. It allows one to obtain very reliable results and should be useful for any marker.
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bioconversion of fatty acids into methyl ketones by spores of Penicillium roquefortii in a water organic solvent two phase system
Enzyme and Microbial Technology, 1992Co-Authors: Catherine Creuly, Christian Larroche, Jean-bernard GrosAbstract:Abstract C 5 –C 9 methyl ketones can be produced from the corresponding C 6 –C 10 fatty acids by spores of Penicillium roquefortii in a water—organic solvent, two-phase system operated using a fed-batch procedure carried out at constant substrate concentration. The organic phase consists of an industrial isoparaffin solvent which can be considered as tetradecane. The reaction is initially performed by resting spores, which have the best biocatalyst activity, and swelling of spores appears later. Optimization involves both increased initial reaction rate and late spore swelling. The biocatalyst is obtained by cultivation of the fungus by solid state fermentation on buckwheat seeds, and the simplest way to carry out bioconversion reactions is to use the whole sporulation medium without discarding the buckwheat grains. This method gives the best results, and 21 g l −1 2-pentanone, 73 g l −1 2-heptanone, and 57 g l −1 2-nonanone were recovered in this way.
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characterization of the growth and sporulation behavior of Penicillium roquefortii in solid substrate fermentation by material and bioenergetic balances
Biotechnology and Bioengineering, 1992Co-Authors: Christian Larroche, J B GrosAbstract:: When Penicillium roquefortii is grown on two kinds of buckwheat, exhibiting a low [0.85 g water/g dry matter (DM), buckwheat A] and a high [1.5 g water/g initial dry matter (IDM), buckwheat B] water content, a marked difference in the mode of development of the fungus is observed. Material balances for buckwheat A show that growth does not stop because of nutrient exhaustion. Analysis of water balance shows that active growth proceeds with a permanent limitation by the turgor potential which disappears when the water activity of the substrate is close to 0.96, thus arresting growth. This limitation causes intensive water excretion from the system due to the lowering of the water activity of the substrate. The water content of the mycelium thus decreases from 79% at the beginning of the cultivation to 74% when the growth stops. This is linked to a substantial oxidative metabolism and a high sporulation efficiency, close to 0.85. The spores obtained have a low dry weight and a reduced nitrogen content. In the case of buckwheat B, the active growth is shown to stop because of available mineral nitrogen depletion. No significant decrease in the water activity of the substrate is found during the protein synthesis, and the turgor potential remains high at the end of this period. Culture proceeds with new wall synthesis; the sporulation efficiency remains high and the spores obtained exhibit a high dry weight and a high nitrogen content. The bioenergetic balances show that the P/O ratio varies with the kind of substrate used; its value is close to 1.56 for the low water medium and to 2.21 for the high one. The ATP yield Z is always close to 1, and fungal development occurs with limitations of both anabolism and catabolism on buckwheat B and only of anabolism and catabolism on buckwheat B and only of anabolism on buckwheat A.
Jean-bernard Gros - One of the best experts on this subject based on the ideXlab platform.
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Special transformation processes using fungal spores and immobilized cells.
Advances in Biochemical Engineering \ Biotechnology, 1997Co-Authors: Christian Larroche, Jean-bernard GrosAbstract:Although many microbial processes have been described which are able to produce interesting aroma compounds, the number of industrial applications are limited. Reasons for this are in most cases low final product yield, low biotransformation rates, substrates and/or end-products inhibition, toxicity towards the microorganisms themselves and difficulties of recovery from the bioreaction mixture. This means that the development of specific catalysts and processes is an important challenge for researchers in this field. This review presents two special kinds of catalysts, fungal spores and immobilized cells, with emphasis on their production and on their use in the production of aroma compounds. The production of fungal spores by solid state fermentation is described in greater detail. In the second part, this review also offers examples of development of three production processes, the production of methyl ketones of spores of Penicillium roquefortii, the hydroxylation of beta-ionone by immobilized Aspergillus niger cells, and the production of alkyl pyrazines by bacteria in liquid and solid media. For each of these processes, the analysis of limiting steps-biological and/or physico-chemical-is presented and the significant role of process conditions to increase aroma yield is discussed.
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bioconversion of fatty acids into methyl ketones by spores of Penicillium roquefortii in a water organic solvent two phase system
Enzyme and Microbial Technology, 1992Co-Authors: Catherine Creuly, Christian Larroche, Jean-bernard GrosAbstract:Abstract C 5 –C 9 methyl ketones can be produced from the corresponding C 6 –C 10 fatty acids by spores of Penicillium roquefortii in a water—organic solvent, two-phase system operated using a fed-batch procedure carried out at constant substrate concentration. The organic phase consists of an industrial isoparaffin solvent which can be considered as tetradecane. The reaction is initially performed by resting spores, which have the best biocatalyst activity, and swelling of spores appears later. Optimization involves both increased initial reaction rate and late spore swelling. The biocatalyst is obtained by cultivation of the fungus by solid state fermentation on buckwheat seeds, and the simplest way to carry out bioconversion reactions is to use the whole sporulation medium without discarding the buckwheat grains. This method gives the best results, and 21 g l −1 2-pentanone, 73 g l −1 2-heptanone, and 57 g l −1 2-nonanone were recovered in this way.
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characterization of the behavior of Penicillium roquefortii in solid state cultivation on support by material balances
Journal of Fermentation and Bioengineering, 1992Co-Authors: Christian Larroche, Jean-bernard GrosAbstract:Abstract The growth and sporulation of Penicillium roquefortii were studied during solid state cultivations on support. The process involved the use of a porous material, pozzolano, impregnated and continuously fed at a small rate by a concentrated liquid nutritive medium. This system allowed the recovery of the total spores and biomass produced, due to the large average radius, close to 5 μm, of the pores available for the fungal development. The sporulation occurred in two waves, the first beginning when nitrogen limitation appeared. Nitrogen balances showed that this first wave occurred with a sporulation efficiency, defined as the ratio of the nitrogen incorporated into the conidia to the nitrogen assimilated by the mycelium, close to unity. The second wave gave spores that did not contain nitrogen. Carbon balances, established using the stoichiometric equations of the metabolisms that occurred, showed that this second sporulation wave arose in connection with assimilatory growth that took place together with mycelial lysis. This system allowed 7 × 10 8 active spores/g pozzolano to be obtained, corresponding to 4.7 × 10 11 spores/ l fermentor at 110h cultivation.
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2 heptanone production by spores of Penicillium roquefortii in a water organic solvent two phase system
Biocatalysis, 1992Co-Authors: Christian Larroche, Catherine Creuly, Jean-bernard GrosAbstract:The production of 2-heptanone from octanoic acid may be performed by free and entrapped spores of Penicillium roquefortii in a water-organic solvent two phase system.An industrial, isoparafflnic solvent, i.e. Hydrosol IP 230 O.S., which may be considered as tetradecane, is well suited for the process. Activities nearly double those achieved with aqueous systems are observed using an initial fatty acid content in the organic layer close to 100 mM and a ratio of the volume of the organic phase to the total volume of the medium of 0.88. The presence of the solvent allows a better recovery of the metabolite by lowering its activity coefficient.Fed-batch experiments performed in an aerated, stirred reactor show that the bioconversion may proceed in the two-phase system for at least 300 h. These conditions allow conversion of 750 mM (108 g · 1-1) fatty acid, and production of 600 mM (68.5 g · 1-1) 2-heptanone.
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A fed-batch technique for 2-heptanone production by spores of Penicillium roquefortii
Applied Microbiology and Biotechnology, 1990Co-Authors: Catherine Creuly, Christian Larroche, Jean-bernard GrosAbstract:A fed-batch technique for the production of 2-heptanone from octanoic acid by Ca-alginate/Eudragit RL-entrapped spores of Penicillium roquefortii is presented. It involves the use of a pH-stat apparatus, the increase in pH arising due to the reaction being overcome by direct substrate addition. When the reaction is performed at pH 5.5, no true constant rate period can be achieved due to a gradual buffering of the medium connected with a decrease in the catalytic activity of the spores. At pH 6.5 the system exhibits high stability and the reaction rate remains constant for at least 300 h with a value of 0.975 m M /h and a substrate concentration close to 4 m M . The process used may be very useful in the study of long-term behaviour of biocatalysts when the medium is not renewed and when the reaction involves an ionic compound and a neutral one.
Catherine Creuly - One of the best experts on this subject based on the ideXlab platform.
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bioconversion of fatty acids into methyl ketones by spores of Penicillium roquefortii in a water organic solvent two phase system
Enzyme and Microbial Technology, 1992Co-Authors: Catherine Creuly, Christian Larroche, Jean-bernard GrosAbstract:Abstract C 5 –C 9 methyl ketones can be produced from the corresponding C 6 –C 10 fatty acids by spores of Penicillium roquefortii in a water—organic solvent, two-phase system operated using a fed-batch procedure carried out at constant substrate concentration. The organic phase consists of an industrial isoparaffin solvent which can be considered as tetradecane. The reaction is initially performed by resting spores, which have the best biocatalyst activity, and swelling of spores appears later. Optimization involves both increased initial reaction rate and late spore swelling. The biocatalyst is obtained by cultivation of the fungus by solid state fermentation on buckwheat seeds, and the simplest way to carry out bioconversion reactions is to use the whole sporulation medium without discarding the buckwheat grains. This method gives the best results, and 21 g l −1 2-pentanone, 73 g l −1 2-heptanone, and 57 g l −1 2-nonanone were recovered in this way.
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2 heptanone production by spores of Penicillium roquefortii in a water organic solvent two phase system
Biocatalysis, 1992Co-Authors: Christian Larroche, Catherine Creuly, Jean-bernard GrosAbstract:The production of 2-heptanone from octanoic acid may be performed by free and entrapped spores of Penicillium roquefortii in a water-organic solvent two phase system.An industrial, isoparafflnic solvent, i.e. Hydrosol IP 230 O.S., which may be considered as tetradecane, is well suited for the process. Activities nearly double those achieved with aqueous systems are observed using an initial fatty acid content in the organic layer close to 100 mM and a ratio of the volume of the organic phase to the total volume of the medium of 0.88. The presence of the solvent allows a better recovery of the metabolite by lowering its activity coefficient.Fed-batch experiments performed in an aerated, stirred reactor show that the bioconversion may proceed in the two-phase system for at least 300 h. These conditions allow conversion of 750 mM (108 g · 1-1) fatty acid, and production of 600 mM (68.5 g · 1-1) 2-heptanone.
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A fed-batch technique for 2-heptanone production by spores of Penicillium roquefortii
Applied Microbiology and Biotechnology, 1990Co-Authors: Catherine Creuly, Christian Larroche, Jean-bernard GrosAbstract:A fed-batch technique for the production of 2-heptanone from octanoic acid by Ca-alginate/Eudragit RL-entrapped spores of Penicillium roquefortii is presented. It involves the use of a pH-stat apparatus, the increase in pH arising due to the reaction being overcome by direct substrate addition. When the reaction is performed at pH 5.5, no true constant rate period can be achieved due to a gradual buffering of the medium connected with a decrease in the catalytic activity of the spores. At pH 6.5 the system exhibits high stability and the reaction rate remains constant for at least 300 h with a value of 0.975 m M /h and a substrate concentration close to 4 m M . The process used may be very useful in the study of long-term behaviour of biocatalysts when the medium is not renewed and when the reaction involves an ionic compound and a neutral one.
C Larroche - One of the best experts on this subject based on the ideXlab platform.
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Internal substrate concentrations during biotransformation of octanoic acid into 2-heptanone by spores ofPenicillium roquefortii
Journal of Industrial Microbiology, 1996Co-Authors: C Larroche, I Besson, J B GrosAbstract:Internal substrate concentrations were monitored during biotransformation of octanoic acid into 2-heptanone by spores of Penicillium roquefortii . The fatty acid rapidly enters the spores in its undissociated form, and a Collander-type relation shows that it strongly accumulates in the spore wall and membrane; this accumulation is reversible. The reaction takes place with cytoplasmic substrate concentrations that quickly fall to zero, and the process is limited by octanoic acid penetration into the cells. This entry is accompanied by proton efflux and involves an active transport process with a H^+-ATPase system that exhibits Michaelian behavior. The driving force is postulated to be ΔpH, which takes a value set by the initial substrate concentration through the stoichiometry of the H^+/octanoic acid exchange.
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Growth and sporulation behaviour of Penicillium roquefortii in solid substrate fermentation: effect of the hydric parameters of the medium
Applied Microbiology and Biotechnology, 1992Co-Authors: C Larroche, M. Theodore, J B GrosAbstract:Both growth and sporulation increase linearly according to the initial water content of the solid substrate when Penicillium roquefortii is cultivated on buckwheat seeds. This indicates that water is the limiting factor for fungal development since neither carbon nor nitrogen sources were exhausted during these experiments. This feature validates the concept of available water for fungal growth, defined as initial water content of substrate minus its residual water content when vegetative growth stops. An efficient methodology, based on drawing a regression line of mycelium dry weight production as a function of the initial water content of substrate is presented; it allows estimation of both available water and water content of mycelium. Results show that growth stops when the residual water in the substrate is close to 0.52 g H_2O/g initial dry matter, corresponding to a water activity (a_w) close to 0.96, and that the initial water content in mycelium is near 76%. Thus, both a_w and water content of the substrate have to be taken into account during the course of solid-state cultivations.