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J M Navarro - One of the best experts on this subject based on the ideXlab platform.
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effects of lignocellulose degradation products on ethanol fermentations of glucose and xylose by saccharomyces cerevisiae zymomonas mobilis pichia stipitis and Candida Shehatae
Enzyme and Microbial Technology, 1996Co-Authors: J P Delgenes, R Moletta, J M NavarroAbstract:The inhibitory effects of six lignocellulose degradation products on glucose fermentation by Saccharomyces cerevisiae and Zymomonas mobilis on xylose fermentation by Pichia stipitis and Candida Shehatae were studied in batch cultures. Toxic compounds were added in varying concentrations and subsequent inhibitions on growth and ethanol production were quantified. Vanillin was shown to be a strong inhibitor of both growth and ethanol production by xylose fermenting yeasts and S. cerevisiae when it was added to the culture media at a concentration of 1 g l−1. Fermentative activities of Z. mobilis were greatly sensitive to the presence of hydroxybenzaldehyde (0.5 g l−1). Analysis of culture media extracts showed that some of the inhibitors, particularly vanillin and furaldehyde, could be assimilated by the tested microbial strains which resulted in the partial recovery in both growth and ethanol production processes on prolonged incubation.
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Alcoholic fermentation of glucose and xylose by Pichia stipitis, Candida Shehatae, Saccharomyces cerevisiae and Zymomonas mobilis: oxygen requirement as a key factor
Applied Microbiology and Biotechnology, 1991Co-Authors: J. M. Laplace, J P Delgenes, R Moletta, J M NavarroAbstract:To investigate simultaneous alcoholic fermentation of glucose and xylose derived from lignocellulosic material by separate or co-culture processes, the effect of oxygen transfer rate (OTR) on the fermentation of 50 g/l xylose by Pichia stipitis NRRL Y 7124 and Candida Shehatae ATCC 22984, and the fermentation of 50 g/l glucose by Saccharomyces cerevisiae CBS 1200 and Zymomonas mobilis ATCC 10988 was carried out in batch cultures. The kinetic parameters of the xylose-fermenting yeasts were greatly dependent on the OTR. The optimum OTR values were found to be 3.9 and 1.75 mmol·1^−1·h^−1 for C. Shehatae and P. stipitis , respectively. By contrast the fermentative parameters of S. cerevisiae were poorly affected by the OTR range tested (0.0–3.5 mmol·l^−1·h^−1) Under these conditions the ethanol yields ranged from 0.41 g·g^−1 to 0.45 g·g^−1 and the specific ethanol productivity was around 0.70 g·g^−1·h^−1. Z. mobilis gave the highest fermentative performance under strictly anaerobic conditions (medium continually flushed with nitrogen): under these conditions, the ethanol yield was 0.43 g·g^−1 and the average specific ethanol productivity was 2.3 g·g^−1·h^−1. Process considerations in relation to the effect of OTR on the fermentative performance of the tested strains are discussed.
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Combined alcoholic fermentation of D-xylose and D-glucose by four selected microbial strains: process considerations in relation to ethanol tolerance.
Biotechnology Letters, 1991Co-Authors: J. M. Laplace, J P Delgenes, René Moletta, J M NavarroAbstract:As components of combined fermentation of both glucose and xylose to ethanol by separated or coculture processes, the effects of initial sugar concentrations on the fermentative performances ofPichia stipitis Y7124,Candida Shehatae ATCC 22984,Saccharomyces cerevisiae CBS1200 andZymomonas mobilis ATCC10988 were investigated. From the characteristics of sugar and produced ethanol tolerances the most suitable microorganisms for the achievement of glucose and xylose fermentations have been selected with respect to different fermentation schemes.
Guy-alain Junter - One of the best experts on this subject based on the ideXlab platform.
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Long-term incomplete xylose fermentation, after glucose exhaustion, with Candida Shehatae co-immobilized with Saccharomyces cerevisiae.
Microbiological research, 2006Co-Authors: Thierry Lebeau, Thierry Jouenne, Guy-alain JunterAbstract:Saccharomyces cerevisiae and Candida Shehatae were co-immobilized in an agar sheet which was introduced in an original two-chambered bioreactor asymmetrically fed in a batch mode with a mixture of glucose and xylose in a ratio of 35:15. The two sugars were consumed simultaneously. All glucose was fermented but only 20% of xylose. After incubation, yeast cells recovered from different areas of the agar sheet (close to, called Hi, and distant from, called Ho, the substrate chamber) were cultured as suspended cells in fresh culture medium provided with xylose or the sugar mixture. Xylose utilization by gel released Hi yeasts was significantly delayed compared to the Ho culture. Ethanol consumption by Hi yeasts in the two-substrate medium occurred after glucose exhaustion despite the presence of xylose. The waste medium resulting from incubation of the immobilized-cell structure inhibited xylose utilization by C. Shehatae. Our results suggested that batch fermentation most probably favoured this incomplete xylose fermentation.
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Continuous alcoholic fermentation of glucose/xylose mixtures by co-immobilized Saccharomyces cerevisiae and Candida Shehatae
Applied microbiology and biotechnology, 1998Co-Authors: Thierry Lebeau, Thierry Jouenne, Guy-alain JunterAbstract:Viable Saccharomyces cerevisiae and Candida Shehatae cells were co-immobilized in a composite agar layer/microporous membrane structure. This immobilized-cell structure was placed in a vertical position between the two halves of a double-chambered, stainless-steel bioreactor of original design and applied to the continuous alcoholic fermentation of a mixture of glucose (35 g dm-3) and xylose (15 g dm-3). Various dilution rates and initial cell loadings of the gel layer were tested. Simultaneous consumption of the two sugars was always observed. The best fermentation performance was obtained at low dilution rate (0.02 h-1) with an excess of C. Shehatae over S. cerevisiae in the initial cell loading of the gel (5.0 mg dry weight and 0.65 mg dry weight cm-3 gel respectively): 100% of glucose and 73% of xylose were consumed with an ethanol yield coefficient of 0.48 g g total sugars-1. In these conditions, however, the ethanol production rate per unit volume of gel remained low (0.37 g h-1 dm-3). Viable cell counts in gel samples after incubation highlighted significant heterogeneities in the spatial distribution of the two yeast species in both the vertical and the transverse directions. In particular, the overall cell number decreased from the bottom to the top of the agar sheet, which may explain the low ethanol productivity relative to the total gel volume.
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continuous alcoholic fermentation of glucose xylose mixtures by co immobilized saccharomyces cerevisiae and Candida Shehatae
Applied Microbiology and Biotechnology, 1998Co-Authors: Thierry Lebeau, Thierry Jouenne, Guy-alain JunterAbstract:Viable Saccharomyces cerevisiae and Candida Shehatae cells were co-immobilized in a composite agar layer/microporous membrane structure. This immobilized-cell structure was placed in a vertical position between the two halves of a double-chambered, stainless-steel bioreactor of original design and applied to the continuous alcoholic fermentation of a mixture of glucose (35 g dm−3) and xylose (15 g dm−3). Various dilution rates and initial cell loadings of the gel layer were tested. Simultaneous consumption of the two sugars was always observed. The best fermentation performance was obtained at low dilution rate (0.02 h−1) with an excess of C. Shehatae over S. cerevisiae in the initial cell loading of the gel (5.0 mg dry weight and 0.65 mg dry weight cm−3 gel respectively): 100% of glucose and 73% of xylose were consumed with an ethanol yield coefficient of 0.48 g g total sugars−1. In these conditions, however, the ethanol production rate per unit volume of gel remained low (0.37 g h−1 dm−3). Viable cell counts in gel samples after incubation highlighted significant heterogeneities in the spatial distribution of the two yeast species in both the vertical and the transverse directions. In particular, the overall cell number decreased from the bottom to the top of the agar sheet, which may explain the low ethanol productivity relative to the total gel volume.
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influence of the oxygenation level on d xylose fermentation by free and agar entrapped cultures of Candida Shehatae
Applied Microbiology and Biotechnology, 1995Co-Authors: C Hinfray, Thierry Jouenne, L Mignot, Guy-alain JunterAbstract:This paper investigates the effects of the oxygenation level on the performance of d-xylose alcoholic fermentation by free- and immobilized-cell batch cultures of Candida Shehatae (ATCC 22984). Yeast cells were immobilized in composite agar layer/microporous membrane structures. Fermentations were performed under varying oxygenation levels corresponding to different O2 flow rates (OFRs). Low OFRs enhanced the fermentation performance of free and immobilized yeasts. The best ethanol yield coefficient, obtained at an OFR of 5 mmol O2 h−1 dm−3 for both culture modes, was slightly higher (0.425 g g−1) for immobilized cultures than for their free counterparts (0.39 g g−1). More sustained aeration inhibited ethanol production by free and immobilized organisms. However, this inhibition was more pronounced for agar-entrapped cultures. Xylitol production of free cultures normally decreased as the OFR increased. At high OFR, however, immobilized organisms surprisingly produced more xylitol than at lower OFR or in anaerobiosis. This effect is discussed by referring to the mass transfer limitations that occur inside the immobilized-cell structures. Gel-entrapped cultures displayed higher specific and volumetric production rates of ethanol and xylitol than free-cell cultures.
F Camacho - One of the best experts on this subject based on the ideXlab platform.
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the fermentation of mixtures of d glucose and d xylose by Candida Shehatae pichia stipitis or pachysolen tannophilus to produce ethanol
Journal of Chemical Technology & Biotechnology, 2002Co-Authors: Sebastián Sánchez, Vicente Bravo, Eulogio Castro, Alberto J Moya, F CamachoAbstract:The fermentation of mixtures of D-glucose and D-xylose by three non-traditional yeasts: Candida Shehatae (ATCC 34887), Pachysolen tannophilus (ATCC 32691) and Pichia stipitis (ATCC 58376) have been studied to determine the optimal strain and initial culture conditions for the efficient production of ethanol. The comparison was made on the basis of maximum specific growth rate (µm), biomass productivity, the specific rates of total substrate consumption (qs) and ethanol production (qE) and the overall yields of ethanol and xylitol. All the experiments were performed in stirred-tank batch reactors at a temperature of 30 °C. The initial pH of the culture medium was 4.5. The highest values of µm (above 0.5 h−1) were obtained with P stipitis in cultures containing high concentrations of D-xylose. All three yeasts consumed the two monosaccharides in sequence, beginning with D-glucose. The values of qs diminished during the course of each experiment with all of the yeasts. The highest values of the specific rates of total substrate consumption and ethanol production were obtained with C Shehatae (for t = 10 h, qs and qE were above 5 g g−1 h−1 and 2 g g−1 h−1, respectively), although the highest overall ethanol yields were fairly similar with all three yeasts, at around 0.4 g g−1. © 2002 Society of Chemical Industry
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comparative study of the fermentation of d glucose d xylose mixtures with pachysolen tannophilus and Candida Shehatae
Bioprocess Engineering, 1999Co-Authors: Sebastián Sánchez, Vicente Bravo, Eulogio Castro, Alberto J Moya, F CamachoAbstract:We have performed a comparative analysis of the fermentation of the solutions of the mixtures of D-glucose and D-xylose with the yeasts Pachysolen tannophilus (ATCC 32691) and Candida Shehatae (ATCC 34887), with the aim of producing bioethanol. All the experiments were performed in a batch bioreactor, with a constant aeration level, temperature of 30 °C, and a culture medium with an initial pH of 4.5. For both yeasts, the comparison was established on the basis of the following parameters: maximum specific growth rate, biomass productivity, specific rate of substrate consumption (qs) and of ethanol production (qE), and overall ethanol and xylitol yields. For the calculation of the specific rates of substrate consumption and ethanol production, differential and integral methods were applied to the kinetic data. From the experimental results, it is deduced that both Candida and Pachysolen sequentially consume the two substrates, first D-glucose and then D-xylose. In both yeasts, the specific substrate-consumption rate diminished over each culture. The values qs and qE proved higher in Candida, although the higher ethanol yield was of the same order for both yeasts, close to 0.4 kg kg−1.
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the influence of ph and aeration rate on the fermentation of d xylose by Candida Shehatae
Enzyme and Microbial Technology, 1997Co-Authors: Sebastián Sánchez, Vicente Bravo, Eulogio Castro, Alberto J Moya, F CamachoAbstract:The effects of the initial pH and air supply on the production of ethanol from d-xylose using the yeast Candida Shehatae in a batch reactor were investigated. The initial pH was altered within the range of 2.5–6.5 and the specific aeration rate from 0.0–0.3 v v−1 min−1. The results showed that the most favorable initial pH for ethanol production was 4.5 and aeration via the stirring vortex of the bioreactor was sufficient. Under these conditions, the maximum specific growth rate (μm) was 0.329 h−1; biomass production rate (b), 0.024 kg m−3 h−1; overall biomass yield (YxsG), 0.036 kg kg−1; the specific uptake rate of d-xylose (qs), 2.0 kg kg−1 h−1; and the specific ethanol production rate (qE), 0.72 kg kg−1 h−1 (both at 20 h culture time). The average xylitol yield (Yxys) was 0.078 kg kg−1 and the overall ethanol yield (YEsG), 0.41 kg kg−1. Both qs and qE diminished once the exponential growth phase was over.
Atcharaporn Jongmeesuk - One of the best experts on this subject based on the ideXlab platform.
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Bioethanol Fermentation From Acid/Base-Treated Water Hyacinth Biomass Using Fermentation Yeasts Saccharomyces Cerevisiae YRK 017 and Candida Shehatae ATCC 22984
International Journal of Renewable Energy Research, 2019Co-Authors: Cherdsak Maneeruttanarungroj, Duangjai Ochaikul, Atcharaporn JongmeesukAbstract:Water hyacinth is considered as one of most abundant lignocellulosic feedstock in Thailand. It has been selected as a substrate for producing ethanol at an economically feasible manner. This study focuses on the bioethanol production from enzyme-treated hydrolysate of acid/base pretreatment water hyacinth. Two different pretreatment methods of water hyacinth were used including either 2% v/v sulfuric acid or 2% w/v sodium hydroxide at 121°C for 15 min. After acid/base pretreatments, the biomass residues in order to release glucose molecules were treated with a commercial cellulase enzyme complex (ACCELLERASE ® 1500) at a concentration of 0.30 mL enzyme/g biomass residue. Two yeast species consisting of Saccharomyces cerevisiae YRK 017 and Candida Shehatae ATCC 22984 were separately used as inocula in fermentation process of the hydrolysate from enzymatic treatments. The results showed that ethanol yield obtained from acid pretreatment was slightly higher than the yield from base pretreatment. In acid pretreatment, S. cerevisiae YRK 017 could produce bioethanol in a yield of 3.82 + 0.10 g/L, whereas C. Shehatae ATCC 22984 could produce yielding 2.85 + 0.04 g/L.
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bioethanol fermentation from acid base treated water hyacinth biomass using fermentation yeasts saccharomyces cerevisiae yrk 017 and Candida Shehatae atcc 22984
International Journal of Renewable Energy Research, 2019Co-Authors: Cherdsak Maneeruttanarungroj, Duangjai Ochaikul, Atcharaporn JongmeesukAbstract:Water hyacinth is considered as one of most abundant lignocellulosic feedstock in Thailand. It has been selected as a substrate for producing ethanol at an economically feasible manner. This study focuses on the bioethanol production from enzyme-treated hydrolysate of acid/base pretreatment water hyacinth. Two different pretreatment methods of water hyacinth were used including either 2% v/v sulfuric acid or 2% w/v sodium hydroxide at 121°C for 15 min. After acid/base pretreatments, the biomass residues in order to release glucose molecules were treated with a commercial cellulase enzyme complex (ACCELLERASE ® 1500) at a concentration of 0.30 mL enzyme/g biomass residue. Two yeast species consisting of Saccharomyces cerevisiae YRK 017 and Candida Shehatae ATCC 22984 were separately used as inocula in fermentation process of the hydrolysate from enzymatic treatments. The results showed that ethanol yield obtained from acid pretreatment was slightly higher than the yield from base pretreatment. In acid pretreatment, S. cerevisiae YRK 017 could produce bioethanol in a yield of 3.82 + 0.10 g/L, whereas C. Shehatae ATCC 22984 could produce yielding 2.85 + 0.04 g/L.
Thierry Lebeau - One of the best experts on this subject based on the ideXlab platform.
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Long-term incomplete xylose fermentation, after glucose exhaustion, with Candida Shehatae co-immobilized with Saccharomyces cerevisiae.
Microbiological research, 2006Co-Authors: Thierry Lebeau, Thierry Jouenne, Guy-alain JunterAbstract:Saccharomyces cerevisiae and Candida Shehatae were co-immobilized in an agar sheet which was introduced in an original two-chambered bioreactor asymmetrically fed in a batch mode with a mixture of glucose and xylose in a ratio of 35:15. The two sugars were consumed simultaneously. All glucose was fermented but only 20% of xylose. After incubation, yeast cells recovered from different areas of the agar sheet (close to, called Hi, and distant from, called Ho, the substrate chamber) were cultured as suspended cells in fresh culture medium provided with xylose or the sugar mixture. Xylose utilization by gel released Hi yeasts was significantly delayed compared to the Ho culture. Ethanol consumption by Hi yeasts in the two-substrate medium occurred after glucose exhaustion despite the presence of xylose. The waste medium resulting from incubation of the immobilized-cell structure inhibited xylose utilization by C. Shehatae. Our results suggested that batch fermentation most probably favoured this incomplete xylose fermentation.
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Continuous alcoholic fermentation of glucose/xylose mixtures by co-immobilized Saccharomyces cerevisiae and Candida Shehatae
Applied microbiology and biotechnology, 1998Co-Authors: Thierry Lebeau, Thierry Jouenne, Guy-alain JunterAbstract:Viable Saccharomyces cerevisiae and Candida Shehatae cells were co-immobilized in a composite agar layer/microporous membrane structure. This immobilized-cell structure was placed in a vertical position between the two halves of a double-chambered, stainless-steel bioreactor of original design and applied to the continuous alcoholic fermentation of a mixture of glucose (35 g dm-3) and xylose (15 g dm-3). Various dilution rates and initial cell loadings of the gel layer were tested. Simultaneous consumption of the two sugars was always observed. The best fermentation performance was obtained at low dilution rate (0.02 h-1) with an excess of C. Shehatae over S. cerevisiae in the initial cell loading of the gel (5.0 mg dry weight and 0.65 mg dry weight cm-3 gel respectively): 100% of glucose and 73% of xylose were consumed with an ethanol yield coefficient of 0.48 g g total sugars-1. In these conditions, however, the ethanol production rate per unit volume of gel remained low (0.37 g h-1 dm-3). Viable cell counts in gel samples after incubation highlighted significant heterogeneities in the spatial distribution of the two yeast species in both the vertical and the transverse directions. In particular, the overall cell number decreased from the bottom to the top of the agar sheet, which may explain the low ethanol productivity relative to the total gel volume.
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continuous alcoholic fermentation of glucose xylose mixtures by co immobilized saccharomyces cerevisiae and Candida Shehatae
Applied Microbiology and Biotechnology, 1998Co-Authors: Thierry Lebeau, Thierry Jouenne, Guy-alain JunterAbstract:Viable Saccharomyces cerevisiae and Candida Shehatae cells were co-immobilized in a composite agar layer/microporous membrane structure. This immobilized-cell structure was placed in a vertical position between the two halves of a double-chambered, stainless-steel bioreactor of original design and applied to the continuous alcoholic fermentation of a mixture of glucose (35 g dm−3) and xylose (15 g dm−3). Various dilution rates and initial cell loadings of the gel layer were tested. Simultaneous consumption of the two sugars was always observed. The best fermentation performance was obtained at low dilution rate (0.02 h−1) with an excess of C. Shehatae over S. cerevisiae in the initial cell loading of the gel (5.0 mg dry weight and 0.65 mg dry weight cm−3 gel respectively): 100% of glucose and 73% of xylose were consumed with an ethanol yield coefficient of 0.48 g g total sugars−1. In these conditions, however, the ethanol production rate per unit volume of gel remained low (0.37 g h−1 dm−3). Viable cell counts in gel samples after incubation highlighted significant heterogeneities in the spatial distribution of the two yeast species in both the vertical and the transverse directions. In particular, the overall cell number decreased from the bottom to the top of the agar sheet, which may explain the low ethanol productivity relative to the total gel volume.
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simultaneous fermentation of glucose and xylose by pure and mixed cultures of saccharomyces cerevisiae and Candida Shehatae immobilized in a two chambered bioreactor
Enzyme and Microbial Technology, 1997Co-Authors: Thierry Lebeau, Thierry Jouenne, G A JunterAbstract:Varying amounts of viable Saccharomyces cerevisiae and Candida Shehatae cells were coimmobilized in a composite structure consisting of a flat agar layer encompassed between two microporous membrane filters. This immobilized cell system was placed between the two halves of a two-chambered bioreactor and tested for ethanol production from a glucose-xylose mixture. One chamber of the bioreactor was filled with the sugar mixture whereas the second compartment received an equal volume of a substrate-free mineral medium. Batch incubation of the immobilized cell structure was performed at 30°C under two different oxygenation conditions: limited aerobiosis in both bioreactor chambers (symmetrical aeration) and asymmetrical oxygen supply obtained by continuous gas bubbling in the two bioreactor compartments, i.e., anaerobiosis in the substrate chamber (N2 bubbling) and microaerobiosis in the buffer chamber (bubbling of a O2N2 mixture at low O2 content). Pure cultures and cocultures of S. cerevisiae and C. Shehatae were able to simultaneously consume glucose and xylose, producing ethanol and xylitol. The fermentation efficiency of immobilized cell mixtures was no higher than that of pure cultures, however. Asymmetrical oxygenation conditions affected the fermentation performance of immobilized cultures. Coimmobilized S. cerevisiae and C. Shehatae both displayed growth inside the composite structure. Biofilm-like gel areas of high cell density appeared behind the microporous membrane filters during incubation of immobilized organisms. The cell number and repartition of the two yeasts in the gel layer depended on their relative proportions in the initial cell loading and the oxygenation conditions of the structure.
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fermentation alcoolique de melanges glucose xylose par les levures Candida Shehatae et saccharomyces cerevisiae co immobilisees dans un nouveau type de bioreacteur a membrane
1997Co-Authors: Thierry LebeauAbstract:Ce travail etudie la fermentation alcoolique d'un melange de glucose (35 g/l) et de xylose (15 g/l) par Candida Shehatae et Saccharomyces cerevisiae co-immobilisees dans une structure membranaire composite constituee d'une couche plane d'agar enserree entre deux membranes microporeuses. L'utilisation d'un bioreacteur a double chambre a permis une alimentation dissymetrique en substrats et en dioxygene de la structure immobilisatrice et de repondre ainsi aux exigences de culture de chacune des deux especes. Lors de fermentations discontinues, nous avons montre que les levures consommaient totalement le glucose mais seulement 25% a 40% du xylose. Afin de comprendre les raisons de la faible conversion du xylose par les levures immobilisees, nous avons evalue la resistance opposee par la structure biocatalytique a la diffusion des divers solutes (glucose, xylose, ethanol et xylitol). Cette resistance double au cours de l'incubation : une augmentation de cet ordre ne peut expliquer a elle seule le blocage du systeme. Une etude des capacites fermentaires des cellules extraites de la structure immobilisatrice a montre que les levures localisees pres de la source de substrats carbones subissaient un fort stress, probablement du a l'accumulation de co-metabolites toxiques dans le milieu de culture. Nous avons enfin effectue des fermentations en continu dans un prototype de bioreacteur a double chambre possedant une surface d'echange elargie. Un taux de conversion du xylose de 73% (et de 100% pour le glucose) a pu etre atteint pour un taux de dilution D de 0,04 h(-1), bien que la charge microbienne initiale du gel d'agar fut relativement faible (2,5 g/l de Candida Shehatae + 2,5 g/l de Saccharomyces cerevisiae).
