Synergistic temperature and ethanol effect on Saccharomyces cerevisiae dynamic behaviour in ethanol bio-fuel production

Aldiguier, A. S.; Alfenore, Sandrine; Cameleyre, Xavier; Goma, G.; Uribelarrea, Jean‐Louis; Guillouet, Stéphane; Molina-Jouve, Carole

doi:10.1007/s00449-004-0352-6

Cited by 86 publications

(63 citation statements)

References 23 publications

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“…Increasing glycerol production was also reported after submitting yeast cells to heat shock (12,20). A growth-coupled glycerol formation was also reported to be enhanced during aerobic ethanolic fermentation with increasing temperatures within the range of 27 to 33°C, whereas a decoupling phenomenon occurred above 33°C, pointing out a possible role of glycerol in yeast thermal protection (1).…”

Section: Discussionmentioning

confidence: 78%

Minimization of Glycerol Production during the High-Performance Fed-Batch Ethanolic Fermentation Process in Saccharomyces cerevisiae , Using a Metabolic Model as a Prediction Tool

Bideaux

Alfenore

Cameleyre

et al. 2006

Appl Environ Microbiol

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On the basis of knowledge of the biological role of glycerol in the redox balance of Saccharomyces cerevisiae, a fermentation strategy was defined to reduce the surplus formation of NADH, responsible for glycerol synthesis. A metabolic model was used to predict the operating conditions that would reduce glycerol production during ethanol fermentation. Experimental validation of the simulation results was done by monitoring the inlet substrate feeding during fed-batch S. cerevisiae cultivation in order to maintain the respiratory quotient (RQ) (defined as the CO 2 production to O 2 consumption ratio) value between 4 and 5. Compared to previous fermentations without glucose monitoring, the final glycerol concentration was successfully decreased. Although RQ-controlled fermentation led to a lower maximum specific ethanol production rate, it was possible to reach a high level of ethanol production: 85 g · liter ؊1 with 1.7 g · liter ؊1 glycerol in 30 h. We showed here that by using a metabolic model as a tool in prediction, it was possible to reduce glycerol production in a very high-performance ethanolic fermentation process.It is well-known that glycerol is a major by-product during alcoholic fermentation in the yeast Saccharomyces cerevisiae. The role of glycerol in the cellular redox balance (5) and in osmoregulation (4, 16) have been reported in the literature. Participating in the cell redox balance, glycerol is produced by Saccharomyces cerevisiae to reoxidize surplus NADH, formed in the synthesis of biomass and secondary fermentation products, to NAD ϩ (5). Two different strategies for modulating the production of glycerol have been reported in the literature. One strategy is to change the operating conditions of the fermentation process (i.e., aeration levels, stress conditions [salts, acids, osmotic stress, heat shock . . .]) (3,4,8,11,12,19,31,40,42); another is to use genetically modified strains. Engineered strains were constructed by overexpressing and repressing components of the glycerol synthesis pathway (14,18,19,21,25).Complementing biochemical and metabolic engineering experimental approaches, mathematical models may also be useful for interpretation and prediction of biochemical processes. Process models consist in coupling mass balance equations at the reactor scale and at the cellular scale (29). Cells can be modeled at different levels: unstructured models on the population level (15, 27) or structured models on the cellular level. The latter can be a compartmental model (41) or a metabolic regulator model (28). Constraints on carbon, energy, and redox potential linked to the metabolic network can be taken into account by a metabolic model that contains a complete set of metabolic pathways involved in biomass synthesis, energy production, substrate degradation, and cometabolite production (30,35).Metabolic flux analysis is generally used to quantify intracellular fluxes in the central metabolism of microorganisms (7,9,11,22,24,43), but it has had a limited impact due to the lack of regulatory...

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Section: Discussionmentioning

confidence: 78%

Minimization of Glycerol Production during the High-Performance Fed-Batch Ethanolic Fermentation Process in Saccharomyces cerevisiae , Using a Metabolic Model as a Prediction Tool

Bideaux

Alfenore

Cameleyre

et al. 2006

Appl Environ Microbiol

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“…The inhibitors, in combination with the synergism between the ethanol concentration and fermentation temperature that was needed to facilitate the enzymatic hydrolysis during SSCF [43], likely adversely affected the viability. In our fed-batch SSCF of whole slurry, the decrease in viability caused glucose to accumulate in the bioreactor after 72 h of co-fermentation (Fig.…”

Section: Fed-batch Sscf Of Whole Slurrymentioning

confidence: 99%

Sequential Targeting of Xylose and Glucose Conversion in Fed-Batch Simultaneous Saccharification and Co-fermentation of Steam-Pretreated Wheat Straw for Improved Xylose Conversion to Ethanol

et al. 2017

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Efficient conversion of both glucose and xylose in lignocellulosic biomass is necessary to make secondgeneration bioethanol from agricultural residues competitive with first-generation bioethanol and gasoline. Simultaneous saccharification and co-fermentation (SSCF) is a promising strategy for obtaining high ethanol yields. However, with this method, the xylose-fermenting capacity and viability of yeast tend to decline over time and restrict the xylose utilization. In this study, we examined the ethanol production from steampretreated wheat straw using an established SSCF strategy with substrate and enzyme feeding that was previously applied to steam-pretreated corn cobs. Based on our findings, we propose an alternative SSCF strategy to sustain the xylose-fermenting capacity and improve the ethanol yield. The xylose-rich hydrolyzate liquor was separated from the glucose-rich solids, and phases were co-fermented sequentially. By prefermentation of the hydrolyzate liquor followed fedbatch SSCF, xylose, and glucose conversion could be targeted in succession. Because the xylose-fermenting capacity declines over time, while glucose is still converted, it was advantageous to target xylose conversion upfront. With our strategy, an overall ethanol yield of 84% of the theoretical maximum based on both xylose and glucose was reached for a slurry with higher inhibitor concentrations, versus 92% for a slurry with lower inhibitor concentrations. Xylose utilization exceeded 90% after SSCF for both slurries. Sequential targeting of xylose and glucose conversion sustained xylose fermentation and improved xylose utilization and ethanol yield compared with fed-batch SSCF of whole slurry.

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“…However, as the glycerol production yield related to the biomass was found to be much higher in R2, it suggested a potential stress response of the yeast. Such a high yield was indeed measured when the yeast was submitted to variation of medium osmotic pressure [31,32] or temperature [33][34][35].…”

Section: Xt1_exp Xv1_expmentioning

confidence: 99%

Very high ethanol productivity in an innovative continuous two-stage bioreactor with cell recycle

Chaabane

Aldiguier

Alfenore³

et al. 2006

Bioprocess Biosyst Eng

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The performance of an innovative two-stage continuous bioreactor with cell recycle-potentially capable of giving very high ethanol productivity-was investigated. The first stage was dedicated to cell growth, whereas the second stage was dedicated to ethanol production. A high cell density was obtained by an ultrafiltration module coupled to the outlet of the second reactor. A recycle loop from the second stage to the first one was tested to improve cell viability and activity. Cultivations of Saccharomyces cerevisiae in mineral medium on glucose were performed at 30 degrees Celsius and pH 4. At steady state, total biomass concentrations of 59 and 157 gDCW l(-1) and ethanol concentrations of 31 and 65 g l(-1) were obtained in the first and second stage, respectively. The residual glucose concentration was 73 g l(-1) in the first stage and close to zero in the second stage. The present study shows that a very high ethanol productivity (up to 41 g l(-1) h(-1)) can indeed be obtained with complete conversion of the glucose and with a high ethanol titre (8.3 degrees GL) in the two-stage system.

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Synergistic temperature and ethanol effect on Saccharomyces cerevisiae dynamic behaviour in ethanol bio-fuel production

Cited by 86 publications

References 23 publications

Minimization of Glycerol Production during the High-Performance Fed-Batch Ethanolic Fermentation Process in Saccharomyces cerevisiae , Using a Metabolic Model as a Prediction Tool

Minimization of Glycerol Production during the High-Performance Fed-Batch Ethanolic Fermentation Process in Saccharomyces cerevisiae , Using a Metabolic Model as a Prediction Tool

Sequential Targeting of Xylose and Glucose Conversion in Fed-Batch Simultaneous Saccharification and Co-fermentation of Steam-Pretreated Wheat Straw for Improved Xylose Conversion to Ethanol

Very high ethanol productivity in an innovative continuous two-stage bioreactor with cell recycle

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