Dynamic model of temperature impact on cell viability and major product formation during fed-batch and continuous ethanolic fermentation in Saccharomyces cerevisiae

Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077 Toulouse, France.
Bioresource Technology (Impact Factor: 4.49). 04/2012; 117:242-50. DOI: 10.1016/j.biortech.2012.04.013
Source: PubMed


The impact of the temperature on an industrial yeast strain was investigated in very high ethanol performance fermentation fed-batch process within the range of 30-47 °C. As previously observed with a lab strain, decoupling between growth and glycerol formation occurred at temperature of 36 °C and higher. A dynamic model was proposed to describe the impact of the temperature on the total and viable biomass, ethanol and glycerol production. The model validation was implemented with experimental data sets from independent cultures under different temperatures, temperature variation profiles and cultivation modes. The proposed model fitted accurately the dynamic evolutions for products and biomass concentrations over a wide range of temperature profiles. R2 values were above 0.96 for ethanol and glycerol in most experiments. The best results were obtained at 37 °C in fed-batch and chemostat cultures. This dynamic model could be further used for optimizing and monitoring the ethanol fermentation at larger scale.

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    • "Biofuel, a renewable and clean energy source, is considered as an effective substitute for petroleum-based products [1]. Among various types of biofuels, bio-ethanol is most popular and has a great potential to replace the motor fuels [2] [3] [4] [5]. In order to obtain the ethanol product with a high purity from the commercial fermentation process, efficient purification process is needed [6], which actually accounts for 60–80% in the overall cost of alcohol production in the current situation. "
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    • "In other words, the concentrations of ethanol and xylitol reached 55 g/L (yield of 0.70 g/g) and 31 g/L (yield of 0.78 g/g) at the 150th hour, respectively, which were significantly higher than those obtained in the batch single and co-culture systems (Fig. 6). Numerous studies have previously emphasized on the advantages of continuous production of ethanol and therefore strived to produce ethanol from different biomass by using different continuous fermentation systems, such as cell recycling or/and in situ ethanol removal (e.g., Zhang et al. 2005; Chen et al. 2012; Ntihuga et al. 2012), modeling or/ and optimizing different fermentation parameters (e.g., Amillastre et al. 2012; Khongsay et al. 2012; Sharma and Rangaiah 2012), and using different fermentor designs and fermentation techniques (e.g., Ding et al. 2011; Kundiyana et al. 2011; Moon et al. 2012). Our results also proved the great advantage of continuous co-production of ethanol and xylitol from rice straw feedstock over batch single production. "
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    • "In this context, ethanol has a prominent role, its worldwide production indicators having risen from control (Ngwenya et al., 2012). Indeed the effects of inadequate temperature conditions include reduction of fermentation yield, changes in cell viability and decrease of yeast tolerance to ethanol (Amillastre et al., 2012). Besides, fermentation under suboptimal temperatures can favor wild microorganism which will compete with S. cerevisiae for substrate. "
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