Bioenergy II: Comparison of Laboratory and Industrial Saccharomyces cerevisiae Strains for their Stress Tolerance

Geng, Anli; Wang, Zhankun; Lai, Kok Soon; Tan, Mark Wei Yi

doi:10.2202/1542-6580.1943

Cited by 3 publications

(4 citation statements)

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“…In the bioreactor assay with S. cerevisiae, better fermentation performance was expected, since the pH was automatically controlled to 5.5. While in the correspondent Erlenmeyer assay, the pH dropped to values as low as 3.01 and, although S. cerevisiae ATCC 24860 presents a high pH tolerance, this yeast strain is known to be affected when the pH drops below 4 [47].…”

Section: Bioreactor Assaysmentioning

confidence: 99%

“…Although yeasts can detoxify microbial inhibitors, such as furfural and HMF, the detoxification mechanisms compete for key enzymes and cofactors needed to channel the carbon flow to respiration or ethanol production [46]. On the other hand, S. cerevisiae is commonly used as a wine deacidifying yeast and, according to Geng et al (2010), S. cerevisiae ATCC 24860 showed high resistance to inhibitors usually present in LCB hydrolysates (i.e., formic acid, acetic acid, furfural, and HMF) [47].…”

Section: Erlenmeyer Flask Mono-culture Assaysmentioning

confidence: 99%

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Ethanol Production from Hydrolyzed Kraft Pulp by Mono- and Co-Cultures of Yeasts: The Challenge of C6 and C5 Sugars Consumption

et al. 2020

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Second-generation bioethanol production's main bottleneck is the need for a costly and technically difficult pretreatment due to the recalcitrance of lignocellulosic biomass (LCB). Chemical pulping can be considered as a LCB pretreatment since it removes lignin and targets hemicelluloses to some extent. Chemical pulps could be used to produce ethanol. The present study aimed to investigate the batch ethanol production from unbleached Kraft pulp of Eucalyptus globulus by separate hydrolysis and fermentation (SHF). Enzymatic hydrolysis of the pulp resulted in a glucose yield of 96.1 ± 3.6% and a xylose yield of 94.0 ± 7.1%. In an Erlenmeyer flask, fermentation of the hydrolysate using Saccharomyces cerevisiae showed better results than Scheffersomyces stipitis. At both the Erlenmeyer flask and bioreactor scale, co-cultures of S. cerevisiae and S. stipitis did not show significant improvements in the fermentation performance. The best result was provided by S. cerevisiae alone in a bioreactor, which fermented the Kraft pulp hydrolysate with an ethanol yield of 0.433 g·g −1 and a volumetric ethanol productivity of 0.733 g·L −1 ·h −1 , and a maximum ethanol concentration of 19.24 g·L −1 was attained. Bioethanol production using the SHF of unbleached Kraft pulp of E. globulus provides a high yield and productivity.Energies 2020, 13, 744 2 of 15 sustainability, has a low and stable price, and practically does not demand extra land [6,7]. There are some facilities producing 2G bioethanol on a commercial scale. However, large-scale production still faces some technological barriers that must be overcome in order to achieve a cost-competitive production [8]. Due to the recalcitrance of LCB, a costly pretreatment step is required, which is the main technological bottleneck of 2G bioethanol production. The release of enzymatic and fermentation inhibitors during pretreatment is another limitation [9].Pulp and paper mills have the infrastructures and logistics to handle LCB, and chemical mills employ technology required for LCB fractionation and conversion [10]. Bioethanol has been produced from different feedstocks such as Kraft pulp, spent sulfite liquor, and pulp and paper sludge [11]. Chemical pulping processes can be considered as a LCB pretreatment since they promote delignification and target hemicelluloses to some degree [12]. Chemical pulping represents about 77% of the virgin pulps produced globally, and more than 95% of these chemical pulps are Kraft pulps [13]. These pulps are produced by Kraft pulping involving the reaction of white liquor, i.e., an alkaline aqueous solution of sodium hydroxide and sodium sulfide with a pH of 14, with lignin at high temperature (150-170 • C). This reaction promotes lignin breakdown and degradation with the release of phenolic fragments, removing almost 90% of the lignin from the wood. Kraft pulping also leads to hemicelluloses and some cellulose loss and decreases the degree of polymerization of cellulose [14]. The utilization of Kraft pulping as a pretreatment method for LCB has ...

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Section: Bioreactor Assaysmentioning

confidence: 99%

Section: Erlenmeyer Flask Mono-culture Assaysmentioning

confidence: 99%

Ethanol Production from Hydrolyzed Kraft Pulp by Mono- and Co-Cultures of Yeasts: The Challenge of C6 and C5 Sugars Consumption

et al. 2020

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“…Saccharomyces cerevisiae ATCC 24860 was used in the ethanol fermentation studies. This strain has been reported to possess a high stress tolerance against pH, inhibitors, xylose, temperature and ethanol (Geng et al, 2010). It was preserved at 4°C and maintained on yeast and mold (YM) agar medium which contained (g L −1 ): 10, yeast extract; 10, peptone; 20, glucose; 20, agar (pH 6).…”

Section: Ethanol Fermentationmentioning

confidence: 99%

Optimization of Enzymatic Hydrolysis of Corn Stover for Improved Ethanol Production

Zambare¹,

Christopher

2012

Energy Exploration & Exploitation

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Response surface methodology (RSM) was used to optimize the enzymatic hydrolysis of corn stover (CS), an abundant agricultural residue in the USA. A five-level, three-variable central composite design (CCD) was employed in a total of 20 experiments to model and evaluate the impact of pH (4.1-6.0), solids loadings (6.6-23.4%), and enzyme loadings (6.6−23.4 FPU g −1 DM) on glucose yield from thermo-mechanically extruded CS. The extruded CS was first hydrolyzed with the crude cellulase of Penicillium pinophilum ATCC 200401 and then fermented to ethanol with Saccharomyces cerevisiae ATCC 24860. Although all three variables had a significant impact, the enzyme loadings proved the most significant parameter for maximizing the glucose yield. A partial cubic equation could accurately model the response surface of enzymatic hydrolysis as the analysis of variance (ANOVA) showed a coefficient of determination (R 2 ) of 0.82. At the optimal conditions of pH of 4.5, solids loadings of 10% and enzyme loadings of 20 FPU g −1 DM, the enzymatic hydrolysis of pretreated CS produced a glucose yield of 57.6% of the glucose maximum yield which was an increase of 10.4% over the non-optimized controls at zero-level central points. The predicted results based on the RSM regression model were in good agreement with the actual experimental values. The model can present a rapid means for estimating lignocellulose conversion yields within the selected ranges.

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“…This strain has been reported to possess a high stress tolerance against pH, inhibitors, xylose, temperature, and ethanol. 32 It was preserved at 4 C and maintained on yeast and mold (YM) agar medium which contained (g/l): 10, yeast extract; 10, peptone; 20, glucose; 20, agar (pH 6). Inoculum was grown in Erlenmeyer flasks containing 100 ml of YM broth on an orbital shaker at 30 C and 150 rpm.…”

Section: G Ethanol Fermentationmentioning

confidence: 99%

Optimization of enzymatic hydrolysis of prairie cordgrass for improved ethanol production

Zambare

Barh

et al. 2012

Journal of Renewable and Sustainable Energy

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Prairie cordgrass (PCG), Spartina pectinata, is considered an energy crop with potential for bioethanol production in North America. The focus of this study was to optimize enzymatic hydrolysis of PCG at higher solids loadings using a thermostable cellulase of a mutant Penicillium pinophilum ATCC 200401. A three variable, fivelevel central composite design of response surface methodology (RSM) was employed in a total of 20 experiments to model and evaluate the impact of pH (4.1-6.0), solids loadings (6.6%-23.4%), and enzyme loadings (6.6-23.4 FPU/g dry matter, DM) on glucose yield from a thermo-mechanically extruded PCG. The extruded PCG was first hydrolyzed with the crude P. pinophilum cellulase and then fermented to ethanol with Saccharomyces cerevisiae ATCC 24860. Although all three variables had a significant impact, the enzyme loadings proved the most significant parameter for maximizing the glucose yield. A partial cubic equation could accurately model the response surface of enzymatic hydrolysis as the analysis of variance showed a coefficient of determination (R 2 ) of 0.89. At the optimal conditions of pH of 4.5, solids loadings of 10% and enzyme loadings of 20 FPU/g DM, the enzymatic hydrolysis of pretreated PCG produced a glucose yield of 76.1% from the maximum yield which represents an increase of 15% over the nonoptimized controls at the zero-level central points. The predicted results based on the RSM regression model were in good agreement with the actual experimental values. The model can present a rapid means for estimating lignocellulose conversion yields within the selected ranges. Furthermore, statistical optimization of solids and enzyme loadings of enzymatic hydrolysis of biomass may have important implications for reduced capital and operating costs of ethanol production. V C 2012 American Institute of Physics. [http://dx.

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Bioenergy II: Comparison of Laboratory and Industrial Saccharomyces cerevisiae Strains for their Stress Tolerance

Cited by 3 publications

References 0 publications

Ethanol Production from Hydrolyzed Kraft Pulp by Mono- and Co-Cultures of Yeasts: The Challenge of C6 and C5 Sugars Consumption

Ethanol Production from Hydrolyzed Kraft Pulp by Mono- and Co-Cultures of Yeasts: The Challenge of C6 and C5 Sugars Consumption

Optimization of Enzymatic Hydrolysis of Corn Stover for Improved Ethanol Production

Optimization of enzymatic hydrolysis of prairie cordgrass for improved ethanol production

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