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Fikret Kargi - One of the best experts on this subject based on the ideXlab platform.

  • Ethanol Fermentation of cheese whey powder solution by repeated fed batch operation
    Enzyme and Microbial Technology, 2007
    Co-Authors: Serpil Ozmihci, Fikret Kargi
    Abstract:

    Abstract Ethanol Fermentation of cheese whey powder (CWP) solution was realized in a fed-batch operated fermenter using the pure culture of Kluyveromyces marxianus (DSMZ 7239) at different feed CWP concentrations varying between 51 and 408 g l −1 . Total sugar content of the feed varied between 25 and 200 g l −1 with a constant flow rate of 0.084 l h −1 . Sugar utilization, Ethanol formation and biomass growth were investigated as function of the feed sugar concentration in a five-cycle repeated fed-batch operation where the system reached the quasi steady-state. Variations of the growth and the product yield coefficients with the feed sugar concentration were quantified. The growth yield coefficient ( Y X / S ) decreased with increasing feed sugar concentrations. The product yield coefficient ( Y P / S ) was almost constant (0.54 ± 0.02 g EtOH g −1 S ) for sugar concentrations between 25 and 150 g l −1 , but decreased at the feed sugar concentration of 200 g l −1 due to high osmotic pressure at high sugar concentrations. The highest Ethanol concentration (63 g l −1 ) and the productivity (5.3 g EtOH h −1 ) were obtained with a 125 g l −1 feed sugar concentration and sugar loading rate of 10.5 g  S  h −1 .

  • comparison of yeast strains for batch Ethanol Fermentation of cheese whey powder cwp solution
    Letters in Applied Microbiology, 2007
    Co-Authors: Serpil Ozmihci, Fikret Kargi
    Abstract:

    Aims: To test the suitability of cheese whey powder (CWP) solution for Ethanol Fermentation and to compare performances of different Kluyveromyces marxianus strains for Ethanol Fermentation from CWP solution. Methods and Results: Batch Ethanol Fermentation of cheese whey (CW), CWP and lactose solutions with the same initial sugar contents were compared by using two different K. marxianus strains and the CWP solution was found to be the most suitable substrate. CWP solution was fermented to Ethanol using three different yeast strains and DSMZ-7239 was found to be the most suitable one yielding the highest rate and extent (3AE3%, v ⁄ v) of Ethanol formation. Conclusions: CWP solution and K. marxianus strain of DSMZ-7239 were found to be more suitable for Ethanol Fermentation with the highest Ethanol yield when compared with the other substrates and the yeast strains tested. Significance and Impact of the Study: CWP can be used as a concentrated form of CW for Ethanol Fermentations with considerable advantages.

  • Continuous Ethanol Fermentation of cheese whey powder solution: effects of hydraulic residence time
    Bioprocess and Biosystems Engineering, 2007
    Co-Authors: Serpil Ozmihci, Fikret Kargi
    Abstract:

    Continuous Ethanol Fermentation of cheese whey powder solution was realized using pure culture of Kluyveromyces marxianus (DSMZ 7239) at hydraulic residence times (HRT) between 12.5 and 60 h. Sugar utilization, Ethanol and biomass formation were investigated as functions of HRT. Effluent sugar concentration decreased, but percent sugar utilization, Ethanol and biomass concentrations increased with HRT. Ethanol productivity was maximum (0.745 gE l^−1h^−1) at an HRT of 43.2 h where the biomass productivity was almost minimum (0.18 gX l^−1 h^−1). The Ethanol yield coefficient was almost constant at 0.4 gE g^−1S up to HRT of 43.2 h and the growth yield coefficient was minimum at HRT of 43.2 h. Kinetic models were developed and the constants were determined by using the experimental data.

Qiang Yong - One of the best experts on this subject based on the ideXlab platform.

  • Detoxification of Steam-Exploded Corn Stover Prehydrolyzate with Organobentonite Enhances Ethanol Fermentation by Pichia stipitis
    BioResources, 2016
    Co-Authors: Chenhuan Lai, Junjun Zhu, Qiang Yong
    Abstract:

    The inhibitors derived from degradation of lignocellulose have adverse impacts on Fermentation, which is considered to be a fundamental problem in bioEthanol production. Fermentation of steam-exploded corn stover prehydrolyzate by Pichia stipitis showed that phenolic compounds had much higher inhibitory effects than weak acids and furan at high Fermentation pH. Two types of organobentonite (cetyltrimethylammonium (CTMA)- and benzyltrimethylammonium (BTMA)-modified bentonite) were used to remove phenolic compounds in prehydrolyzate. The effectiveness of organobentonite treatment was evaluated by Ethanol Fermentation, which indicated that the organobentonite treatment improved the fermentability substantially, even though a noticeable difference was found in the phenol removal by the two organobentonites. Without organobentonite treatment, the sugar utilization ratio was only 68.1%, and the produced Ethanol was 15.36 g/L. After CTMA- and BTMA-bentonite treatment, the sugar utilization ratios were beyond 95%; meanwhile, the Ethanol production increased by 45.5% and 42.8%, respectively. This indicated that organobentonite treatment was a potential detoxification method.

  • cause analysis of the effects of acid catalyzed steam exploded corn stover prehydrolyzate on Ethanol Fermentation by pichia stipitis cbs 5776
    Bioprocess and Biosystems Engineering, 2014
    Co-Authors: Junjun Zhu, Jinlong Yang, Yuanyuan Zhu, Lingling Zhang, Qiang Yong
    Abstract:

    The prehydrolyzate obtained from acid-catalyzed steam-exploded corn stover (ASC) mainly contains xylose and a number of inhibitory compounds that inhibit Ethanol Fermentation by Pichia stipitis. In this study, the effects of the ASC prehydrolyzate, specifically those of the carbohydrate-degradation products, lignin-degradation products (which were extracted from ASC prehydrolyzate using ethyl acetate), and six major phenolic compounds (added to pure-sugar media individually or in combination), on Ethanol Fermentation were investigated. Results indicate that the effects of the carbohydrate-degradation products were negligible (10 h delayed) compared with those of pure-sugar Fermentation, whereas the effects of the lignin-degradation products were significant (52 h delayed). Meanwhile, the inhibitory effects of the major phenolic compounds were not caused by certain types of inhibitors, but were due to the synergistic effects of various inhibitors.

Serpil Ozmihci - One of the best experts on this subject based on the ideXlab platform.

  • Ethanol Fermentation of cheese whey powder solution by repeated fed batch operation
    Enzyme and Microbial Technology, 2007
    Co-Authors: Serpil Ozmihci, Fikret Kargi
    Abstract:

    Abstract Ethanol Fermentation of cheese whey powder (CWP) solution was realized in a fed-batch operated fermenter using the pure culture of Kluyveromyces marxianus (DSMZ 7239) at different feed CWP concentrations varying between 51 and 408 g l −1 . Total sugar content of the feed varied between 25 and 200 g l −1 with a constant flow rate of 0.084 l h −1 . Sugar utilization, Ethanol formation and biomass growth were investigated as function of the feed sugar concentration in a five-cycle repeated fed-batch operation where the system reached the quasi steady-state. Variations of the growth and the product yield coefficients with the feed sugar concentration were quantified. The growth yield coefficient ( Y X / S ) decreased with increasing feed sugar concentrations. The product yield coefficient ( Y P / S ) was almost constant (0.54 ± 0.02 g EtOH g −1 S ) for sugar concentrations between 25 and 150 g l −1 , but decreased at the feed sugar concentration of 200 g l −1 due to high osmotic pressure at high sugar concentrations. The highest Ethanol concentration (63 g l −1 ) and the productivity (5.3 g EtOH h −1 ) were obtained with a 125 g l −1 feed sugar concentration and sugar loading rate of 10.5 g  S  h −1 .

  • comparison of yeast strains for batch Ethanol Fermentation of cheese whey powder cwp solution
    Letters in Applied Microbiology, 2007
    Co-Authors: Serpil Ozmihci, Fikret Kargi
    Abstract:

    Aims: To test the suitability of cheese whey powder (CWP) solution for Ethanol Fermentation and to compare performances of different Kluyveromyces marxianus strains for Ethanol Fermentation from CWP solution. Methods and Results: Batch Ethanol Fermentation of cheese whey (CW), CWP and lactose solutions with the same initial sugar contents were compared by using two different K. marxianus strains and the CWP solution was found to be the most suitable substrate. CWP solution was fermented to Ethanol using three different yeast strains and DSMZ-7239 was found to be the most suitable one yielding the highest rate and extent (3AE3%, v ⁄ v) of Ethanol formation. Conclusions: CWP solution and K. marxianus strain of DSMZ-7239 were found to be more suitable for Ethanol Fermentation with the highest Ethanol yield when compared with the other substrates and the yeast strains tested. Significance and Impact of the Study: CWP can be used as a concentrated form of CW for Ethanol Fermentations with considerable advantages.

  • Continuous Ethanol Fermentation of cheese whey powder solution: effects of hydraulic residence time
    Bioprocess and Biosystems Engineering, 2007
    Co-Authors: Serpil Ozmihci, Fikret Kargi
    Abstract:

    Continuous Ethanol Fermentation of cheese whey powder solution was realized using pure culture of Kluyveromyces marxianus (DSMZ 7239) at hydraulic residence times (HRT) between 12.5 and 60 h. Sugar utilization, Ethanol and biomass formation were investigated as functions of HRT. Effluent sugar concentration decreased, but percent sugar utilization, Ethanol and biomass concentrations increased with HRT. Ethanol productivity was maximum (0.745 gE l^−1h^−1) at an HRT of 43.2 h where the biomass productivity was almost minimum (0.18 gX l^−1 h^−1). The Ethanol yield coefficient was almost constant at 0.4 gE g^−1S up to HRT of 43.2 h and the growth yield coefficient was minimum at HRT of 43.2 h. Kinetic models were developed and the constants were determined by using the experimental data.

Junjun Zhu - One of the best experts on this subject based on the ideXlab platform.

  • Detoxification of Steam-Exploded Corn Stover Prehydrolyzate with Organobentonite Enhances Ethanol Fermentation by Pichia stipitis
    BioResources, 2016
    Co-Authors: Chenhuan Lai, Junjun Zhu, Qiang Yong
    Abstract:

    The inhibitors derived from degradation of lignocellulose have adverse impacts on Fermentation, which is considered to be a fundamental problem in bioEthanol production. Fermentation of steam-exploded corn stover prehydrolyzate by Pichia stipitis showed that phenolic compounds had much higher inhibitory effects than weak acids and furan at high Fermentation pH. Two types of organobentonite (cetyltrimethylammonium (CTMA)- and benzyltrimethylammonium (BTMA)-modified bentonite) were used to remove phenolic compounds in prehydrolyzate. The effectiveness of organobentonite treatment was evaluated by Ethanol Fermentation, which indicated that the organobentonite treatment improved the fermentability substantially, even though a noticeable difference was found in the phenol removal by the two organobentonites. Without organobentonite treatment, the sugar utilization ratio was only 68.1%, and the produced Ethanol was 15.36 g/L. After CTMA- and BTMA-bentonite treatment, the sugar utilization ratios were beyond 95%; meanwhile, the Ethanol production increased by 45.5% and 42.8%, respectively. This indicated that organobentonite treatment was a potential detoxification method.

  • cause analysis of the effects of acid catalyzed steam exploded corn stover prehydrolyzate on Ethanol Fermentation by pichia stipitis cbs 5776
    Bioprocess and Biosystems Engineering, 2014
    Co-Authors: Junjun Zhu, Jinlong Yang, Yuanyuan Zhu, Lingling Zhang, Qiang Yong
    Abstract:

    The prehydrolyzate obtained from acid-catalyzed steam-exploded corn stover (ASC) mainly contains xylose and a number of inhibitory compounds that inhibit Ethanol Fermentation by Pichia stipitis. In this study, the effects of the ASC prehydrolyzate, specifically those of the carbohydrate-degradation products, lignin-degradation products (which were extracted from ASC prehydrolyzate using ethyl acetate), and six major phenolic compounds (added to pure-sugar media individually or in combination), on Ethanol Fermentation were investigated. Results indicate that the effects of the carbohydrate-degradation products were negligible (10 h delayed) compared with those of pure-sugar Fermentation, whereas the effects of the lignin-degradation products were significant (52 h delayed). Meanwhile, the inhibitory effects of the major phenolic compounds were not caused by certain types of inhibitors, but were due to the synergistic effects of various inhibitors.

Fengwu Bai - One of the best experts on this subject based on the ideXlab platform.

  • impact of osmotic stress and Ethanol inhibition in yeast cells on process oscillation associated with continuous very high gravity Ethanol Fermentation
    Biotechnology for Biofuels, 2013
    Co-Authors: Liang Wang, Xinqing Zhao, Chuang Xue, Fengwu Bai
    Abstract:

    Background VHG Fermentation is a promising process engineering strategy aiming at improving Ethanol titer, and thus saving energy consumption for Ethanol distillation and distillage treatment. However, sustained process oscillation was observed during continuous VHG Ethanol Fermentation, which significantly affected Ethanol Fermentation performance of the system.

  • Ethanol Fermentation with kluyveromyces marxianus from jerusalem artichoke grown in salina and irrigated with a mixture of seawater and freshwater
    Journal of Applied Microbiology, 2008
    Co-Authors: Wenjie Yuan, Xinqing Zhao, Fengwu Bai
    Abstract:

    Aims:  To study fuel Ethanol Fermentation with Kluyveromyces marxianus ATCC8554 from Jerusalem artichoke (Helianthus tuberosus) grown in salina and irrigated with a mixture of seawater and freshwater. Methods and Results:  The growth and Ethanol Fermentation of K. marxianus ATCC8554 were studied using inulin as substrate. The activity of inulinase, which attributes to the hydrolysis of inulin, the main carbohydrate in Jerusalem artichoke, was monitored. The optimum temperatures were 38°C for growth and inulinase production, and 35°C for Ethanol Fermentation. Aeration was not necessary for Ethanol Fermentation with the K. marxianus from inulin. Then, the fresh Jerusalem artichoke tubers grown in salina and irrigated with 25% and 50% seawater were further examined for Ethanol Fermentation with the K. marxianus, and a higher Ethanol yield was achieved for the Jerusalem artichoke tuber irrigated with 25% seawater. Furthermore, the dry meal of the Jerusalem artichoke tubers irrigated with 25% seawater was examined for Ethanol Fermentation at three solid concentrations of 200, 225 and 250 g l−1, and the highest Ethanol yield of 0·467, or 91·5% of the theoretical value of 0·511, was achieved for the slurry with a solid concentration of 200 g l−1. Conclusions:  Halophilic Jerusalem artichoke can be used for fuel Ethanol production. Significance and Impact of the Study:  Halophilic Jerusalem artichoke, not competing with grain crops for arable land, is a sustainable feedstock for fuel Ethanol production.

  • online monitoring and characterization of flocculating yeast cell flocs during continuous Ethanol Fermentation
    Biotechnology and Bioengineering, 2005
    Co-Authors: Xinqing Zhao, Fengwu Bai
    Abstract:

    Both intrinsic and observed kinetic investigations for those Ethanol Fermentations using self-flocculated yeast strains have been hindered by the lack of real online monitoring techniques and proper characterization methods for the flocs. An optical detecting technique, the focused beam reflectance measurement probe developed by Lasentec (Redmond, WA) was inserted into a fermentor to monitor the floc chord length distributions. Using a simulating system composed of the floc-buffer suspensions, the total floc chord length counts per second were directly correlated with the floc biomass concentrations so that the floc biomass concentrations can be in situ detected. Furthermore, a characterization method of the flocs was established by properly weighted treatments of the detected floc chord length distributions. When a real yeast floc Ethanol Fermentation system was detected during its intrinsic kinetic investigations in which the floc size needed to be controlled at a level of micrometer scale to eliminate inner mass transfer limitations, it was found and validated that CO(2) produced during Fermentation exerted significant disturbances. By applying 1/length-weighted treatment, these disturbances were effectively overcome.