[ Objective] The research aimed to explore the efficiency of ethanol production under the optimal conditions of separate hydrolysis and fermentation （SHF） and simultaneous saccharification and fermentation （SSF）. ...[ Objective] The research aimed to explore the efficiency of ethanol production under the optimal conditions of separate hydrolysis and fermentation （SHF） and simultaneous saccharification and fermentation （SSF）. [ Method ] Under the optimal conditions of hydrolysis and fermenta- tion, SHF and SSF process were designed respectively. SHF process was conducted under the optimal conditions of hydrolysis and fermentation separately, while SSF process was carried out at the optimum temperature of hydrolysis and fermentation. [ Result] In SHF process, the efficiency of ethanol production was similar during both supematant and mixture fermentation, and yeast was more active during the mixture fermentation. In SSF process, the efficiency of ethanol production was higher at 35 ℃, and the production of xylose was higher than that in hydrolysis process. [ Conclusion] Under the experimental conditions, the efficiency of ethanol production during simultaneous saccharification and fermentation was higher than that during separate hydrolysis and fermentation.展开更多
Lespedeza stalks were subjected to steam pretreatment at 210℃ for some steaming time before simultaneous saccharification and fermentation （SSF）. Cellulose-derived glucose was extensively utilized by yeast during S...Lespedeza stalks were subjected to steam pretreatment at 210℃ for some steaming time before simultaneous saccharification and fermentation （SSF）. Cellulose-derived glucose was extensively utilized by yeast during SSE The ethanol yields after steam pretreatment of the lespedeza stalks at 210℃ were 59.3%, 72.8% and 62.2% of the theoretically expected values when the steaming times were 2, 4 and 6 min, respectively. The highest yield from α-cellulose was 92.7% of the theoretical value. Steam explosion pretreatment of lespedeza stalks increased ethanol yields by a factor of 4.4, from 16.4% （untreated） to 72.8% （steam explosion pretreated）.展开更多
Chinese rice wine making is a typical simultaneous saccharification and fermentation （SSF） process. During the fermentation process, temperature is one of the key parameters which decide the quality of Chinese rice ...Chinese rice wine making is a typical simultaneous saccharification and fermentation （SSF） process. During the fermentation process, temperature is one of the key parameters which decide the quality of Chinese rice wine. To optimize the SSF process for Chinese rice wine brewing, the effects of temperature on the kinetic parameters of yeast growth and ethanol production at various temperatures were determined in batch cultures using a mathematical model. The kinetic parameters as a function of temperature were evaluated using the software Origin8.0. Combing these functions with the mathematical model, an appropriate form of the model equations for the SSF considering the effects of temperature were developed. The kinetic parameters were found to fit the experimental data satisfactorily with the developed temperature-dependent model. The temperature profile for maximizing the ethanol production for rice wine fermentation was determined by genetic algorithm. The optimum temperature profile began at a low temperature of 26℃ up to 30 h. The operating temperature increased rapidly to 31.9 ℃, and then decreased slowly to 18℃ at 65 h. Thereafter, the temperature was maintained at 18 ℃ until the end of fermentation. A maximum ethanol production of 89.3 g.L 1 was attained. Conceivably, our model would facilitate the improvement of Chinese rice wine production at the industrial scale.展开更多
The effects of process variables in Simultaneous Saccharification and Fermentation (SSF) of wheat bran flour were studied in bulk fermentation using a coculture of Aspergillus niger - Kluveromyces marxianus. The effec...The effects of process variables in Simultaneous Saccharification and Fermentation (SSF) of wheat bran flour were studied in bulk fermentation using a coculture of Aspergillus niger - Kluveromyces marxianus. The effect of substrate density, pH, temperature, and enzyme concentration on wheat bran was predicted by designing experiments in which a single parameter is varied keeping other variables at a constant level. The above parameters were optimized for a batch culture in a fermentor. Optimal values for substrate concentration, pH, temperature, and enzyme concentration during processing were 200 g/l, 5.5, 65°C, and 7.5 IU, respectively. In pre-treatment experiments, the concentration of enzymes and the pre-treatment temperature are highly correlated. The influence of pH, temperature, and substrate density on ethanol production was investigated. Temperature pH was determined as optimal, 32°C and 5.5, respectively. After 48 hours of fermentation at optimum pH, a solution of wheat bran containing a maximum of 6% starch produces a maximum of 22.9 g/l ethanol.展开更多
The Simultaneous Saccharification and Fermentation （SSF） of alkali-acid pretreated sugarcane trash to ethanol was optimized using commercial cellulase and Saccharomyces cerevisiae TISTR 5596 cells. Substrate concent...The Simultaneous Saccharification and Fermentation （SSF） of alkali-acid pretreated sugarcane trash to ethanol was optimized using commercial cellulase and Saccharomyces cerevisiae TISTR 5596 cells. Substrate concentration （12.5% w/v, 15% w/v, 17.5% w/v and 20% w/v）, enzyme loading （25 FPU/g Dry Substrate （DS）, 50 FPU/g DS and 75 FPU/g DS）, and temperature （30 ~C, 35 ~C and 40 ~C） were evaluated. The SSF optimal conditions for alkali-acid pretreated sugarcane trash were 20% w/v of substrate concentration, enzyme loading 50 FPU/g DS, temperature 35 ~C, initial pH 5.0 and yeast inoculum 107 cells/mL. Under the above optimal conditions, ethanol concentration was possible to reach in the range between 50.14 g/L and 55.08 g/L at 96 hrs and 144 hrs, respectively. This study could establish the effective utilization of sugarcane trash for bioethanol production using optimized fermentation parameters.展开更多
Studies on simultaneous saccharification and fermentation(SSF)of wheat bran flour,a grain milling residue as the substrate using coculture method were carried out with strains of starch digesting Aspergillus niger and...Studies on simultaneous saccharification and fermentation(SSF)of wheat bran flour,a grain milling residue as the substrate using coculture method were carried out with strains of starch digesting Aspergillus niger and nonstarch digesting and sugar fermenting Kluyveromyces marxianus in batch fermentation.Experi-ments based on central composite design(CCD)were conducted to maximize the glucose yield and to study the effects of substrate concentration,pH,temperature,and enzyme concentration on percentage conversion of wheat bran flour starch to glucose by treatment with fungalα-amylase and the above parameters were optimized using response surface methodology(RSM).The optimum values of substrate concentration,pH,temperature,and enzyme concentration were found to be 200g/L,5.5,65℃ and 7.5IU,respectively,in the starch saccharification step.The effects of pH,temperature and substrate concentration on ethanol concentration,biomass and reducing sugar concentration were also investigated.The optimum temperature and pH were found to be 30℃ and 5.5,respectively.The wheat bran flour solution equivalent to 6%(w/V)initial starch concentration gave the highest ethanol concentrationof 23.1g/Lafter 48hoffermentation at optimum conditions of pH and temperature.The growth kinetics was modeled using Monod model and Logistic model and product formation kinetics using Leudeking-Piret model.Simultaneous saccharificiation and fermenta-tion of liquefied wheat bran starch to bioethanol was studied using coculture of amylolytic fungus A.niger and nonamylolytic sugar fermenting K.marxianus.展开更多
Due to its merits of drought tolerance and high yield,sweet potatoes are widely considered as a potential alterative feedstock for bioethanol production.Very high gravity(VHG)technology is an effective strategy for im...Due to its merits of drought tolerance and high yield,sweet potatoes are widely considered as a potential alterative feedstock for bioethanol production.Very high gravity(VHG)technology is an effective strategy for improving the efficiency of ethanol fermentation from starch materials.However,this technology has rarely been applied to sweet potatoes because of the high viscosity of their liquid mash.To overcome this problem,cellulase was added to reduce the high viscosity,and the optimal dosage and treatment time were 8 U/g(sweet potato powder)and 1 h,respectively.After pretreatment by cellulase,the viscosity of the VHG sweet potato mash(containing 284.2 g/L of carbohydrates)was reduced by 81%.After liquefaction and simultaneous saccharification and fer-mentation(SSF),thefinal ethanol concentration reached 15.5%(v/v),and the total sugar conversion and ethanol yields were 96.5%and 87.8%,respectively.展开更多
Although simultaneous saccharification and fermentation(SSF)has been investigated extensively,the optimum condition for SSF of wheat straw has not yet been determined.Dilute sulfuric acid impregnated and steam explosi...Although simultaneous saccharification and fermentation(SSF)has been investigated extensively,the optimum condition for SSF of wheat straw has not yet been determined.Dilute sulfuric acid impregnated and steam explosion pretreated wheat straw was used as a substrate for the production of ethanol by SSF through orthogonal experiment design in this study.Cellulase mixture(Celluclast 1.5 1 and β-glucosidase Novozym 188)were adopted in combination with the yeast Saccharomyces cerevisiae AS2.1.The effects of reaction temperature,substrate concentration,initial fermentation liquid pH value and enzyme loading were evaluated and the SSF conditions were optimized.The ranking,from high to low,of influential extent of the SSF affecting factors to ethanol concentration and yield was substrate concentration,enzyme loading,initial fermentation liquid pH value and reaction temperature,respectively.The optimal SSF conditions were:reaction temperature,35℃;substrate concentration,100 g·L^(-1);initial fermentation liquid pH,5.0;enzyme loading,30 FPU·g21.Under these conditions,the ethanol concentration increased with reaction time,and after 72 h,ethanol was obtained in 65.8%yield with a concentration of 22.7 g·L^(-1).展开更多
To save the cost and input energy for bioethanol production, a consolidated continuous solid-state fermentation (CCSSF) system composed of a rotating drum reactor, a humidifier and a condenser has been developed. In t...To save the cost and input energy for bioethanol production, a consolidated continuous solid-state fermentation (CCSSF) system composed of a rotating drum reactor, a humidifier and a condenser has been developed. In this research, the feasibility of using this system for production of ethanol from food wastes was carried out. The ethanol conversion of bread crust and rice grain (uncooked rice) as substrates reached up to 100.9% ± 5.1% and 108.0% ± 7.9% (against theoretical yield), respectively. Even for bread crust, a processed starchy material which contained lower carbohydrate content than rice grain, the amount of ethanol obtained in a unit of CCSSF per year was higher due to easy saccharification and fermentation. The salt contained in potato chips directly affected yeast activity resulting to low ethanol conversion (80.7% ± 4.7% against theoretical yield).展开更多
基金Supported by National Science and Technology Key Project of Water Pollution Control and Management(2009ZX07101-015-03)
文摘[ Objective] The research aimed to explore the efficiency of ethanol production under the optimal conditions of separate hydrolysis and fermentation （SHF） and simultaneous saccharification and fermentation （SSF）. [ Method ] Under the optimal conditions of hydrolysis and fermenta- tion, SHF and SSF process were designed respectively. SHF process was conducted under the optimal conditions of hydrolysis and fermentation separately, while SSF process was carried out at the optimum temperature of hydrolysis and fermentation. [ Result] In SHF process, the efficiency of ethanol production was similar during both supematant and mixture fermentation, and yeast was more active during the mixture fermentation. In SSF process, the efficiency of ethanol production was higher at 35 ℃, and the production of xylose was higher than that in hydrolysis process. [ Conclusion] Under the experimental conditions, the efficiency of ethanol production during simultaneous saccharification and fermentation was higher than that during separate hydrolysis and fermentation.
文摘Lespedeza stalks were subjected to steam pretreatment at 210℃ for some steaming time before simultaneous saccharification and fermentation （SSF）. Cellulose-derived glucose was extensively utilized by yeast during SSE The ethanol yields after steam pretreatment of the lespedeza stalks at 210℃ were 59.3%, 72.8% and 62.2% of the theoretically expected values when the steaming times were 2, 4 and 6 min, respectively. The highest yield from α-cellulose was 92.7% of the theoretical value. Steam explosion pretreatment of lespedeza stalks increased ethanol yields by a factor of 4.4, from 16.4% （untreated） to 72.8% （steam explosion pretreated）.
基金Supported by the National Natural Science Foundation of China(21276111,21206053,61305017)the Programme of Introducing Talents of Discipline to Universities(B12018)+2 种基金Fundamental Research Funds for the Central Universities(JUSRP11558)the Natural Science Foundation of Jiangsu Province(no.BK20160162)the Fundamental Research Funds for the Central Universities(JUSRP51510)
文摘Chinese rice wine making is a typical simultaneous saccharification and fermentation （SSF） process. During the fermentation process, temperature is one of the key parameters which decide the quality of Chinese rice wine. To optimize the SSF process for Chinese rice wine brewing, the effects of temperature on the kinetic parameters of yeast growth and ethanol production at various temperatures were determined in batch cultures using a mathematical model. The kinetic parameters as a function of temperature were evaluated using the software Origin8.0. Combing these functions with the mathematical model, an appropriate form of the model equations for the SSF considering the effects of temperature were developed. The kinetic parameters were found to fit the experimental data satisfactorily with the developed temperature-dependent model. The temperature profile for maximizing the ethanol production for rice wine fermentation was determined by genetic algorithm. The optimum temperature profile began at a low temperature of 26℃ up to 30 h. The operating temperature increased rapidly to 31.9 ℃, and then decreased slowly to 18℃ at 65 h. Thereafter, the temperature was maintained at 18 ℃ until the end of fermentation. A maximum ethanol production of 89.3 g.L 1 was attained. Conceivably, our model would facilitate the improvement of Chinese rice wine production at the industrial scale.
文摘The effects of process variables in Simultaneous Saccharification and Fermentation (SSF) of wheat bran flour were studied in bulk fermentation using a coculture of Aspergillus niger - Kluveromyces marxianus. The effect of substrate density, pH, temperature, and enzyme concentration on wheat bran was predicted by designing experiments in which a single parameter is varied keeping other variables at a constant level. The above parameters were optimized for a batch culture in a fermentor. Optimal values for substrate concentration, pH, temperature, and enzyme concentration during processing were 200 g/l, 5.5, 65°C, and 7.5 IU, respectively. In pre-treatment experiments, the concentration of enzymes and the pre-treatment temperature are highly correlated. The influence of pH, temperature, and substrate density on ethanol production was investigated. Temperature pH was determined as optimal, 32°C and 5.5, respectively. After 48 hours of fermentation at optimum pH, a solution of wheat bran containing a maximum of 6% starch produces a maximum of 22.9 g/l ethanol.
文摘The Simultaneous Saccharification and Fermentation （SSF） of alkali-acid pretreated sugarcane trash to ethanol was optimized using commercial cellulase and Saccharomyces cerevisiae TISTR 5596 cells. Substrate concentration （12.5% w/v, 15% w/v, 17.5% w/v and 20% w/v）, enzyme loading （25 FPU/g Dry Substrate （DS）, 50 FPU/g DS and 75 FPU/g DS）, and temperature （30 ~C, 35 ~C and 40 ~C） were evaluated. The SSF optimal conditions for alkali-acid pretreated sugarcane trash were 20% w/v of substrate concentration, enzyme loading 50 FPU/g DS, temperature 35 ~C, initial pH 5.0 and yeast inoculum 107 cells/mL. Under the above optimal conditions, ethanol concentration was possible to reach in the range between 50.14 g/L and 55.08 g/L at 96 hrs and 144 hrs, respectively. This study could establish the effective utilization of sugarcane trash for bioethanol production using optimized fermentation parameters.
文摘Studies on simultaneous saccharification and fermentation(SSF)of wheat bran flour,a grain milling residue as the substrate using coculture method were carried out with strains of starch digesting Aspergillus niger and nonstarch digesting and sugar fermenting Kluyveromyces marxianus in batch fermentation.Experi-ments based on central composite design(CCD)were conducted to maximize the glucose yield and to study the effects of substrate concentration,pH,temperature,and enzyme concentration on percentage conversion of wheat bran flour starch to glucose by treatment with fungalα-amylase and the above parameters were optimized using response surface methodology(RSM).The optimum values of substrate concentration,pH,temperature,and enzyme concentration were found to be 200g/L,5.5,65℃ and 7.5IU,respectively,in the starch saccharification step.The effects of pH,temperature and substrate concentration on ethanol concentration,biomass and reducing sugar concentration were also investigated.The optimum temperature and pH were found to be 30℃ and 5.5,respectively.The wheat bran flour solution equivalent to 6%(w/V)initial starch concentration gave the highest ethanol concentrationof 23.1g/Lafter 48hoffermentation at optimum conditions of pH and temperature.The growth kinetics was modeled using Monod model and Logistic model and product formation kinetics using Leudeking-Piret model.Simultaneous saccharificiation and fermenta-tion of liquefied wheat bran starch to bioethanol was studied using coculture of amylolytic fungus A.niger and nonamylolytic sugar fermenting K.marxianus.
基金financial support from the National Natural Science Foundation of China(Grant No.20736006)the National Basic Research Program of China(Grant No.2007CB714301)+1 种基金the international collaboration project of MOST(2006DFA62400)Key Projects in the National Science&Technology Pillar Program(No.2007BAD42B02).
文摘Due to its merits of drought tolerance and high yield,sweet potatoes are widely considered as a potential alterative feedstock for bioethanol production.Very high gravity(VHG)technology is an effective strategy for improving the efficiency of ethanol fermentation from starch materials.However,this technology has rarely been applied to sweet potatoes because of the high viscosity of their liquid mash.To overcome this problem,cellulase was added to reduce the high viscosity,and the optimal dosage and treatment time were 8 U/g(sweet potato powder)and 1 h,respectively.After pretreatment by cellulase,the viscosity of the VHG sweet potato mash(containing 284.2 g/L of carbohydrates)was reduced by 81%.After liquefaction and simultaneous saccharification and fer-mentation(SSF),thefinal ethanol concentration reached 15.5%(v/v),and the total sugar conversion and ethanol yields were 96.5%and 87.8%,respectively.
文摘Although simultaneous saccharification and fermentation(SSF)has been investigated extensively,the optimum condition for SSF of wheat straw has not yet been determined.Dilute sulfuric acid impregnated and steam explosion pretreated wheat straw was used as a substrate for the production of ethanol by SSF through orthogonal experiment design in this study.Cellulase mixture(Celluclast 1.5 1 and β-glucosidase Novozym 188)were adopted in combination with the yeast Saccharomyces cerevisiae AS2.1.The effects of reaction temperature,substrate concentration,initial fermentation liquid pH value and enzyme loading were evaluated and the SSF conditions were optimized.The ranking,from high to low,of influential extent of the SSF affecting factors to ethanol concentration and yield was substrate concentration,enzyme loading,initial fermentation liquid pH value and reaction temperature,respectively.The optimal SSF conditions were:reaction temperature,35℃;substrate concentration,100 g·L^(-1);initial fermentation liquid pH,5.0;enzyme loading,30 FPU·g21.Under these conditions,the ethanol concentration increased with reaction time,and after 72 h,ethanol was obtained in 65.8%yield with a concentration of 22.7 g·L^(-1).
文摘To save the cost and input energy for bioethanol production, a consolidated continuous solid-state fermentation (CCSSF) system composed of a rotating drum reactor, a humidifier and a condenser has been developed. In this research, the feasibility of using this system for production of ethanol from food wastes was carried out. The ethanol conversion of bread crust and rice grain (uncooked rice) as substrates reached up to 100.9% ± 5.1% and 108.0% ± 7.9% (against theoretical yield), respectively. Even for bread crust, a processed starchy material which contained lower carbohydrate content than rice grain, the amount of ethanol obtained in a unit of CCSSF per year was higher due to easy saccharification and fermentation. The salt contained in potato chips directly affected yeast activity resulting to low ethanol conversion (80.7% ± 4.7% against theoretical yield).
