Effects of Chemical Pretreatment on Enzymatic Saccharification and Fermentation of Forages

[ Objective] To study the effect of pretreatment with chemical substances on enzymatic saccharification of affalfa （ Medic, ago sativa L. ）, sorghum hybrid sudan grass [ Sorghum bicolor （ L. ） Moench x Sorghum sudanese （Piper） Stapf], erect milkvetch （Astraga/us adsurgens Pall. ） and pearl millet （ Pennisetum americanum （ L. ） Leeke）. [ Method ] The forages were pretreated with sulfuric acid at different concentration, and then the content of cellulose, hemicellulose, and lignin were detected and compared with that before pretreatment. The concentration of glucose and ethanol after different fermentation time was also determined. [ Result] After pretreatment, the content of cellulose increased, while that of hemicel- lulose and lignin decreased. After treatment with 1.0% （W/V） sulfuric acid, the four kinds of forages all had the highest concentration of ethanol in the citric acid-sodium citrate buffer system （pH 4.8）. Dudng fermentation process, the concentration of glucose and ethanol first increased and then declined, peaking respectively at 24 h and 48 h post fermentation. [Condusion] Pretreatment promotes the enzymatic saccharification and fermen- tation of alfalfa, sorehum hvbrid sudan orass. Dead millet, and erect milkvetch, and their enerov performance decreases in order.

Optimization of rice wine fermentation process based on the simultaneous saccharification and fermentation kinetic model

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.

Simultaneous saccharification and fermentation of steam-pretreated lespedeza stalks for the production of ethanol

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）.

Simultaneous Saccharification and Fermentation of Alkali-Acid Pretreated Sugarcane Trash to Ethanol

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.

Optimization Studies in Simultaneous Saccharification and Fermentation of Wheat Bran Flour into Ethanol

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.

Process Research on Separate Hydrolysis and Fermentation(SHF) and Simultaneous Saccharification and Fermentation(SSF) of Ethanol Production by Lignocellulose

[ 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.

Simultaneous saccharification and fermentation of sweet potato powder for the production of ethanol under conditions of very high gravity

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.

Study of simultaneous saccharification and fermentation for steam exploded wheat straw to ethanol

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).