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）.

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).