[ 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 sud...[ 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.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
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
Reliable production of biofuels and specifically bioethanol has attracted a significant amount of re-search recently.Within this context,this study deals with dynamic simulation of bioethanol production processes and ...Reliable production of biofuels and specifically bioethanol has attracted a significant amount of re-search recently.Within this context,this study deals with dynamic simulation of bioethanol production processes and in particular aims at developing a mathematical model for describing simultaneous saccharification and co-fermentation （SSCF） of C6 and C5 sugars.The model is constructed by combining existing mathematical mod-els for enzymatic hydrolysis and co-fermentation.An inhibition of ethanol on cellulose conversion is introduced in order to increase the reliability.The mathematical model for the SSCF is verified by comparing the model predic-tions with experimental data obtained from the ethanol production based on kraft paper mill sludge.When fitting the model to the data,only the yield coefficients for glucose and xylose metabolism were fine-tuned,which were found to be 0.43 g·g-1 （ethanol/glucose） and 0.35 g·g-1 （ethanol/xylose） respectively.These promising validation results encourage further model application to evaluate different process configurations for lignocellulosic bioetha-nol technology.展开更多
Lignocellulosic materials are promising alternative feedstocks for bioethanol production. However, the recalcitrant nature of lignocellulosic biomass necessitates an efficient pretreatment pretreatment step to improve...Lignocellulosic materials are promising alternative feedstocks for bioethanol production. However, the recalcitrant nature of lignocellulosic biomass necessitates an efficient pretreatment pretreatment step to improve the yield of fermentable sugars and maximizing the enzymatic hydrolysis efficiency. Microwave pretreatment may be a good alternative as it can reduce the pretreatment time and improve the enzymatic activity during hydrolysis. The overall goal of this paper is to expand the current state of knowledge on microwave-based pretreatment of lignocellulosic biomass and microwave assisted enzymatic reaction or Microwave Irradiation-Enzyme Coupling Catalysis (MIECC). In the present study, a comparison of microwave assisted alkali pretreatment was tried using Oil Palm empty fruit bunch. The microwave assisted alkali pretreatment of EFB using NaOH, significantly improved the enzymatic saccharification of EFB by removing more lignin and hemicellulose and increasing its accessibility to hydrolytic enzymes. The results showed that the optimum pretreatment condition was 3% (w/v) NaOH at 180 W for 12 minutes with the optimum component loss of lignin and holocellulose of about 74% and 24.5% respectively. The subsequent enzymatic saccharification of EFB pretreated by microwave assisted NaOH (3% w/v);resulted in 411 mg of reducing sugar per gram EFB at cellulose enzyme dosage of 20 FPU. The overall enhancement by the microwave treatment during the microwave assisted alkali pretreatment and microwave assisted enzymatic hydrolysis was 5.8 fold. The present study has highlighted the importance of well controlled microwave assisted enzymatic reaction to enhance the overall reaction rate of the process.展开更多
A simple and efficient method of enhancing biomass saccharification by microwave-assisted pretreatment with dimethyl sulfoxide/1-allyl-3-methylimidazolium chloride is proposed. Softwood（pine wood（PW））, hardwoods（...A simple and efficient method of enhancing biomass saccharification by microwave-assisted pretreatment with dimethyl sulfoxide/1-allyl-3-methylimidazolium chloride is proposed. Softwood（pine wood（PW））, hardwoods（poplar wood, catalpa bungi, and Chinese parasol）, and agricultural wastes（rice straw, wheat straw, and corn stover（CS）） were exploited. Results showed that the best pretreatment effect was in PW with 54.3% and 31.7% dissolution and extraction ratios, respectively. The crystal form of cellulose in PW extract transformed from I to II, and the contended cellulose ratio and glucose conversion ratio reached 85.1% and 85.4%, respectively. CS after steam explosion achieved a similar pretreating effect as PW, with its cellulose hydrolysis ratio reaching as high as 91.5% after IL pretreatment.展开更多
Development of strategies to deconstruct lignocellulosic biomass in tree species is essential for biofuels and biomaterials production.We applied a wood forming tissue-specific system in a hybrid poplar to express bot...Development of strategies to deconstruct lignocellulosic biomass in tree species is essential for biofuels and biomaterials production.We applied a wood forming tissue-specific system in a hybrid poplar to express both PdSuSy(a sucrose synthase gene from Populus deltoides×P.euramericana that has not been functionally characterized)and HCHL(the hydroxycinnamoyl-CoA hydratase-lyase gene from Pseudomonas fluorescens,which inhibits lignin polymerization in Arabidopsis).The PdSuSy-HCHL overexpression poplars correspondingly driven by the promoters of Arabidopsis AtCesA7 and AtC4 H resulted in a significant increase in cellulose(>8%),xylan(>12%)and glucose(>29%)content,accompanying a reduction in galacturonic acid(>36%)content,compared to control plants.The saccharification efficiency of these overexpression poplars was dramatically increased by up to 27%,but total lignin content was unaffected.These transgenic poplars showed inhibited growth characteristics,including>16%reduced plant height,>10% reduced number of internodes,and>18% reduced fresh weight after growth of 4 months,possibly due to relatively low expression of HCHL in secondary xylem.Our results demonstrate the structural complexity and interaction of the cell wall polymers in wood tissue and outline a potential method to increase biomass saccharification in woody species.展开更多
In this paper three methods(dilute acid pretreatment, aqueous ammonia/dilute acid pretreatment and alkaline pretreatment) were used to study the hydrolysis of corn stover and characteristics of each method were compar...In this paper three methods(dilute acid pretreatment, aqueous ammonia/dilute acid pretreatment and alkaline pretreatment) were used to study the hydrolysis of corn stover and characteristics of each method were compared. The results showed that the lignin removal rate was 71.8% when the corn stover was treated with a caustic soda solution containing 1.5% of NaOH, at a temperature of 75 ℃ for 90 min with an initial solid-liquid ratio of 1:8(w/v). Hydrolysis yield of the NaOH pretreated sample reached 78.5%, which was much higher than other control groups. These results are useful for evaluation of pretreatment technologies, and identification of key factors that limit cellulose hydrolysis, and can also serve as a basis for designing and screening appropriate pretreatment technologies.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
Sugarcane shoots and leaves consist of 35.2% cellulose, 23.43% hemicellulose, 12.6% lignin and 6.59% ash on dry solid （DS） basis and have the potential to serve as low cost feedstocks for ethanol production. To impr...Sugarcane shoots and leaves consist of 35.2% cellulose, 23.43% hemicellulose, 12.6% lignin and 6.59% ash on dry solid （DS） basis and have the potential to serve as low cost feedstocks for ethanol production. To improve the enzymatic digestibility of these biomass and bioethanol production, three pretreatment methods had been investigated and compared, including： （1） 2% w/v NaOH solution autoclaving pretreatment; （2） 2% w/v H2SO4 solution autoclaving pretreatment and （3） two steps of 2% w/v NaOH solution autoclaving followed by 2% w/v H2SO4 solution autoclaving pretreatment. Among them, the best result for ethanol production was obtained when 15 g DS of sugarcane shoots and leaves was pretreated by using two step of 2% w/v NaOH solution autoclaving followed by 2% w/v H2SO4 solution autoclaving. The highest ethanol concentration 30.40 g/L （92.65% in fermentation efficiency） was obtained from reducing sugar 89.25 g/L at 48 h. Moreover, the washing step of solid residue after pretreatment could reduce furfural and hydroxymethylfurfural （HMF） in all pretreatment methods when compared to unwashing solid residue after pretreatment.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
[ Objective] The aim was to improve the saccharification of wheat bran cellulose. [ Method] Taking the wheat bran as raw materials, and using orthogonal method, the effects of acid concentration, temperature, times an...[ Objective] The aim was to improve the saccharification of wheat bran cellulose. [ Method] Taking the wheat bran as raw materials, and using orthogonal method, the effects of acid concentration, temperature, times and substrate concentration on the saccharification were investigated. [ Result] The influence of temperature on the acid treatment of the sacchadfication of wheat bran cellulose was significant. Influences of acid concentration on the hydrolysis were distinct. Influences of time and substrate concentration were insignificant. The optimal pretreatment conditions were 1.5% of sulfuric acid concentration and 0. 067 g/ml of substrate concentration at 100℃ in three hours. Under this condition, the sugar concentration was 38.137 mg/ml, and the hydrolysis rate reached 51.485%. [ Conclusion] The study improved the saccharification of wheat bran cellulose, which provided theoretical basis for the application of wheat bran industrial process.展开更多
[ 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
The aim of this study was to establish a control system for saccharification process using quality control charts. To achieve this goal, temperature, pH and brix were measured at 12 minutes intervals for 15 consecutiv...The aim of this study was to establish a control system for saccharification process using quality control charts. To achieve this goal, temperature, pH and brix were measured at 12 minutes intervals for 15 consecutive batches which took 2 hours each. The time variations for three process parameters were assessed to establish a good understanding of the saccharification process. The temperature varied between 58℃ and 62℃ while the pH decreased slowly due to oxidation, values of which varied between 5.7 and 5.0. Brix values increased linearly with time. The initial and final values of the three parameters varied from one batch to another. Of the three parameters, brix was not well represented on the quality control charts due to wide difference between initial and final values during saccharification. The final brix values varied between batches, from 10.6% to 11.6%. The control charts used in this study were X-bar and Range charts. The rules for interpreting control charts were implemented for both X-bar and R charts, results of which showed that the process was out of control, although some rules were not violated due to little number of batches studied. The values of for temperature and pH data (2.27℃ and 0.35, respectively) were lower compared to brix data (11.2%). The corresponding values of span between control limits, SP<sub>x</sub> and SP<sub>R</sub> for temperature and pH were also comparatively lower than those established from brix data. Due to larger values of for brix measurements, the corresponding control charts for brix were insensitive in identifying out-of-control points during saccharification process.展开更多
Hierarchically structured macro-mesoporous carbon catalysts were synthesized using dual templates of poly(methyl methacrylate)(PMMA)and Pluronic-123 to enhance cellulose saccharification.Characterizations conducted th...Hierarchically structured macro-mesoporous carbon catalysts were synthesized using dual templates of poly(methyl methacrylate)(PMMA)and Pluronic-123 to enhance cellulose saccharification.Characterizations conducted through scanning electron microscopy(SEM),X-ray diffraction(XRD),N2 adsorption-desorption isotherms,Fourier transform infrared(FT-IR)spectroscopy,and titration techniques confirmed high surface areas and specific pore size distributions,with macropores ranging from 78.3 to 251 nm and mesopores around 2.43-6.23 nm.An optimal PMMA-to-Tetraethyl orthosilicate(TEOS)ratio of 1:1.6 facilitated the highest cellulose conversion rate of 59.3%and a glucose yield of 22.1%.Notably,the medium-sized macropore catalyst,MMCS60-M,outperformed its purely mesoporous counterpart,with conversion rates and glucose yields of 80.8% and 45.5%,respectively.These results suggest the importance of a tailored pore architecture to enhance the accessibility of acid sites and facilitate effective mass transport,which is beneficial for optimizing saccharification processes.展开更多
The aim of this work was to study the efficiency of native lignocellulolytic enzymes obtained from isolated bacteria towards enhanced bioethanol production from lignocellulosic biomass.Maximum cellulose(199.33±0....The aim of this work was to study the efficiency of native lignocellulolytic enzymes obtained from isolated bacteria towards enhanced bioethanol production from lignocellulosic biomass.Maximum cellulose(199.33±0.2 mg/g)and hemicellulose(62.21±0.22 mg/g)content was measured from rice straw in alkali condition compared to acid and biological pretreatment,while significant lignin removal has been observed in biological pretreatment.Saccharification of rice straw using isolated cellulase–xylanase enzymes exhibited 60.33%production of total reducing sugar obtained by commercial cellulase–xylanase cocktail.Maximum glucose,xylose,and total reducing sugar yield of 309±0.32,190.7±0.42,and 499.7±0.37 mg/g,respec-tively,at 37.5℃,pH-7,rice straw concentration of 2.5 g/100 mL,enzyme loading 175μl,and incubation period 42 h by com-mercial cellulase–xylanase enzyme mediated hydrolysis.While in case of using the native cellulase–xylanase cocktail from the isolated bacterial strains,highest yields of glucose,xylose and total reducing sugar production was 253.52±0.56 mg/g,47.94±0.78 mg/g,and 301.46±0.67 mg/g,respectively.While applying the isolated enzymes on alkali-pretreated rice straw,bioethanol concentration of around 32.57±0.25 g/L was recorded after the simultaneous saccharification and fermentation by Saccharomyces cerevisiae.The above mentioned bioethanol concentration was obtained at a process parameter of temperature 35℃,incubation time 58 h,and pH 5.5 for isolated cellulase–xylanase enzymes.A maximum bioethanol concentration using isolated cellulase–xylanase enzymes was nearly 93.89%of bioethanol concentration(34.69±0.28 g/L)obtained using commercial cellulase–xylanase.The present study interpreted that the cutting-edge approach for the native enzymes along with metabolic engineering of the isolated bacteria could be promising towards enhanced bioethanol production.展开更多
In the present study,a sustainable pretreatment methodology combining liquid hot water and deep eutectic solvent is proposed for the efficient fractionation of hemicellulose,cellulose,and lignin from sugarcane bagasse...In the present study,a sustainable pretreatment methodology combining liquid hot water and deep eutectic solvent is proposed for the efficient fractionation of hemicellulose,cellulose,and lignin from sugarcane bagasse,thereby facilitating the comprehensive utilization of both C5 and C6 sugars.The application of this combined pretreatment strategy to sugarcane bagasse led to notable enhancements in enzymatic saccharification and subsequent fermentation.Experiment results demonstrate that liquid hot water-deep eutectic solvent pretreatment yielded 85.05±0.66 g·L^(-1)of total fermentable sugar(glucose:60.96±0.21 g·L^(-1),xylose:24.09±0.87 g·L^(-1))through enzymatic saccharification of sugarcane bagasse.Furthermore,fermentation of the pretreated sugarcane bagasse hydrolysate yielded 34.33±3.15 g·L^(-1)of bioethanol.These findings confirm the effectiveness of liquid hot water-deep eutectic solvent pretreatment in separating lignocellulosic components,thus presenting a sustainable and promising pretreatment method for maximizing the valuable utilization of biomass resources.展开更多
Aqua-ammonia pretreatment of corn stover was provided in a 1.2 L high pressure reactor with two ammonia:biomass ratios of 1:1(w/w)and 2:1(w/w);at three temperatures:60℃,90℃and 120℃,and two treatment time:5 min and ...Aqua-ammonia pretreatment of corn stover was provided in a 1.2 L high pressure reactor with two ammonia:biomass ratios of 1:1(w/w)and 2:1(w/w);at three temperatures:60℃,90℃and 120℃,and two treatment time:5 min and 30 min.Pretreatment with water was used as control.The pretreated samples were saccharified to fermentable sugars by commercial enzymes ACCELERASE 1500(cellulase)and ACCELERASE XC(xylanases).For ammonia:biomass ratio of 1:1,the yield of total fermentable sugar was 87%at 90℃for 30 min treatment.In case of ammonia:biomass ratio of 2:1,fermentable sugar yield increased four fold of that of control.Maximum fermentable sugar yield of 99%was obtained for 2:1 ammonia:biomass ratio,90℃,and 30 min treatment time.The results of this study are very promising for improving fermentable sugar yield from corn stover using smaller amount of ammonia than the ammonia fiber explosion and other pretreatments such as strong acid or alkali pretreatments.However,further optimization is required for reducing pretreatment time.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
文摘[ 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.
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 Mexican National Council for Science and Technology (CONACyT# 118903)the Danish Research Council for Technology and Production Sciences (FTP# 274-07-0339)
文摘Reliable production of biofuels and specifically bioethanol has attracted a significant amount of re-search recently.Within this context,this study deals with dynamic simulation of bioethanol production processes and in particular aims at developing a mathematical model for describing simultaneous saccharification and co-fermentation （SSCF） of C6 and C5 sugars.The model is constructed by combining existing mathematical mod-els for enzymatic hydrolysis and co-fermentation.An inhibition of ethanol on cellulose conversion is introduced in order to increase the reliability.The mathematical model for the SSCF is verified by comparing the model predic-tions with experimental data obtained from the ethanol production based on kraft paper mill sludge.When fitting the model to the data,only the yield coefficients for glucose and xylose metabolism were fine-tuned,which were found to be 0.43 g·g-1 （ethanol/glucose） and 0.35 g·g-1 （ethanol/xylose） respectively.These promising validation results encourage further model application to evaluate different process configurations for lignocellulosic bioetha-nol technology.
文摘Lignocellulosic materials are promising alternative feedstocks for bioethanol production. However, the recalcitrant nature of lignocellulosic biomass necessitates an efficient pretreatment pretreatment step to improve the yield of fermentable sugars and maximizing the enzymatic hydrolysis efficiency. Microwave pretreatment may be a good alternative as it can reduce the pretreatment time and improve the enzymatic activity during hydrolysis. The overall goal of this paper is to expand the current state of knowledge on microwave-based pretreatment of lignocellulosic biomass and microwave assisted enzymatic reaction or Microwave Irradiation-Enzyme Coupling Catalysis (MIECC). In the present study, a comparison of microwave assisted alkali pretreatment was tried using Oil Palm empty fruit bunch. The microwave assisted alkali pretreatment of EFB using NaOH, significantly improved the enzymatic saccharification of EFB by removing more lignin and hemicellulose and increasing its accessibility to hydrolytic enzymes. The results showed that the optimum pretreatment condition was 3% (w/v) NaOH at 180 W for 12 minutes with the optimum component loss of lignin and holocellulose of about 74% and 24.5% respectively. The subsequent enzymatic saccharification of EFB pretreated by microwave assisted NaOH (3% w/v);resulted in 411 mg of reducing sugar per gram EFB at cellulose enzyme dosage of 20 FPU. The overall enhancement by the microwave treatment during the microwave assisted alkali pretreatment and microwave assisted enzymatic hydrolysis was 5.8 fold. The present study has highlighted the importance of well controlled microwave assisted enzymatic reaction to enhance the overall reaction rate of the process.
基金supported by the National Natural Science Foundation of China(No.21006118)the National High Technology Research and Development Program of China(863Project,Nos.2012AA101807 and 2012AA022301)
文摘A simple and efficient method of enhancing biomass saccharification by microwave-assisted pretreatment with dimethyl sulfoxide/1-allyl-3-methylimidazolium chloride is proposed. Softwood（pine wood（PW））, hardwoods（poplar wood, catalpa bungi, and Chinese parasol）, and agricultural wastes（rice straw, wheat straw, and corn stover（CS）） were exploited. Results showed that the best pretreatment effect was in PW with 54.3% and 31.7% dissolution and extraction ratios, respectively. The crystal form of cellulose in PW extract transformed from I to II, and the contended cellulose ratio and glucose conversion ratio reached 85.1% and 85.4%, respectively. CS after steam explosion achieved a similar pretreating effect as PW, with its cellulose hydrolysis ratio reaching as high as 91.5% after IL pretreatment.
基金funded by National Key Program on Transgenic Research(2018ZX08020002)National Key Scientific Research Project of China(2016YFD0600104)+3 种基金National Natural Science Foundation of China(31670606,31570670,31770315 and 31701068)Major Basic Research Project of Shandong Natural Science Foundation(ZR2018ZC0335)Shandong Provincial Natural Science Foundation(ZR2017BC096 and ZR2017BC078)Taishan Scholar Program of Shandong(to G.Z.)。
文摘Development of strategies to deconstruct lignocellulosic biomass in tree species is essential for biofuels and biomaterials production.We applied a wood forming tissue-specific system in a hybrid poplar to express both PdSuSy(a sucrose synthase gene from Populus deltoides×P.euramericana that has not been functionally characterized)and HCHL(the hydroxycinnamoyl-CoA hydratase-lyase gene from Pseudomonas fluorescens,which inhibits lignin polymerization in Arabidopsis).The PdSuSy-HCHL overexpression poplars correspondingly driven by the promoters of Arabidopsis AtCesA7 and AtC4 H resulted in a significant increase in cellulose(>8%),xylan(>12%)and glucose(>29%)content,accompanying a reduction in galacturonic acid(>36%)content,compared to control plants.The saccharification efficiency of these overexpression poplars was dramatically increased by up to 27%,but total lignin content was unaffected.These transgenic poplars showed inhibited growth characteristics,including>16%reduced plant height,>10% reduced number of internodes,and>18% reduced fresh weight after growth of 4 months,possibly due to relatively low expression of HCHL in secondary xylem.Our results demonstrate the structural complexity and interaction of the cell wall polymers in wood tissue and outline a potential method to increase biomass saccharification in woody species.
基金Financial support provided by the SINOPEC Research Program(No.S213070)
文摘In this paper three methods(dilute acid pretreatment, aqueous ammonia/dilute acid pretreatment and alkaline pretreatment) were used to study the hydrolysis of corn stover and characteristics of each method were compared. The results showed that the lignin removal rate was 71.8% when the corn stover was treated with a caustic soda solution containing 1.5% of NaOH, at a temperature of 75 ℃ for 90 min with an initial solid-liquid ratio of 1:8(w/v). Hydrolysis yield of the NaOH pretreated sample reached 78.5%, which was much higher than other control groups. These results are useful for evaluation of pretreatment technologies, and identification of key factors that limit cellulose hydrolysis, and can also serve as a basis for designing and screening appropriate pretreatment technologies.
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Sugarcane shoots and leaves consist of 35.2% cellulose, 23.43% hemicellulose, 12.6% lignin and 6.59% ash on dry solid （DS） basis and have the potential to serve as low cost feedstocks for ethanol production. To improve the enzymatic digestibility of these biomass and bioethanol production, three pretreatment methods had been investigated and compared, including： （1） 2% w/v NaOH solution autoclaving pretreatment; （2） 2% w/v H2SO4 solution autoclaving pretreatment and （3） two steps of 2% w/v NaOH solution autoclaving followed by 2% w/v H2SO4 solution autoclaving pretreatment. Among them, the best result for ethanol production was obtained when 15 g DS of sugarcane shoots and leaves was pretreated by using two step of 2% w/v NaOH solution autoclaving followed by 2% w/v H2SO4 solution autoclaving. The highest ethanol concentration 30.40 g/L （92.65% in fermentation efficiency） was obtained from reducing sugar 89.25 g/L at 48 h. Moreover, the washing step of solid residue after pretreatment could reduce furfural and hydroxymethylfurfural （HMF） in all pretreatment methods when compared to unwashing solid residue after pretreatment.
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.
基金Supported by National Natural Fund Program(31071636)Anhui Science and Technology Bureau Program(1206C0805017/KJ2010A262)
文摘[ Objective] The aim was to improve the saccharification of wheat bran cellulose. [ Method] Taking the wheat bran as raw materials, and using orthogonal method, the effects of acid concentration, temperature, times and substrate concentration on the saccharification were investigated. [ Result] The influence of temperature on the acid treatment of the sacchadfication of wheat bran cellulose was significant. Influences of acid concentration on the hydrolysis were distinct. Influences of time and substrate concentration were insignificant. The optimal pretreatment conditions were 1.5% of sulfuric acid concentration and 0. 067 g/ml of substrate concentration at 100℃ in three hours. Under this condition, the sugar concentration was 38.137 mg/ml, and the hydrolysis rate reached 51.485%. [ Conclusion] The study improved the saccharification of wheat bran cellulose, which provided theoretical basis for the application of wheat bran industrial process.
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The aim of this study was to establish a control system for saccharification process using quality control charts. To achieve this goal, temperature, pH and brix were measured at 12 minutes intervals for 15 consecutive batches which took 2 hours each. The time variations for three process parameters were assessed to establish a good understanding of the saccharification process. The temperature varied between 58℃ and 62℃ while the pH decreased slowly due to oxidation, values of which varied between 5.7 and 5.0. Brix values increased linearly with time. The initial and final values of the three parameters varied from one batch to another. Of the three parameters, brix was not well represented on the quality control charts due to wide difference between initial and final values during saccharification. The final brix values varied between batches, from 10.6% to 11.6%. The control charts used in this study were X-bar and Range charts. The rules for interpreting control charts were implemented for both X-bar and R charts, results of which showed that the process was out of control, although some rules were not violated due to little number of batches studied. The values of for temperature and pH data (2.27℃ and 0.35, respectively) were lower compared to brix data (11.2%). The corresponding values of span between control limits, SP<sub>x</sub> and SP<sub>R</sub> for temperature and pH were also comparatively lower than those established from brix data. Due to larger values of for brix measurements, the corresponding control charts for brix were insensitive in identifying out-of-control points during saccharification process.
文摘Hierarchically structured macro-mesoporous carbon catalysts were synthesized using dual templates of poly(methyl methacrylate)(PMMA)and Pluronic-123 to enhance cellulose saccharification.Characterizations conducted through scanning electron microscopy(SEM),X-ray diffraction(XRD),N2 adsorption-desorption isotherms,Fourier transform infrared(FT-IR)spectroscopy,and titration techniques confirmed high surface areas and specific pore size distributions,with macropores ranging from 78.3 to 251 nm and mesopores around 2.43-6.23 nm.An optimal PMMA-to-Tetraethyl orthosilicate(TEOS)ratio of 1:1.6 facilitated the highest cellulose conversion rate of 59.3%and a glucose yield of 22.1%.Notably,the medium-sized macropore catalyst,MMCS60-M,outperformed its purely mesoporous counterpart,with conversion rates and glucose yields of 80.8% and 45.5%,respectively.These results suggest the importance of a tailored pore architecture to enhance the accessibility of acid sites and facilitate effective mass transport,which is beneficial for optimizing saccharification processes.
文摘The aim of this work was to study the efficiency of native lignocellulolytic enzymes obtained from isolated bacteria towards enhanced bioethanol production from lignocellulosic biomass.Maximum cellulose(199.33±0.2 mg/g)and hemicellulose(62.21±0.22 mg/g)content was measured from rice straw in alkali condition compared to acid and biological pretreatment,while significant lignin removal has been observed in biological pretreatment.Saccharification of rice straw using isolated cellulase–xylanase enzymes exhibited 60.33%production of total reducing sugar obtained by commercial cellulase–xylanase cocktail.Maximum glucose,xylose,and total reducing sugar yield of 309±0.32,190.7±0.42,and 499.7±0.37 mg/g,respec-tively,at 37.5℃,pH-7,rice straw concentration of 2.5 g/100 mL,enzyme loading 175μl,and incubation period 42 h by com-mercial cellulase–xylanase enzyme mediated hydrolysis.While in case of using the native cellulase–xylanase cocktail from the isolated bacterial strains,highest yields of glucose,xylose and total reducing sugar production was 253.52±0.56 mg/g,47.94±0.78 mg/g,and 301.46±0.67 mg/g,respectively.While applying the isolated enzymes on alkali-pretreated rice straw,bioethanol concentration of around 32.57±0.25 g/L was recorded after the simultaneous saccharification and fermentation by Saccharomyces cerevisiae.The above mentioned bioethanol concentration was obtained at a process parameter of temperature 35℃,incubation time 58 h,and pH 5.5 for isolated cellulase–xylanase enzymes.A maximum bioethanol concentration using isolated cellulase–xylanase enzymes was nearly 93.89%of bioethanol concentration(34.69±0.28 g/L)obtained using commercial cellulase–xylanase.The present study interpreted that the cutting-edge approach for the native enzymes along with metabolic engineering of the isolated bacteria could be promising towards enhanced bioethanol production.
基金the National Natural Science Foundation of China for financial support of this research(Grant Nos.21978053,51508547).
文摘In the present study,a sustainable pretreatment methodology combining liquid hot water and deep eutectic solvent is proposed for the efficient fractionation of hemicellulose,cellulose,and lignin from sugarcane bagasse,thereby facilitating the comprehensive utilization of both C5 and C6 sugars.The application of this combined pretreatment strategy to sugarcane bagasse led to notable enhancements in enzymatic saccharification and subsequent fermentation.Experiment results demonstrate that liquid hot water-deep eutectic solvent pretreatment yielded 85.05±0.66 g·L^(-1)of total fermentable sugar(glucose:60.96±0.21 g·L^(-1),xylose:24.09±0.87 g·L^(-1))through enzymatic saccharification of sugarcane bagasse.Furthermore,fermentation of the pretreated sugarcane bagasse hydrolysate yielded 34.33±3.15 g·L^(-1)of bioethanol.These findings confirm the effectiveness of liquid hot water-deep eutectic solvent pretreatment in separating lignocellulosic components,thus presenting a sustainable and promising pretreatment method for maximizing the valuable utilization of biomass resources.
基金This study was financially supported by the Office of Vice Chancellor for Research,SIU Carbondale,via an Interdisciplinary Research Seed Grant.
文摘Aqua-ammonia pretreatment of corn stover was provided in a 1.2 L high pressure reactor with two ammonia:biomass ratios of 1:1(w/w)and 2:1(w/w);at three temperatures:60℃,90℃and 120℃,and two treatment time:5 min and 30 min.Pretreatment with water was used as control.The pretreated samples were saccharified to fermentable sugars by commercial enzymes ACCELERASE 1500(cellulase)and ACCELERASE XC(xylanases).For ammonia:biomass ratio of 1:1,the yield of total fermentable sugar was 87%at 90℃for 30 min treatment.In case of ammonia:biomass ratio of 2:1,fermentable sugar yield increased four fold of that of control.Maximum fermentable sugar yield of 99%was obtained for 2:1 ammonia:biomass ratio,90℃,and 30 min treatment time.The results of this study are very promising for improving fermentable sugar yield from corn stover using smaller amount of ammonia than the ammonia fiber explosion and other pretreatments such as strong acid or alkali pretreatments.However,further optimization is required for reducing pretreatment time.
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.
