Simultaneous saccharification and fermentation of wheat bran flour into ethanol using coculture of amylotic Aspergillus niger and thermotolerant Kluyveromyces marxianus

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. Experiments 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 fungal α-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 200 g/L, 5.5, 65°C and 7.5 IU, 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°C and 5.5, respectively. The wheat bran flour solution equivalent to 6% (w/V) initial starch concentration gave the highest ethanol concentration of 23.1 g/L after 48 h of fermentation 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 fermentation of liquefied wheat bran starch to bioethanol was studied using coculture of amylolytic fungus A. niger and nonamylolytic sugar fermenting K. marxianus.     

橡子粉同步液化糖化产燃料乙醇的发酵条件优化

以除去单宁的橡子粉为原料,应用活性干酵母同步液化糖化发酵(SLSF)制备燃料乙醇,并通过单因素试验和正交试验优化发酵条件。结果表明,同步液化糖化发酵技术适用于橡子粉发酵制备燃料乙醇;发酵的最佳条件为:除去单宁的橡子粉20 g,料液比为1:3(g:mL),淀粉酶100 U/g,糖化酶3 750 U/g,活性干酵母1.50%;在30 ℃静止发酵120 h,发酵液中的乙醇质量浓度达到106.5 g/L,橡子淀粉的乙醇转化率达到89.36 %。采用橡子粉发酵法制备燃料乙醇与以玉米等粮食作物为原料制备的燃料乙醇质量浓度相当,可以替代粮食作物生产燃料乙醇。     

蒸汽爆破麦草同步糖化发酵转化乙醇的研究

近年来对木质生物资源同步糖化发酵转化乙醇的研究较多,但是,麦草同步糖化发酵转化乙醇的最佳工艺条件还未确定。文中采用正交试验设计的方法,对在混合酶(纤维素酶Celluclast 1.5 1,β-葡萄糖苷酶Novozym 188)与酿酒酵母菌作用下,稀硫酸催化的蒸汽爆破麦草原料同步糖化发酵转化乙醇的工艺条件进行研究,详细讨论了反应温度、底物质量浓度、发酵液pH值、纤维素酶浓度对乙醇质量浓度和得率的影响。结果表明,工艺条件对乙醇质量浓度和得率的影响程度由高到低依次为:底物质量浓度、纤维素酶浓度、发酵液pH值、反应温度。最佳工艺条件为反应温度35℃,底物质量浓度100 g/L,发酵液pH值5.0,纤维素酶浓度30 FPU/g。在此条件下,随着反应时间的延长,乙醇质量浓度持续上升。反应72 h后,乙醇质量浓度和得率分别达到22.7 g/L和65.8%。     

甘薯渣发酵乙醇的工艺研究

研究了甘薯渣同步糖化发酵乙醇的最佳工艺条件,考察了不同酵母接种量、水料比、发酵时间和 pH 对甘薯渣发酵乙醇的影响。通过单因素、正交试验,最终确定同步糖化发酵乙醇的最佳条件为：接种量1.4%,水料比25：1,发酵时间108h,pH 5.5。在此条件下乙醇得率为34.78%,糖利用率为73.76%。     

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 l and ?-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°C; substrate concentration, 100 g·L^-1; initial fermentation liquid pH, 5.0; enzyme loading, 30 FPU·g^-1. 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.     

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 l 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°C; substrate concentration, 100 g·L⁻¹; initial fermentation liquid pH, 5.0; enzyme loading, 30 FPU·g⁻¹. 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. __________ Translated from Chemical Engineering (China), 2007, 35(12): 42–45 [译自: 化学工程]     

瘤胃菌与丁醇菌共生发酵麸皮生产丁醇

寻求瘤胃纤维素降解菌群NLH151与丁醇菌zr11共生发酵麸皮生产丁醇的最佳工艺条件。考察了接种方式、共培养温度、pH值等因素对纤维素降解率及丁醇生产能力的影响,得出了2种菌最佳共生培养的发酵条件。共生发酵时,麸皮质量浓度为20 g/L,共培养温度为33℃,pH值为6.0—6.5,瘤胃菌NLH151与丁醇菌zr11的接种量(体积分数)分别控制在15%和8%,瘤胃菌接入24 h后接入丁醇菌,共发酵48 h,总溶剂质量浓度可达到10.33 g/L,其中丁醇为7.8 g/L。该研究为利用农业废弃物进行新能源的开发提供了实验依据。     

Sago starch saccharification and simultaneous ethanol fermentation by amyloglucosidase and Zymomonas mobilis

Simultaneous saccharification and ethanol fermentation (SSF) of sago starch was studied using amyloglucosidase (AMG) and Zymomonas mobilis. The optimal concentration of AMG and operating temperature for the SSF process were found to be 0.5% (v/w) and 35°C, respectively. Under these conditions with 150 g dm^?3 sago starch as a substrate, the final ethanol concentration obtained was 69.2 g dm^?3 and ethanol yield, Y_P/S, 0.50 g g^?1 (97% of theoretical yield). Sago starch in the concentration range of 100–200 g dm^?3 was efficiently converted into ethanol. When compared to a two-step process involving separate saccharification and fermentation stages, the SSF reduced the total process time by half.     

表面活性剂对麦草同步糖化发酵转化乙醇的影响

研究了5种非离子型表面活性剂(BSA, Tween-20, Tween-80, PEG-4000, PEG-6000)促进麦草同步糖化发酵的效果. 结果表明,5种表面活性剂均能促进麦草同步糖化发酵,以Tween-20效果最为显著. 反应体系中添加Tween-20可降低酶用量而保持乙醇浓度基本相同. 在pH 5.0、温度37℃、底物浓度50 g/L及Celluclast 1.5 l用量25 FPU/g、Novozym 188用量15 IU/g的反应体系中,添加0.03 g/g Tween-20,反应72 h,乙醇浓度达到18.7 g/L,比未添加表面活性剂的体系提高了14.0%,反应时间缩短了12 h.     

Effect of simultaneous saccharification and fermentation conditions of native triticale starch on the dynamics and efficiency of process and composition of the distillates obtained

BACKGROUND: Among ethanol production technologies, attention should be focused towards simultaneous saccharification and fermentation of native starch with enzymes capable of its degradation without prior gelatinization. Selection of process conditions makes it possible to achieve high efficiency of the process and to reduce the costs of the production of ethanol. RESULTS: This study determined the effect of hydrolysis conditions of native triticale starch based on the results of their fermentation and concentration of by‐products in the distillates obtained. The pre‐activation of starch with acid α‐amylase is not necessary for the proper conduct and efficiency of saccharification and fermentation of native triticale starch. Beneficial impact on the synthesis of ethanol was afforded by the treatment of mashes with protease preparation (EC 3.4.21.62) (Bacillus licheniformis). Raising the pH of mashes from 3.6 to 4.8 did not improve the ethanol yield. Process conditions had a diversified impact on concentration of by‐products in the raw spirits obtained. CONCLUSION: Under the optimal conditions found in these experiments 63.01 ± 0.33–63.56 ± 0.33 L of absolute ethanol was obtained from 100 kg of starch. Simultaneous saccharification and fermentation of the native starch raw materials, especially without pre‐activation of starch, can simplify the process and improve the economic index in the alcohol‐distilling industry. © 2012 Society of Chemical Industry     

β-葡萄糖苷酶高温同步糖化发酵产乙醇应用研究

利用Trichoderma sp.W2所产的嗜温耐乙醇β-葡萄糖苷酶及耐高温酵母Kluyveromyces marxianus NCYC 587,以气爆秸秆为原料进行高温同步糖化发酵。研究结果表明:在42℃条件下,接种体积分数10%,底物质量分数15%,发酵pH值为4.8,β-葡萄糖苷酶添加量为30 U/g底物条件下发酵效果最好。NCYC 587能迅速利用预水解产生的葡萄糖发酵并积累乙醇,同时能利用部分木糖,但在发酵后期,葡萄糖利用完全后会代谢利用一定量的乙醇,致使发酵过程中乙醇质量浓度始终维持在一个相对较低的水平。乙醇最高质量浓度达到20.56 g/L,乙醇产率达80.64%。添加嗜温耐乙醇β-葡萄糖苷酶于高温同步糖化发酵能有效解决纤维素酶解发酵过程终端产物抑制的难题。     

Protease production by Aspergillus oryzae in solid‐state fermentation using agroindustrial substrates

BACKGROUND: An inexpensive and readily available agroindustrial substrate such as rice bran can be used to produce cheap commercial enzymes by solid‐state fermentation. This work investigates the production of food‐grade proteases by solid‐state fermentation using readily available Thai rice bran. RESULTS: A local strain of Aspergillus oryzae (Ozykat‐1) was used to produce proteases. Rice bran used alone proved to have poor substrate morphology (insufficient porosity) for satisfactory solid‐state fermentation. A certain amount of wheat bran was necessary to improve the morphology of the substrate. The following variables affected protease production: substrate composition, initial moisture content and initial pH. A high protease activity (∼1200 U g⁻¹ dry solids) was obtained on a substrate that had a wheat bran to rice bran ratio of 0.33 by dry weight, a moisture content of 50%, initial pH of 7.5, and incubation temperature of 30 °C. CONCLUSION: Nutritionally, rice bran used alone was as good a substrate as mixed bran for producing protease, but rice bran had poor morphological characteristics for consistent fermentation. A substrate that had a wheat bran to rice bran ratio of 0.33 by dry weight was best for producing protease. Copyright © 2008 Society of Chemical Industry     

玉米芯HNO_3/HCl预处理及同步糖化发酵制乙醇

采用正交实验对玉米芯在2%HNO3/HCl中的水解条件进行优化,得出最适宜的预处理条件为：反应温度120℃,反应时间30 min,固含量15%。将经过预处理的玉米芯作为同步糖化发酵的底物,采用单因素实验考查影响发酵的因素,结果表明：在底物浓度为150 g/L、37℃、pH值为5.0、纤维素酶用量为30 FPU/g底物、酵母接种量10%、发酵周期72 h时,乙醇的产率可达到76.8%,此时乙醇溶液的浓度为41.4 g/L。     

一种竹腐朽菌胞外木聚糖酶的分离和特性研究

从腐朽的竹子上分离得到一株产木聚糖酶侧耳真菌Pleurotus sp.GH196,研究了其液体振荡培养的产酶条件。适宜碳源是1%稻草粉与1%麸皮组成的复合碳源,氮源是0.2%NH4NO3。经过硫酸铵分级沉淀、DEAE-Sephadex A-25离子交换层析、Sephadex G-100凝胶过滤三步纯化得到木聚糖酶的一个主要酶活组分A。该木聚糖酶在40～50℃、pH 4.0～5.5可以保持较好的稳定性,酶活最适反应条件是温度55℃、pH 4.5。     

Simultaneous saccharification and fermentation of pretreated Antigonum leptopus (Linn) leaves to ethanol

Simultaneous saccharification and fermentation (SSF) of alkaline hydrogen peroxide pretreated Antigonum leptopus (Linn) leaves to ethanol was optimized using cellulase from Trichoderma reesei QM‐9414 (Celluclast® from Novo) and Saccharomyces cerevisiae NRRL‐Y‐132 cells. Contrary to the saccharification optima (2.5% w/v substrate concentration, 50 °C, 4.5 pH, 40 FPU cellulase g⁻¹ substrate and 24 h reaction time), the SSF optima was found to be somewhat different (10% w/v substrate, 40 °C, 100 FPU cellulase g⁻¹ substrate and 72 h). Better ethanol yields were obtained with SSF compared with the traditional saccharification and subsequent fermentation (S&F) and when the cellulase was supplemented with β‐glucosidase. © 1999 Society of Chemical Industry     

Ethanol-Herstellung mit Bakterien

Ethanol production with bacteria . Strains of Saccharomyces cerevisiae have mostly been used for the production of ethanol from sugar by yeasts. Recently it was shown that the bacterium Zymomonas mobilis has some advantages compared to yeast for the production of industrial alcohol. Compared to traditional yeast fermentation, ethanol yield is about 5% higher than with yeast, since less sugar is incorporated into cell material by this bacterium. Like yeast, Zymomonas mobilis has remarkably high ethanol tolerance which enables the bacterium to produce ethanol concentrations of more than 13 vol.-% from sugar solutions of appropriate concentration. Investigations of the spectrum of lipids present have shown that this bacterium contains large quantities of hopanoids which are presumably of significance for the stabilization of cell membranes in the presence of ethanol. Since the cost of the sugar greatly influences the profitability fraction formed in the production of glucose syrup from wheat flour was investigated. It was shown that after enzymatic saccharification of this waste starch the glucose was efficiently fermented to ethanol by Zymomonas mobilis. It is planned to broaden the substrate spectrum of Zymomonas mobilis by gene cloning techniques so that in future pentoses, e. g. xylose or arabinose, can also be fermented to ethanol by this organism.     

FED-BATCH SIMULTANEOUS SACCHARIFICATION AND FERMENTATION OF MICROWAVE/ACID/ALKALI/H2O2 PRETREATED RICE STRAW FOR PRODUCTION OF ETHANOL

The batch simultaneous saccharification and fermentation (SSF) of microwave/acid/alkali/H₂O₂ pretreated rice straw to ethanol was optimized using cellulase from Trichoderma reesei and Saccharomyces cerevisiae YC-097 cells prior to the fed-batch SSF studies. The batch SSF optima were 10% w/v substrate, 40°C, 15 mg cellulase/g substrate, initial pH 5.3, and 72 hours. Under the optimum conditions the ethanol concentration and its yield were 29.1 g/L and 61.3% respectively. Based on the optimal batch SSF, the fed-batch SSF was investigated and its operation parameters were optimized. Under its optimal conditions the ethanol concentration reached 57.3 g/L, while its productivity and yield were only slightly less than those in the batch SSF. This suggests that fed-batch SSF is a potential operation mode for effective ethanol production from microwave/acid/alkali/H₂O₂ pretreated rice straw.     

一株青霉发酵产生木素过氧化物酶的工艺条件

研究了一株青霉菌P6 (Penicillium sp. P6)液体发酵产生木素过氧化物酶的工艺条件,考察了青霉菌P6在天然培养基稻米糠、玉米糠、麦糠和合成培养基GMY中的产酶情况,结果表明,麦糠是较理想的底物. 通过单因素方法研究了添加苯甲醇和MnSO4对酶活的影响;采用正交实验对MnSO4添加量、麦糠含量和培养基pH进行了研究,在实验范围内最佳酶活达到了2.69 U/mL. 进一步通过单双因素回归实验研究了麦糠和MnSO4的最佳含量,得到了最佳培养条件为孢子接种量1.1×106 mL-1,培养时间8 d,500 mL三角瓶装液量150 mL. 最佳培养基组成为麦糠50 g/L,初始pH 4.8, MnSO4 5.66 mmol/L.     

糠醛渣直接同步糖化发酵生产乙醇过程比较研究

以糠醛渣为原料,直接同步糖化发酵(SSF)生产乙醇,并与水洗糠醛渣生产乙醇进行对比。通过考察不同条件来优化同步糖化发酵生产工艺条件,并分析表征了SSF过程中乙醇浓度和副产物浓度变化。优化条件为:糠醛渣底物质量分数10%,纤维素酶用量12%,无患子皂素质量浓度0.5g/L,酵母接种量7g/L,同步糖化发酵乙醇得率达到其理论得率的93.1%。与水洗糠醛渣相比,糠醛渣直接SSF过程可将原料吸附的5.50%葡萄糖部分转化为乙醇。水洗糠醛渣SSF生产乙醇所产生的副产物要远低于糠醛渣直接生产所产生的副产物,添加无患子皂素可有效抑制糠醛渣同步糖化发酵过程中副产物的产生。     

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 fermentation (SSF), the final ethanol concentration reached 15.5% (v/v), and the total sugar conversion and ethanol yields were 96.5% and 87.8%, respectively.