冰糖橙皮渣发酵产燃料乙醇的工艺优化

采用纤维素酶、果胶酶和β-葡萄糖苷酶对冰糖橙皮渣进行水解,所得还原糖液接种异常毕赤酵母进行发酵,考察了酵母接种量、发酵时间、pH和发酵温度等单因素对乙醇得率的影响。单因素结果表明:接种量为12%、发酵时间72 h、pH 4.5、发酵温度33℃时乙醇得率最高。在此基础上设计L9(34)正交实验。结果表明,最佳工艺条件为pH 4.5,接种量12%,发酵时间72 h,发酵温度30℃。在此条件下乙醇产率为0.2451 g/g,显著高于单因素实验(0.2263 g/g)和正交实验结果(0.2329 g/g)。     

自絮凝颗粒酵母发酵菊芋汁生产乙醇

分别采用分批和连续发酵方式,对自絮凝颗粒酵母Saccharomyces cerevisiae flo发酵菊芋汁生产乙醇的条件进行了优化. 与先酶解菊芋汁后再用自絮凝酵母发酵的分步糖化发酵相比,分批发酵过程中同时加入菊粉酶和自絮凝酵母的同步糖化发酵乙醇得率高,发酵时间短. 当菊芋汁总糖浓度分别为105和179 g/L时,同步糖化发酵的最高乙醇浓度达50和82.5 g/L,比分步糖化发酵高6.4%和13.8%. 在连续发酵过程中应用同步糖化发酵法,当稀释率为0.02 h-1时,乙醇浓度约为90 g/L时达到稳定状态,乙醇得率达到理论值的90%,生产强度达2.12 g/(L×h).     

改性无纺布-壳聚糖固定化酵母生产燃料乙醇

采用含酵母的壳聚糖溶液经木质素磺酸钠交联的方法包埋固定化在环氧氯丙烷改性的聚丙烯无纺布上.以甘蔗废糖蜜为原料,研究固定化酵母的发酵及增殖机理发现,酵母包埋量达3.7×109/mL,在批式发酵中,初始糖质量浓度167g/L、填充率12%、pH 4.0、温度34℃时,发酵成熟醪酒精质量浓度达78.2 g/L、残糖质量浓度12.8 g/L、发酵周期缩短至10.5 h.连续流动发酵实验中,材料使用40 d没有破损,乙醇发酵过程彻底,速率快,残糖水平低,原料利用率和发酵醪乙醇浓度均超过传统工艺.     

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。     

菊芋秸秆的稀酸水解及乙醇发酵

菊芋作为一种非粮作物,块茎和秸秆均可以被微生物发酵生成乙醇。采用稀酸法对菊芋秸秆进行预处理,通过单因素实验,考察了预处理温度、预处理时间、稀酸浓度、料液比4个因素,得到的优化结果:料液比为1∶8,酸解温度为121℃,酸质量分数为1.5%,酸解时间为1 h。此条件下水解菊芋秸秆,还原糖得率高达53.7%;预处理后的水解液在添加纤维素酶和木聚糖酶后,考察Kluyveromyces marxianus 1727的乙醇发酵能力,其同步糖化发酵与分步糖化发酵乙醇产量分别为25.91 g/L和25.63 g/L,生产效率分别是0.54 g/L/h和0.26 g/L/h。结果表明,稀酸水解的菊芋秸秆可用作底物生产燃料乙醇。     

玉米芯稀酸预处理和分步糖化与发酵工艺生产燃料乙醇的中试研究

利用正交试验在中试水平考察了玉米芯的稀硫酸预处理和分步糖化与水解生产乙醇的工艺。结果:最佳预处理工艺为稀硫酸浓度1.1%,温度120℃,固液比1∶8,时间3 h;酶解糖化最佳工艺为:起始底物浓度180 g/L,滤纸酶活:纤维二糖酶活=20 IU/g底物:7 IU/g底物,pH=5.0,48 h;利用运动发酵单胞菌发酵酶解液,35℃,48 h,发酵液中乙醇浓度最高67.8 g/L。     

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。     

糠醛渣纤维乙醇同步糖化发酵过程研究

以过碱化处理的糠醛渣为原料,采用正交试验法进行同步糖化发酵(SSF)转化乙醇工艺条件及过程研究.通过考察反应温度、pH、纤维素酶用量和表面活性剂浓度来优化同步糖化发酵转化工艺条件.在正交优化条件基础上,进行了5 L发酵罐试验,并同步分析表征了发酵过程中还原糖浓度、乙醇浓度、酵母细胞数、纤维素含量及其结构变化.同步糖化发酵转化糠醛渣生成乙醇的优化条件为:反应温度38℃,pH 4.2,纤维素酶用量20 FPU/(g纤维素),吐温-20质量分数0.15%,酵母接种量10%.发酵罐中同步糖化发酵糠醛渣生成乙醇的转化率达到72.33%,过程分析表明反应时间为27 h时,糠醛渣糖化发酵产乙醇的转化率达到最高,比其他纤维原料的反应转化时间大大缩短.同步糖化发酵过程中,糠醛渣纤维素含量逐步降低,纤维索表观结晶度呈下降趋势,纤维素微晶尺寸减小.     

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%。     

玉米秸秆发酵生产乙醇的研究

以1.5%硫酸120℃处理60min、又被1%氢氧化钠80℃处理60min的玉米秸秆为底物。正交优化了利用其糖化液发酵产乙醇的条件,在温度34℃、酵母接种量4%(体积分数)、玉米浆加量0.4%(体积分数)的发酵条件下反应48h产生乙醇40.2g/L,纤维素乙醇转化率为86%。     

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.     

短乳杆菌CGMCC1306pH和温度两阶段控制结合底物补加方式生产γ-氨基丁酸(英文)

Methods to optimize the production of gamma-aminobutyric acid （GABA） by Lactobacillus brevis CGMCC 1306 were investigated. Results indicated that cell growth was maximal at pH 5.0, while pH 4.5 was pref-erable to GABA formation. The optimal temperature for cell growth （35 °C） was lower than that for GABA forma-tion （40 °C）. In a two-stage pH and temperature control fermentation, cultures were maintained at pH 5.0 and 35 °C for 32 h, then adjusted to pH 4.5 and 40 °C, GABA production increased remarkably and reached 474.79 mmol·L-1 at 72 h, while it was 398.63 mmol·L-1 with one stage pH and temperature control process, in which cultivation con-ditions were constantly controlled at pH 5.0 and 35 °C. In order to avoid the inhibition of cell growth at higher L-monosodium glutamate （L-MSG） concentrations, the two-stage control fermentation with substrate feeding strat-egy was applied to GABA production, with 106.87 mmol （20 g） L-MSG supplemented into the shaking-flask at 32 h and 56 h post-inoculation separately. The GABA concentration reached 526.33 mmol·L-1 at 72 h with the fer-mentation volume increased by 38%. These results will provide primary data to realize large-scale production of GABA by L. brevis CGMCC 1306.     

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 °C up to 30 h.The operating temperature increased rapidly to 31.9 °C,and then decreased slowly to 18 °C at 65 h.Thereafter,the temperature was maintained at18 °C 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.     

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。     

赤藓糖醇发酵工艺优化

以解脂假丝酵母CGMCC2．2088为出发菌株,经过菌种选育得生产菌株为研究对象,对该菌株的发酵培养基和培养条件进行优化,其发酵最适温度为32％,对数生产期溶氧控制在30％,发酵期溶氧控制在20％,发酵结果糖醇含量达到181．6g／L。     

Continuous ethanol production by the synchronous saccharification and fermentation using food wastes

The synchronous saccharification and fermentation (SSF) by continuous fill and draw method was investigated in order to develop a continuous ethanol fermentation process using the food wastes (FW) available among Korea’s organic wastes. The activity of the hydrolytic enzymes was maintained constantly in the continuous culture by their intermittent addition together with medium exchange. The concentrations of reducing sugar in the culture were maintained at a steady state by regulating supplemented enzyme concentration and exchange rate of medium, reflecting on the consumption rate of reducing sugar caused by the fermentation. When the temperature of the SSF was maintained at the fixation of 35 °C, which enabled us to perform both enzymatic hydrolysis and enzyme fermentation simultaneously, the rate of reducing sugar consumption was 3.61 g/L-hr. For the enzymatic saccharification of FW, when 0.01 BGU as Viscozyme/g-FW and 0.05 AGU as Spirizyme Plus/g-FW were used, the production rate of reducing sugar was 3.93 g/L-hr, indicating a little higher rate of production than that of consumption. A decompression device with ethanol condensing ability was used to continuously pull out ethanol from the culture broth at −600 mmHg, where the ethanol evaporation ability would be maximized and the water evaporation minimized during the process. As a result of the continuous SSF performance, the reducing sugar concentration was maintained at around 30 g/L. The amylase activity was maintained at 8.93±2.17 U/mL. During a 352 hour culture, the whole ethanol productivity was 2.24 g/L-hr, indicating a considerable productivity compared with the other result reported in the continuous SSF.     

木薯干原料同步糖化发酵生产乙醇

提出了用木薯干为原料,同步糖化发酵(SSF)开发燃料乙醇的新工艺. 对各个影响条件进行了研究,获得了最佳的工艺条件：原料粉碎粒度0.45 mm,加水比2.8, 100℃下蒸煮30 min,a-淀粉酶、糖化酶的添加量分别为10, 180 U/g, 30℃下发酵48 h. 并与普通的先糖化后发酵(SHF)生产模式进行了对比,认为SSF具有工艺简单、能耗低、发酵迅速、醪液酒精度高等众多优点,值得工业推广.     

Comparison of bioethanol production of simultaneous saccharification & fermentation and separation hydrolysis & fermentation from cellulose-rich barley straw

Cellulose rich barley straw, which has a glucan content of 62.5%, followed by dilute acid pretreatment, was converted to bioethanol by simultaneous saccharification and fermentation (SSF). The optimum fractionation conditions for barley straw were an acid concentration of 1% (w/v), a reaction temperature of 158 °C and a reaction time of 15 min. The maximum saccharification of glucan in the fractionated barley straw was 70.8% in 72 h at 60 FPU/gglucan, while the maximum digestibility of the untreated straw was only 18.9%. With 6% content WIS (water insoluble solid) for the fractionated barley straw, 70.5 and 83.2% of the saccharification yield were in SHF and SSF (representing with glucose equivalent), respectively, and a final ethanol concentration of 18.46 g/L was obtained under the optimized SSF conditions: 34 °C with 15 FPU/g-glucan enzyme loading and 1 g dry yeast cells/L. The results demonstrate that the SSF process is more effective than SHF for bioethanol production by around 18%.     

木薯酒精渣的预处理及补料同步糖化发酵制取乙醇

木薯酒精渣的处置是制约木薯燃料乙醇大规模产业化的问题之一。本文立足于探索木薯酒精渣利用途径,分析了木薯酒精渣的主要成分,对比了氨水、氢氧化钠、氨水组合稀硫酸3种预处理方式对于木薯酒精渣纤维素和木素含量及纤维素酶水解效率的影响,分析了处理前后木薯酒精渣的表面结构及纤维素结晶度,并以氨水处理后的木薯酒精渣为底物,进行了同步糖化发酵。结果表明,3种预处理方法中组合预处理能更好地增加纤维素含量和提高纤维素酶水解效率,与未处理原料相比,组合预处理后纤维素含量增加了111.26%,木素下降了35.05%,酶水解72h纤维素转化率从42.10%增加到61.71%。氨水预处理后,原料的木素含量降低,处理后木薯酒精渣的表面变得更加粗糙,纤维素结晶度有所增加,以氨水处理后的木薯酒精渣为底物进行分批补料同步糖化发酵,当初始底物浓度为100.0g/L,分别在20h、40h、60h进行补料至最终底物浓度为400.0g/L时,发酵120h乙醇浓度达到51.0g/L。