诱变管囊酵母发酵木糖产乙醇的研究

通过Co⁶⁰诱变使管囊酵母利用木糖发生突变。经在纯木糖培养基上的筛选,分离得到有较高木糖利用效率和乙醇发酵效率的诱变菌株800-3,考察了发酵条件对其产乙醇的影响。结果证明,溶氧量和培养基组分对于乙醇的产率有重要影响,在转速100 r/min,100 mL三角烧瓶中装液20 mL,酵母浸膏浓度1 g/L条件下,发酵液中的乙醇质量浓度只有5.86 g/L,而木糖醇质量浓度可以达到12.95 g/L,乙醇产率与前人的研究结果相比还有较大差距。     

Co60诱变管囊酵母发酵木糖产乙醇的研究

通过Co⁶⁰诱变使管囊酵母利用木糖发生突变。经在纯木糖培养基上的筛选,分离得到有较高木糖利用效率和乙醇发酵效率的诱变菌株800-3,考察了发酵条件对其产乙醇的影响。结果证明,溶氧量和培养基组分对于乙醇的产率有重要影响,在转速100 r/min,100 mL三角烧瓶中装液20 mL,酵母浸膏浓度1 g/L条件下,发酵液中的乙醇质量浓度只有5.86 g/L,而木糖醇质量浓度可以达到12.95 g/L,乙醇产率与前人的研究结果相比还有较大差距。     

四株酵母乙醇发酵的初步研究

比较了休哈塔假丝酵母NLP21、树干毕赤酵母NLP22、NLP23和NLP31,在30 g/L的木糖和混合糖(葡萄糖15 g/L+木糖15 g/L)发酵培养基上以及在培养基中氮源浓度降低到原来1/2和1/10时的发酵性能。结果表明,在30 g/L木糖发酵培养基上,NLP23和NLP31产乙醇质量浓度最高,分别为(11.14±0.13)和(11.15±0.08) g/L。在15 g/L葡萄糖+15 g/L木糖混合糖发酵培养基上,NLP31产乙醇质量浓度最高,为(10.91±0.12) g/L。当发酵培养基中氮源浓度降低到原来的1/2时,NLP23和NLP31产乙醇能力相当,但后者产木糖醇的量增大;当氮源质量浓度降低到原来的1/10时,NLP23和NLP31产乙醇能力随着发酵轮数的增加,逐渐下降,氮源浓度低,降低了乙醇的产量。     

氮源影响酵母耐受超高浓度乙醇发酵胁迫条件

为考察蛋白胨和酵母浸出膏对酵母耐受超高浓度乙醇发酵胁迫条件的影响,以300g/L起始浓度葡萄糖开展实验。结果表明,与对照组(3g/L蛋白胨+5g/L酵母浸出膏作为氮源)相比,单独提高发酵培养基蛋白胨至6g/L或酵母浸出膏至12g/L,均可明显促进菌体生长和葡萄糖利用,终点乙醇体积分数由对照组的13.1%分别提高至14.4%和14.7%。研究表明,在发酵过程中,生长于提高蛋白胨浓度或酵母浸出膏浓度培养基的菌体,其质膜ATP酶活力和胞内海藻糖积累量明显高于对照组,而且发酵参数(如菌体生长、葡萄糖利用和终点乙醇体积分数)的提高与酶活力和海藻糖含量的增加密切相关,提示质膜ATP酶和胞内海藻糖在酵母耐受超高浓度乙醇发酵胁迫条件中的作用。     

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。     

驯化树干毕赤酵母发酵产乙醇的研究

以玉米秸秆蒸汽爆破液为底物培养基,通过逐步提浓的方式对树干毕赤酵母菌株（Pichiastipitis）NLP23进行耐抑制物驯化,驯化后的菌株对汽爆液中甲酸和乙酸等抑制物的耐受能力可分别达到2．70g／L和3．54g／L,较出发菌株分别提高253．40％和277．80％。在含有57．34g/L木糖和13．84g／L葡萄糖的汽爆液中发酵42h,糖利用率和乙醇得率可达到97．89％和65．83％,乙醇质量浓度为21．56g/L,同时生成4．16g/l木糖醇。玉米秸秆蒸汽爆破液中含有多种抑制酵母生长和发酵的有毒物质,主要是甲酸、乙酸、乙酰丙酸、糠醛和羟甲基糠醛,其中甲酸和乙酸含量较高,是影响树干毕赤酵母NLP23发酵汽爆液的主要抑制物。     

虎奶菇菌丝体胞外多糖深层发酵培养基的优化

研究了营养性因子对虎奶菇菌丝体深层发酵的影响,结果表明蔗糖、马铃薯、蛋白胨和酵母膏有利于胞外多糖的形成。进一步的正交优化实验确定了虎奶菇多糖深层发酵的最佳培养基组成(g/L)为∶蔗糖2 g/100 mL,马铃薯25 g/100 mL,蛋白胨0.2 g/100 mL,酵母膏0.2 g/100 mL。     

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.     

拟薄水铝石-海藻酸铝固定化酵母生产乙醇

在原位合成拟薄水铝石中加入酵母和海藻酸钠,搅拌并冷冻后制备固定化酵母,以甘蔗废糖蜜生产乙醇。通过复合材料固定化酵母增殖机理发现,固定化酵母数达4.1×109个/mL,批式发酵中14h消耗了90.5%的总糖;40d连续流动中,稀释率为0.100h-1时,最大载体乙醇产率为52.0g/(L.h)。SEM表征表明,该固定化酵母细胞密度高,孔道结构丰富,利于细胞的繁殖生长和物质传送。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质量浓度均超过传统工艺。     

LSM蛋白增强木糖发酵重组酵母抗逆性能的研究

木质纤维素原料预处理过程中产生的弱酸、呋喃醛类和酚类化合物等对酿酒酵母的乙醇发酵有抑制作用,提高基因重组酵母对抑制物的耐受性,是利用植物秸秆水解液生产燃料乙醇的关键技术之一。研究从前期构建的戊糖、己糖共发酵重组酿酒酵母Saccharomyces cerevisiae ZU-E8基因组DNA中克隆出RNA结合蛋白LSM6,将其连入含有PADH启动子的质粒构成表达载体pR-LSM,进而转入ZU-E8宿主细胞中。通过高浓度醋酸根平板筛选,得到高抗逆性木糖发酵重组酵母ZU-910。在醋酸浓度为2 g·L-1的木糖培养基中发酵96 h后,ZU-910的木糖利用率和乙醇浓度为90.2%和26.9 g·L-1,分别是出发菌株ZU-E8的8.5和10倍,并且ZU-910对糠醛和硫酸根的耐受能力也较ZU-E8大大增强。在玉米秸秆酶解液发酵中,ZU-910的木糖利用率和乙醇产量在ZU-E8基础上增加了10.5%和7.7%.证明LSM6蛋白确实能够增强木糖发酵重组酵母的抗逆能力,提高其发酵性能。该研究成果在木质纤维素替代粮食生产乙醇的产业化进程中具有良好的应用前景。     

Impact of Phosphate,Potassium, Yeast Extract,and Trace Metals on Chitosan and Metabolite Production by Mucor indicus

In this study the effects of phosphate, potassium, yeast extract, and trace metals on the growth of Mucor indicus and chitosan, chitin, and metabolite production by the fungus were investigated. Maximum yield of chitosan (0.32 g/g cell wall) was obtained in a phosphate-free medium. Reversely, cell growth and ethanol formation by the fungus were positively affected in the presence of phosphate. In a phosphate-free medium, the highest chitosan content (0.42 g/g cell wall) and cell growth (0.66 g/g sugar) were obtained at 2.5 g/L of KOH. Potassium concentration had no significant effect on ethanol and glycerol yields. The presence of trace metals significantly increased the chitosan yield at an optimal phosphate and potassium concentration (0.50 g/g cell wall). By contrast, production of ethanol by the fungus was negatively affected (0.33 g/g sugars). A remarkable increase in chitin and decrease in chitosan were observed in the absence of yeast extract and concentrations lower than 2 g/L. The maximum chitosan yield of 51% cell wall was obtained at 5 g/L of yeast extract when the medium contained no phosphate, 2.5 g/L KOH, and 1 mL/L trace metal solution.     

The bioconversion of ethanol to biosurfactants and dye by a novel coproduction technique

Rhamnolipids, multifunctional glycolipid biosurfactants, and pyocyanine, a phenazine dye, were coproduced byPseudomonas BOP100 from ethanol as the sole carbon source. Bacterial growth was dependent on the ethanol concentration in the medium. Pyocyanine was produced only during the exponential phase, while rhamnolipids production continued during the stationary phase, indicating two different ways of production for each of the products. Maximum coproduction capacity was observed at a concentration of 3% ethanol; yield of rhamnolipids was 3 g/L, and of pyocyanine 0.2 g/L. The products were characterized to confirm their chemical structures.     

产乙醇基因工程集胞藻的盐胁迫响应

采用含不同浓度NaCl的培养基培养产乙醇基因工程集胞藻,研究盐胁迫对其细胞生长和乙醇产量的影响,并探讨其响应机制. 结果表明,随培养液中NaCl浓度提高,藻生长速率降低;盐胁迫损伤细胞光反应中心II的活性,抑制细胞的光合作用;盐浓度大于10 g/L时,呼吸作用略有提高. 随盐浓度提高,集胞藻的内源性代谢产物乙醇产量显著提高,在20 g/L NaCl中培养,乙醇产量较对照提高91.8%. 在盐胁迫条件下,基因工程集胞藻通过调节光合作用和呼吸作用效率、提高乙醇脱氢酶的活性而提高内源性的代谢以应对胁迫,同时提高乙醇产量.     

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。     

海洋微生物溶菌酶的发酵优化与中试生产

以海洋细菌S-12-86为试验菌株,采用摇瓶发酵优化的方式,研究培养基组分(碳源、氮源、碳源与氮源的比例、金属离子)与发酵条件(培养温度、接种体积分数、装液体积分数、起始pH值、产酶周期)对海洋微生物溶菌酶产量的影响,并进行中试放大试验。结果表明:该菌产酶最佳培养基组分为:葡萄糖10 g/L,蛋白胨5 g/L,MgSO45 g/L,CaCl22 g/L;最适发酵培养温度为30℃,接种体积分数为4.0%,装液体积分数为10.0%,起始pH值为8.0,发酵周期24 h。海洋细菌S-12-86发酵优化后的产酶量(25636.8 U/mL)较优化前的产酶量(14454.4 U/mL)提高了75.4%。海洋微生物溶菌酶中试发酵的产酶量达26697.87 U/mL。说明摇瓶发酵优化条件可以应用于海洋微生物溶菌酶中试生产上。     

Ethanol production from sweet sorghum residual

In this work, the ethanol production from sweet sorghum residue was studied. Sweet sorghum residue was hydrolyzed with phosphoric acid under mild conditions. The liquid hydrolysate was fermented by Pachysolen tannophilus, and the hydrolysis residue was fermented by the simultaneous saccharification and fermentation (SSF) using Saccharomyces cerevisiae with cellulase (60 FPU/g dry materials). Orthogonal experiments were carried out to investigate the effects of main reaction condition factors, such as temperature, acid concentration, time and dry-matter content, on the reducing sugar yield. The results show that the optimal reaction conditions should be 120°C, 80 g/L, 80 min and 10%, respectively. Under these conditions, 0.3024 g reducing sugar/g dry material was obtained. The liquid hydrolysate was then fermented by P.tannophilus with the highest ethanol concentration of 14.5 g/L. At a water-insoluble solid concentration of 5%, 5.4 g/L ethanol was obtained after 12 h of SSF. The total ethanol yield was 0.147 g/g dry material, which would be beneficial for the application of ethanol production from sweet sorghum residue. __________ Translated from Journal of Beijing University of Chemical Technology, 2007, 34(6): 637-639, 652 [译自: 北京化工大学学报]     

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)。     

Extraction of oil from ground corn using ethanol

Corn oil was extracted from whole ground corn using ethanol as the solvent. The yield of oil was measured as a function of temperature, time of extraction, solvent-to-solids ratio, and ethanol concentration. Optimal conditions were a solvent-to-solids ratio of 4 mL/g corn, an ethanol concentration of 100%, 30 min of extraction time, and a temperature of 50°C. Under these conditions, a single batch extraction yielded ≈3.3 g oil/100 g corn, equivalent to 70% extraction efficiency. A three-stage extraction, where the same corn was exposed to fresh ethanol, resulted in a yield of ≈4.5 g/100 g corn (2.5 lb/bu of corn), equivalent to 93% recovery of the oil in corn. When anhydrous ethanol was used to repeatedly extract fresh corn, moisture was absorbed linearly by ethanol from the corn in successive stages, which, in turn, decreased oil yield and increased nonoil components in the extract.