热带假丝酵母用未脱毒汽爆玉米秸秆产乙醇研究

为阐明专利菌种Candida tropicalis Y1利用玉米秸秆产乙醇的能力,以未脱毒汽爆玉米秸秆为原料进行分步糖化发酵(SHF)及同步糖化发酵(SSF)产乙醇。研究结果表明,底物浓度为25%(w/v)、纤维素酶15FPU/(g底物)、纤维二糖酶Novozyme 188 20IU/(g底物)、接种量5%(v/v)及不需添加任何外源营养物质,该菌在SHF过程中的乙醇浓度为38.75g/L乙醇,为理论产率的77.9%,在SSF过程中的乙醇浓度为40.53g/L;同时,SSF与SHF相比,SSF可得到更多的木糖醇,且毒性物质乙酸的浓度维持在较低水平。说明该专利菌株不但有较强的耐发酵抑制剂的能力,而且有较好的代谢葡萄糖和木糖分别产乙醇和木糖醇的能力。     

玉米秸秆同步糖化发酵产乙醇优化实验研究

以耐高温酿酒酵母为对象,研究高温酿酒酵母利用玉米秸秆为原料同步糖化产氢乙醇的影响因素,采用Plackett-Burman(PB)法对影响乙醇产率的5个因素进行筛选,采用CCD模型及响应面分析对影响因素进行优化设计,确定高温酿酒酵母利用玉米秸秆为原料同步糖化产氢乙醇的最佳工艺条件。研究结果表明:高温酿酒酵母利用玉米秸秆酶解液同步糖化产乙醇过程中接种量、温度、酶浓度和发酵时间4个因素对乙醇产量的影响最为明显,温度和发酵时间的交互作用最为显著。利用优化设计得到的最佳产乙醇工艺为:接种量7.4%、温度34.2℃、初始p H值5.0、酶浓度49.36 U/g。在此条件下,发酵105.12 h后乙醇产率可达59.88%,实验结果与响应面拟合方程的预测值(60.85%)吻合良好。     

未脱毒汽爆玉米秸秆高底物浓度的同步糖化和乙醇发酵

为取消蒸汽爆破预处理玉米秸秆水洗脱毒步骤和提高乙醇发酵的乙醇浓度,利用专利菌株酿酒酵母Y5,对蒸汽爆破预处理玉米秸秆不经脱毒处理,直接进行同步糖化和发酵(SSF)。蒸汽爆破玉米秸秆的浓度30%,同步糖化和发酵的时间96 h,100 m L、3000 m L反应器和5L发酵罐的乙醇浓度分别达到50.0、47.8、47.5 g/L。研究结果表明,菌株Y5在纤维素乙醇生产中对简化生产工艺、降低设备投资、减少水消耗、降低生产成本具有重要的应用前景。     

汽爆玉米秸秆产乙醇的补料同步糖化发酵优化

为提高反应系统中的底物浓度,减少酶用量,以蒸汽爆破预处理的玉米秸秆及高性能的酵母菌株Y5进行补料同步糖化发酵研究。通过同步糖化发酵策略的优化,经两次补料使反应体系底物浓度提高至25.7%,同步糖化发酵72h,即可获得41.7g/L的乙醇浓度,综合转化率64%。同时,纤维素酶及β-葡萄糖苷酶用量分别可降至7FPU/(g纤维素)及7IU/(g纤维素)。     

两株高效代谢木质纤维素稀酸水解物产乙醇的酵母特性及耐毒研究

对实验室筛选出的两株高效代谢木质纤维素稀酸水解液产乙醇的酵母菌Y1(Candida tropicalis)和Y4(Issatchenkiaorientalis)的乙醇发酵特性及耐毒能力进行研究。以未经任何脱毒处理的木质纤维素稀酸水解液为发酵底物进行乙醇发酵(原位脱毒乙醇发酵)。结果表明:Y1和Y4均能在24h内将水解液中所有的葡萄糖消耗完,乙醇产率分别为0.49g/g和0.45g/g,分别达到理论值的96.1%和86.0%。在含有不同浓度梯度的糠醛及5-羟甲基糠醛的模拟水解液中,Y1和Y4能耐受的最高糠醛浓度均为5.0g/L及最高的5-羟甲基糠醛浓度均大于7.0g/L,当两种抑制剂等量混合时,两株菌能耐受的最高浓度为4.0g/L,两株菌均有较好的乙醇发酵及耐毒能力。该研究结果为木质纤维素水解液的原位脱毒发酵生产然料乙醇奠定了基础。     

汽爆玉米秸秆乙醇发酵残留物产甲烷特性研究

为阐明木质纤维素原料乙醇发酵残留物产甲烷的能力,以汽爆玉米秸秆为原料进行高底物浓度同步糖化发酵(SSF)产乙醇,并将乙醇发酵残留物、发酵残留物上清及固体部分分别进行产甲烷潜力实验。研究结果表明,汽爆玉米秸秆同步糖化发酵底物浓度达到30%(w/w),乙醇浓度为48.9g/L。发酵残留物产甲烷潜力为46mL CH_4/g底物,上清部分产甲烷潜力为12mL CH_4/g底物,固体部分产甲烷潜力达到286mL CH_4/g底物,从而证明高底物浓度汽爆玉米秸秆乙醇发酵残留物具有较好的产甲烷潜力。     

甘蔗渣高温同步糖化发酵制取燃料乙醇研究

研究添加不同量纤维素酶对甘蔗渣酶解效果的影响,结果表明葡萄糖浓度随加酶量增加而增加,最优的添加量为30FPU/(g原料)。利用克鲁维氏酵母(Kluyveromyces marxianus)NCYC 587,在42℃下进行甘蔗渣高温同步水解糖化发酵实验,发现额外添加β-葡萄糖苷酶能有效提高乙醇的质量浓度,经48h发酵,添加30IU/(g葡聚糖)的β-葡萄糖苷酶可提高乙醇浓度30%。通过分批补料方式提高固体浓度至20%,比较SSF和SHF两种工艺,发现前者经72h可产生36.2g/L乙醇,发酵效率为0.50g/(L·h),后者经120h可获得41.2g/L乙醇,发酵效率为0.34g/(L·h)。     

优良酵母菌的筛选、鉴定及发酵生产乙醇的研究

从几种可能富含发酵木糖-葡萄糖酵母菌的材料中分离得到68株酵母菌,分别对其发酵、产乙醇、耐乙醇、木糖利用及木糖-葡萄糖发酵能力进行研究,筛选出发酵木糖-葡萄糖能力较强的酵母菌株。通过镜检观察、耐渗透压、耐受pH值、同化碳源和氮源试验,研究筛选菌株的形态和生理特性,并通过26S rRNA序列测定及系统进化分析对其进行分子鉴定,最后利用木糖-葡萄糖发酵培养基进行产乙醇试验。结果表明:分离菌株中S3和Y4菌株发酵木糖-葡萄糖能力较强,经分子鉴定分别为异常毕赤酵母(Pichia anomala)和热带假丝酵母(Candida tropicalis)。菌株Y4和对照菌株酿酒酵母(Saccharomyces cerevisiae)(N)产乙醇能力显著高于菌株S3(P0.05),且菌株Y4和N间无显著差异(P0.05);而S3与N组合其乙醇产量显著高于菌株Y4,N,S3单独及Y4与N组合,但显著低于S3与Y4组合及S3,N,Y4三者组合(P0.05),其中三者组合的乙醇产量最高,为39.74 g/L。     

稀硫酸-亚硫酸盐法预处理枯死松木的原位纤维素乙醇生产

报道了稀硫酸-亚硫酸盐法预处理软木的纤维素乙醇生产效率。通过采用一株耐受代谢抑制剂的酿酒酵母菌株Y5,对预处理后的固体酶解物及水解液的混合物进行批式及补料批式同步糖化发酵的研究。结果表明:预处理软木混合物中的所有可发酵糖能够在72h内被Y5全部利用,最后的乙醇浓度达到22.2g/L,相应的乙醇发酵产率为0.44g/g。批式与补料批式SSF,除了补料批式发酵24h内的乙醇生产速率高于批式发酵外,并没有其他明显区别。     

两株高效代谢木质纤维素稀酸水解物产乙醇的酵母特性及耐毒研究

对实验室筛选出的两株高效代谢木质纤维素稀酸水解液产乙醇的酵母菌Y1(Candida tropicalis)和Y4(Issatchenkiaorientalis)的乙醇发酵特性及耐毒能力进行了的研究。以未经任何脱毒处理的木质纤维素稀酸水解液为发酵底物进行乙醇发酵(原位脱毒乙醇发酵)。结果表明,Y1和Y4均能在24h内将水解液中所有的葡萄糖消耗完,乙醇产率分别为0.49g/g和0.45g/g,分别达到了理论值的96.1%和86.0%。在含有不同浓度梯度的糠醛及5-羟甲基糠醛的模拟水解液中,Y1和Y4能耐受的最高糠醛浓度均为5.0g/L,最高的5-羟甲基糠醛浓度均大于7.0g/L,当两种抑制剂等量混合时,两株菌能耐受的最高浓度为4.0g/L。两株菌均有较好的乙醇发酵及耐毒能力。该研究结果为木质纤维素水解液的原位脱毒发酵生产然料乙醇奠定了基础。     

Valorization of Eucalyptus wood by glycerol-organosolv pretreatment within the biorefinery concept: An integrated and intensified approach

The efficient utilization of lignocellulosic biomass and the reduction of production cost are mandatory to attain a cost-effective lignocellulose-to-ethanol process. The selection of suitable pretreatment that allows an effective fractionation of biomass and the use of pretreated material at high-solid loadings on saccharification and fermentation (SSF) processes are considered promising strategies for that purpose. Eucalyptus globulus wood was fractionated by organosolv process at 200 °C for 69 min using 56% of glycerol-water. A 99% of cellulose remained in pretreated biomass and 65% of lignin was solubilized. Precipitated lignin was characterized for chemical composition and thermal behavior, showing similar features to commercial lignin. In order to produce lignocellulosic ethanol at high-gravity, a full factory design was carried to assess the liquid to solid ratio (3–9 g/g) and enzyme to solid ratio (8–16 FPU/g) on SSF of delignified Eucalyptus. High ethanol concentration (94 g/L) corresponding to 77% of conversion at 16FPU/g and LSR = 3 g/g using an industrial and thermotolerant Saccharomyces cerevisiae strain was successfully produced from pretreated biomass. Process integration of a suitable pretreatment, which allows for whole biomass valorization, with intensified saccharification-fermentation stages was shown to be feasible strategy for the co-production of high ethanol titers, oligosaccharides and lignin paving the way for cost-effective Eucalyptus biorefinery.     

双菌比较优化稻草“液化”发酵产乙醇的研究

利用稻草液化产物为底物,分别采用酿酒酵母和休哈塔假丝酵母发酵生产乙醇,对影响发酵阶段的各因素进行优化,选取最佳菌种完成秸秆到乙醇的转化。结果表明,液化产物经酶解后葡萄糖浓度可达69.5mg/mL,是发酵制备乙醇的良好底物。优化发酵后,酿酒酵母更适合做液化产物的发酵菌种。适宜的发酵条件:初始葡萄糖浓度60~65 mg/mL,温度30℃,pH=6.0,装液量80 mL,接种量10%,发酵时间36 h,在此条件下乙醇得率可达49.3%,能达到理论得率的96.1%,转化率最高为0.27 g/g(乙醇/液化产物)。     

Evaluation of an adapted inhibitor-tolerant yeast strain for ethanol production from combined hydrolysate of softwood

In order to evaluate the potential of an adapted inhibitor-tolerant yeast strain developed in our lab to produce ethanol from softwood, the effect of furfural and HMF presented in defined medium and pretreatment hydrolysate on cell growth was investigated. And the efficiency of ethanol production from enzymatic hydrolysate mixed with pretreatment hydrolysate of softwood by bisulfite and sulfuric acid pretreatment process was reported. The results showed that in the combined treatments of the two inhibitors, cell growth was not affected at 1 g/L each of furfural and HMF. When 3 g/L each of furfural and HMF was applied, the adapted strain responded with an extended lag phase of 24 h. Both in batch and fed-batch runs of combined hydrolysate fermentation, the final ethanol concentrations were above 20.0 g/L and the ethanol yields (Y_p/s) on the total amount of fermentable sugar presented in the pretreated materials were above 0.40 g/g. It implies the great promise of the yeast strain for improving ethanol production from softwood due to its high ability of metabolizing inhibitor compounds of furfural and HMF.     

提高木糖代谢能力的酿酒酵母Y5-X3的初步构建

为获得能够发酵木糖和葡萄糖的新菌种,文中采用实验室专利菌株Saccharomyces cerevisiae Y5为宿主菌,分别采用热带假丝酵母(Candida tropicalis)和休哈塔假丝酵母(Candida shehatae)作为木糖代谢关键酶XYL1,XYL2的来源,利用酵母整合载体将XYL1,XYL2基因导入S.cerevisiae Y5基因组,同时超表达S.cerevisiae Y5内源木酮糖激酶基因XKS1,获得了酿酒酵母新菌种S.cerevisiae Y5-X3。结果表明,S.cere-visiae Y5-X3在摇瓶共发酵3%葡萄糖和2%木糖时能够利用木糖产乙醇,木糖消耗量和乙醇产量分别比宿主菌提高102.93%和12.54%,发酵2%木糖时木糖的消耗量是宿主菌的2.7倍。XKS1基因的超表达促进了木糖代谢,大大减少了木糖醇积累,提高了乙醇产量。     

Fuel ethanol production from steam-pretreated corn stover using SSF at higher dry matter content

Replacing fossil fuels by bio-fuels has many advantages, such as the reduction of CO₂-emission to the atmosphere, the possibility for non-oil-producing countries to be self-sufficient in fuel, and increased local job opportunities. Bio-ethanol is such a promising renewable fuel. However, today it is produced from sugar or starch—raw materials that are relatively expensive. To lower the production cost of bio-ethanol the cost of the raw material must be reduced and the production process made more efficient. The production of bio-ethanol from corn stover using simultaneous saccharification and fermentation (SSF) at high dry matter content addresses both issues. Corn stover is an agricultural by-product and thus has a low economic value. SSF at high dry matter content results in a high ethanol concentration in the fermented slurry, thereby decreasing the energy demand in the subsequent distillation step.In this study, SSF was performed on steam-pretreated corn stover at 5, 7.5 and 10% water-insoluble solids (WIS) with 2 g/L hexose-fermenting Saccharomyces cerevisiae (ordinary compressed baker's yeast). SSF at 10% WIS resulted in an ethanol yield of 74% based on the glucose content in the raw material and an ethanol concentration of 25 g/L. Neither higher yeast concentration (5 g/L) nor yeast cultivated on the liquid after the pretreatment resulted, under these conditions, in a higher overall ethanol yield.     

复合材料输电线杆应力－应变关系研究

采用自制的复合材料动态变温拉伸实验装置,研究了玻璃布-环氧层板（GFRP）在0℃、-30℃低温环境下的冲击拉伸力学性能,获得了在0℃、-30℃时GFRP材料的动、静态拉伸力学性能参数。结果表明：在10％到1/s应变率范围和低温条件下GFRP材料具有明显的应变率效应和温度效应。在低温环境下,当应变速率提高时,拉伸强度明显增大;和室温情形相比,在低温环境下,GFRP材料的拉伸强度有所提高。实验还发现,在低温环境下GFRP材料具有动态韧性。     

Bioethanol production from pretreated Miscanthus floridulus biomass by simultaneous saccharification and fermentation

The production of ethanol from the fast-growing perennial C4 grass Miscanthus floridulus by simultaneous saccharification and fermentation (SSF) was investigated. M. floridulus biomass was composed of 36.3% glucan, 22.8% hemicellulose, and 21.3% lignin (based on dried mass). Prior to SSF, harvested stems of M. floridulus were pretreated separately by alkali treatment at room temperature, alkali treatment at 90 °C, steam explosion, and acid-catalyzed steam explosion. The delignification rates were determined to be 73.7%, 61.5%, 42.7%, and 63.5%, respectively, by these four methods, and the hemicellulose removal rates were 51.5%, 85.1%, 70.5%, and 97.3%, respectively. SSF of residual solids after various pretreatments was performed with dried yeast (Saccharomyces cerevisiae) and cellulases (Accellerase 1000) by using 10% water-insoluble solids (WIS) of the pretreated M. floridulus as the substrate. The ethanol yields from 72-h SSF of M. floridulus biomass after these pretreatments were 48.9 ± 3.5, 78.4 ± 1.0, 46.4 ± 0.1, and 69.0 ± 0.1% (w/w), respectively, while the ethanol concentrations after 72-h SSF were determined to be 15.4 ± 1.1, 27.5 ± 0.3, 13.9 ± 0.1, and 30.8 ± 0.1 g/L, respectively. Overall, the highest amount of ethanol (0.124 g/g-dried raw material) was generated from dried raw material of M. floridulus after alkaline pretreatment at 90 °C. The acid-catalyzed steam explosion pretreatment also resulted in a high ethanol yield (0.122 g/g-dried raw material). Pretreatment resulting in high lignin and hemicellulose removal rates could make biomass more accessible to enzyme hydrolysis and lead to higher ethanol production.     

酵母菌复合培养物对木质纤维素稀酸水解液原位脱毒乙醇发酵

为了解决木质纤维素稀酸水解产物中发酵抑制剂对微生物的抑制作用以及木糖的乙醇发酵问题,该研究用本实验室开发的能高效代谢葡萄糖产乙醇并代谢糠醛和5-羟甲基糠醛的2株酵母菌种Saccharomyces cerevisiae Y5和Ismtchenkia/orientalis Y4分别与Pichia.stipitis CBS6054组成2个复合菌种,用复合菌种对木质纤维素稀酸水解产物进行原位脱毒乙醇发酵.结果证明,复合菌种S.cerevisiae Y5,P.stipitis CBS6054显示出了很好的代谢稀酸水解液中的葡萄糖和木糖产乙醇并快速代谢糠醛和5-羟甲基糠醛的能力,乙醇产率为0.43g/g(达到理论值的85.1%).该复合培养物可作为木质纤维索稀酸水解产物不需任何脱毒处理直接进行乙醇发酵的复合菌种.