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排序方式: 共有91条查询结果,搜索用时 15 毫秒
1.
Spindler Diane D. Wyman Charles E. Grohmann Karel 《Applied biochemistry and biotechnology》1991,(1):773-786
Four promising woody crops (Populusmaximowiczii x nigra (NE388), P.trichocarpa x deltoides (Nll), P.tremuloides, and SweetgumLiquidambar styraciflua) were pretreated by dilute sulfuric acid and evaluated in the simultaneous saccharification and fermentation (SSF) process
for ethanol production. The yeastSaccharomyces cerevisiae was used in the fermentations alone, and in mixed cultures with β -glucosidase producingBrettanomyces dausenii. Commercial Genencor 150L cellulase enyme was either employed alone or supplemented with β- glucosidase. All SSFs were run at 37 …C for 8 d and compared to saccharifications at 45…C under the same enzyme loadings.S. cerevisiae alone achieved the highest ethanol yields and rates of hydrolysis at the higher enzyme loadings, whereas the mixed culture
performed better at the lower enzyme loadings without β -glucosidase supplementation. The best overall rates of fermentation
(3 d) and final theoretical ethanol yields (86–90%) were achieved with P.maximowiczii x nigra (NE388) and SweetgumLiquidambar styraciflua, followed by P.tremuloides and P.trichocarpa xdeltoides (N1l) with slightly slower rates and lower yields. Although there were some differences in SSF performance, all these pretreated
woody crops show promise as substrates for ethanol production. 相似文献
2.
Ballesteros I. Ballesteros M. CabaÑas A. Carrasco J. MartÍn C. Negro M. J. Saez F. Saez R. 《Applied biochemistry and biotechnology》1991,(1):307-315
A total of 27 yeast strains belonging to the groupsCandida, Saccharomyces, andKluyveromyces were screened for their ability to grow and ferment glucose at temperatures ranging 32-45°C.
K. marxianus andK. fragilis were found to be the best ethanol producing organisms at the higher temperature tested and, so, were selected for subsequent
simultaneous saccharification and fermentation (SSF) studies. 相似文献
3.
The acetone-butanol production by simultaneous saccharification and extractive fermentation (SSEF) was investigated. In the
SSEF employing cellulase enzymes andClostridium acetobutylicum, both glucan and xylan fractions of pretreated aspen are concurrently converted into acetone and butanol. Continuous removal
of the fermentation products from the bioreactor by extraction was an important factor that allowed long-term fed-batch operation.
The use of membrane extraction prevented the problems of phase separation and extractant loss. Increase in substrate feeding
as well as reduction of nutrient supply was found to be beneficial in suppressing the acid production, thereby improving the
solvent yield. Because of prolonged low growth conditions prevalent in the fed-batch operation, the butanol-to-acetone ratio
in the product was significantly higher at 2.6–2.8 compared to the typical value of two. 相似文献
4.
发现玉米淀粉的酶糖化反应,可以用酶的三态模型描述,而且该反应具有单底物酶动力学犍征。用三态模型导出的反应动力学模型式计算反应速度等参数,其计算结果实验数据基本一致。 相似文献
5.
Ultrasound (US) can be used to disrupt microcrystalline cellulose to give nanofibers via ultrasonic cavitation. Sodium percarbonate (SP), consisting of sodium carbonate and hydrogen peroxide, generates highly reactive radicals, which cause oxidative delignification. Here, we describe a novel pretreatment technique using a combination of US and SP (US–SP) for the efficient saccharification of cellulose and hemicellulose in lignocellulosic corn stover. Although US–SP pretreatment was conducted under mild condition (i.e., at room temperature and atmospheric pressure), the pretreatment greatly increased lignin removal and cellulose digestibility. We also determined the optimum US–SP treatment conditions, such as ultrasonic power output, pretreatment time, pretreatment temperature, and SP concentration for an efficient cellulose saccharification. Moreover, xylose could be effectively recovered from US–SP pretreated biomass without the formation of microbial inhibitor furfural. 相似文献
6.
Cao Ningjun Xia Youkun Gong Cheng S. Tsao George T. 《Applied biochemistry and biotechnology》1997,(1):129-139
A simple and effective method of treatment of lignocellulosic material was used for the preparation of corn cob for the production
of 2,3-butanediol byKlebsiella oxytoca ATCC 8724 in a simultaneous saccharification and fermentation process. During the treatment, lignin, and alkaline extractives
were solubilized and separated from cellulose and hemicellulose fractions by dilute ammonia (10%) steeping. Hemicellulose
was then hydrolyzed by dilute hydrochloric acid (1%, wJv) hydrolysis at 100°C at atmospheric pressure and separated from cellulose
fraction. The remaining solid, with 90% of cellulose, was then used as the substrate. A butanediol concentration of 25 g/L
and an ethanol concentration of 7 g/L were produced byK. oxytoca from 80 g/L of corn cob cellulose with a cellulase dosage of 8.5 IFPU/g corn cob cellulose after 72 h of SSF. With only dilute
acid hydrolysis, a butanediol production rate of 0.21 g/L/h was obtained that is much lower than the case in which corn cob
was treated with ammonia steeping prior to acid hydrolysis. The butanediol production rate for the latter was 0.36 g/L/h. 相似文献
7.
8.
王金凤 《北京工商大学学报(自然科学版)》1993,(1)
本文综合了国内外啤酒糖化生产过程控制的现状,指出在我国对啤酒糖化生产过程进行技术改造实现自动控制的必要性和可行性,介绍了国内外两个系统的主要性能和计算机控制的发展方向,提出了适合我国国情的分两步走的啤酒糖化计算机控制的实施方案,给出了有关系统的框图. 相似文献
9.
Effectiveness factors were predicted from measurements of basic parameters made on single oligosaccharides, and the prediction
was compared to experimental effec tiveness factors for the reaction of each oligosaccharide in the immobilized enzyme catalyst.
Kinetic parameters were obtained for the hydrolysis of each oligosaccharide catalyzed by soluble glucoamylase, and were fit
with a subsite model equation capable of generalization to all sizes of oligosaccharide. Diffusion coefficients in free solution
were determined from movement out of a capillary tube. Spatial characteristics of the immobilized enzyme bed were obtained
from pulse response experiments, allowing the calculation of effective diffusivities. Experimental effectiveness factors plotted
against modulus were in reasonable agreement with the predictions. 相似文献
10.
【目的】对多粘类芽孢杆菌Paenibacillus polymyxa的玉米粉同步糖化发酵工艺进行优化,以获得低成本、高效的(R,R)-2,3-丁二醇生产技术。【方法】研究玉米粉浓度、氮源种类和氮源浓度对菌体生长、耗糖能力以及(R,R)-2,3-丁二醇产量、产率、得率和转化率的影响,并在此基础上进一步考察培养基中其它成分对(R,R)-2,3-丁二醇发酵的影响。【结果】优化后的培养基组分为玉米干粉140g/L,酵母粉30g/L,Na_2HPO_4 3g/L,KH_2PO_43g/L,(NH_4)2SO_42g/L,MgSO_40.8g/L,微量元素溶液2mL/L。使用优化后的培养基进行同步糖化发酵,发酵50h后(R,R)-2,3-丁二醇产量达到56.28g/L(光学纯度为98.3%),对葡萄糖的得率为0.44g/g,产率为1.13g/(L·h)。【结论】(R,R)-2,3-丁二醇生产技术低价高效,可为其工业化生产提供参考。 相似文献