共查询到20条相似文献,搜索用时 140 毫秒
1.
2.
3.
植物组织培养方法生产药用次生代谢产物研究进展 总被引:2,自引:0,他引:2
赵春梅 《现代生物医学进展》2008,8(4):790-792
许多药物来源于植物次生代谢途径,目前植物组织培养方法已成为生产药用成分的重要手段.在植物组织培养中,选择高产的外植体,寻找合适的培养条件,运用两相培养法和毛状根培养技术以及控制组织培养过程中的污染、褐化及玻璃化等问题,则是提高植物细胞生长速度和次生代谢产物产量并实现工业化生产的先决条件.本文主要从以上几个方面介绍其近来的研究进展,并提出了存在的问题及解决对策. 相似文献
4.
5.
【背景】天蚕素抗菌肽是目前研究最清楚、效果最显著的抗菌肽,实现工业化生产为其在农业、养殖业中的应用奠定了基础。【目的】获得一株高效生产天蚕素AD的基因工程菌株。【方法】构建重组载体pGAPZαA-CAD通过电击转化至PichiapastorisX33中,表达天蚕素AD基因并获得X33/GCAD菌株;构建重组载体pUCGAP-CAD导入至X33/GCAD菌株中。pGAPZαA-CAD是以博来霉素为抗性筛选标签被整合到P. pastoris X33的GAPDH启动子区域,pUCGAP-CAD是以遗传霉素为抗性筛选标签被整合到P. pastoris X33的非翻译rDNA区域,最终获得一株高效表达天蚕素AD的酵母菌株X33/GUCAD。【结果】通过质谱分析鉴定X33/GUCAD表达的抑菌物质为天蚕素AD,通过发酵条件的优化,表明X33/GUCAD菌株在以甘油为碳源和以蛋白胨、酵母提取物为有机氮源的情况下具有较强表达天蚕素AD的能力。【结论】较高的拷贝数更有利于提高天蚕素AD的产量,此工程菌株在后期发酵过程中稳定性较好,适于工业化生产。 相似文献
6.
7.
8.
9.
海藻糖生产菌株筛选过程中产物鉴定的研究 总被引:4,自引:0,他引:4
在海藻糖生产菌的筛选过程中,微生物胞内酶转化淀粉生成的产物复杂,将产物逐一纯化是非常烦琐的,但又必须确证产物中是否含有海藻糖。本文将薄层层析、高效液相电喷雾电离质谱联用及核磁共振等分析手段综合应用于海藻糖生产菌株的筛选,在酶反应产物不必被纯化的前提下,准确、快捷地鉴定了酶反应产物中的未知糖组分,最终证明食尼古丁节杆菌(Arthrobacter nicotinovorus)D97利用淀粉或麦芽寡糖的酶反应产物中含有海藻糖。该方法在筛选海藻糖及其它功能性葡二糖生产菌株时较为严密。 相似文献
10.
一株高产木聚糖酶的枝链霉菌的分离鉴定及产酶 总被引:4,自引:0,他引:4
对1株高产木聚糖酶的链霉菌进行了鉴定并研究其木聚糖酶的生产过程及水解产物特点。分离得到1株产木聚糖酶的链霉菌Streptomyces sp.L2001,从形态学特征、培养特征和生理生化特征等方面对该菌株进行了鉴定。PCR扩增得到16S rDNA序列全长为1429bp,分析结果表明,菌株与Streptomyces rameus NBRC3782同源性达99.16%。结合传统生理生化实验结果鉴定为枝链霉菌。菌株液体发酵6d能产生842.0U/mL木聚糖酶活力。经HPLC分析酶解产物,结果显示木二糖、木三糖及木四糖含量之和高达93.5%,该酶适用于工业化生产低聚木糖。 相似文献
11.
12.
China is one of the few countries, which maintained the fermentative acetone–butanol–ethanol (ABE) production for several
decades. Until the end of the last century, the ABE fermentation from grain was operated in a few industrial scale plants.
Due to the strong competition from the petrochemical industries, the fermentative ABE production lost its position in the
1990s, when all the solvent fermentation plants in China were closed. Under the current circumstances of concern about energy
limitations and environmental pollution, new opportunities have emerged for the traditional ABE fermentation industry since
it could again be potentially competitive with chemical synthesis. From 2006, several ABE fermentation plants in China have
resumed production. The total solvent (acetone, butanol, and ethanol) production capacity from ten plants reached 210,000 tons,
and the total solvent production is expected to be extended to 1,000,000 tons (based on the available data as of Sept. 2008).
This article reviews current work in strain development, the continuous fermentation process, solvent recovery, and economic
evaluation of ABE process in China. Challenges for an economically competitive ABE process in the future are also discussed. 相似文献
13.
In the last decades, fermentative production of n-butanol has regained substantial interest mainly owing to its use as drop-in-fuel. The use of lignocellulose as an alternative to traditional acetone–butanol–ethanol fermentation feedstocks (starchy biomass and molasses) can significantly increase the economic competitiveness of biobutanol over production from non-renewable sources (petroleum). However, the low cost of lignocellulose is offset by its high recalcitrance to biodegradation which generally requires chemical-physical pre-treatment and multiple bioreactor-based processes. The development of consolidated processing (i.e., single-pot fermentation) can dramatically reduce lignocellulose fermentation costs and promote its industrial application. Here, strategies for developing microbial strains and consortia that feature both efficient (hemi)cellulose depolymerization and butanol production will be depicted, that is, rational metabolic engineering of native (hemi)cellulolytic or native butanol-producing or other suitable microorganisms; protoplast fusion of (hemi)cellulolytic and butanol-producing strains; and co-culture of (hemi)cellulolytic and butanol-producing microbes. Irrespective of the fermentation feedstock, biobutanol production is inherently limited by the severe toxicity of this solvent that challenges process economic viability. Hence, an overview of strategies for developing butanol hypertolerant strains will be provided. 相似文献
14.
Butanol has been acknowledged as an advanced biofuel, but its production through acetone–butanol–ethanol (ABE) fermentation by clostridia is still not economically competitive, due to low butanol yield and titer. In this article, update progress in butanol production is reviewed. Low price and sustainable feedstocks such as lignocellulosic residues and dedicated energy crops are needed for butanol production at large scale to save feedstock cost, but processes are more complicated, compared to those established for ABE fermentation from sugar- and starch-based feedstocks. While rational designs targeting individual genes, enzymes or pathways are effective for improving butanol yield, global and systems strategies are more reasonable for engineering strains with stress tolerance controlled by multigenes. Compared to solvent-producing clostridia, engineering heterologous species such as Escherichia coli and Saccharomyces cerevisiae with butanol pathway might be a solution for eliminating the formation of major byproducts acetone and ethanol so that butanol yield can be improved significantly. Although batch fermentation has been practiced for butanol production in industry, continuous operation is more productive for large scale production of butanol as a biofuel, but a single chemostat bioreactor cannot achieve this goal for the biphasic ABE fermentation, and tanks-in-series systems should be optimized for alternative feedstocks and new strains. Moreover, energy saving is limited for the distillation system, even total solvents in the fermentation broth are increased significantly, since solvents are distilled to ~ 40% by the beer stripper, and more than 95% water is removed with the stillage without phase change, even with conventional distillation systems, needless to say that advanced chemical engineering technologies can distil solvents up to ~ 90% with the beer stripper, and the multistage pressure columns can well balance energy consumption for solvent fraction. Indeed, an increase in butanol titer with ABE fermentation can significantly save energy consumption for medium sterilization and stillage treatment, since concentrated medium can be used, and consequently total mass flow with production systems can be reduced. As for various in situ butanol removal technologies, their energy efficiency, capital investment and contamination risk to the fermentation process need to be evaluated carefully. 相似文献
15.
Two metabolic engineering tools, namely gene inactivation and gene overexpression, were employed to examine the effects of two genetic modifications on the fermentation characteristics of Clostridium acetobutylicum. Inactivation of the butyrate kinase gene (buk) was examined using strain PJC4BK, while the combined effect of buk inactivation and overexpression of the aad gene-encoding the alcohol aldehyde dehydrogense (AAD) used in butanol formation-was examined using strain PJC4BK(pTAAD). The two strains were characterized in controlled pH > or = 5.0 fermentations, and by a recently enhanced method of metabolic flux analysis. Strain PJC4BK was previously genetically characterized, and fermentation experiments at pH > or = 5.5 demonstrated good, but not exceptional, solvent-production capabilities. Here, we show that this strain is a solvent superproducer in pH > or = 5.0 fermentations producing 225 mM (16.7 g/L) of butanol, 76 mM of acetone (4.4 g/L), and 57 mM (2.6 g/L) of ethanol. Strain PJC4BK(pTAAD) produced similar amounts of butanol and acetone but 98 mM (4.5 g/L) of ethanol. Both strains overcame the 180 mM (13 g/L) butanol toxicity limit, without any selection for butanol tolerance. Work with strain PJC4BK(pTAAD) is the first reported use of dual antibiotic selection in C. acetobutylicum. One antibiotic was used for selection of strain PJC4BK while the second antibiotic selected for the pTAAD presence. Overexpression of aad from pTAAD resulted in increased ethanol production but did not increase butanol titers, thus indicating that AAD did not limit butanol production under these fermentation conditions. Metabolic flux analysis showed a decrease in butyrate formation fluxes by up to 75% and an increase in acetate formation fluxes of up to 100% during early growth. The mean specific butanol and ethanol formation fluxes increased significantly in these recombinant strains, up to 300% and 400%, respectively. Onset of solvent production occurred during the exponential-growth phase when the culture optical density was very low and when total and undissociated butyric acid levels were <1 mM. Butyrate levels were low throughout all fermentations, never exceeding 20 mM. Thus, threshold butyrate concentrations are not necessary for solvent production in these stains, suggesting the need for a new phenomenological model to explain solvent formation. 相似文献
16.
J. Li J.B. Zhao M. Zhao Y.L. Yang W.H. Jiang S. Yang 《Letters in applied microbiology》2010,50(4):373-379
Aims: Poor butanol tolerance of solventogenic stains directly limits their butanol production during industrial‐scale fermentation process. This study was performed to search for micro‐organisms possessing elevated tolerance to butanol. Methods and Results: Two strains, which displayed higher butanol tolerance compared to commonly used solventogenic Clostridium acetobutylicum, were isolated by evolution and screening strategies. Both strains were identified as lactic acid bacteria (LAB). On this basis, a LAB culture collection was tested for butanol tolerance, and 60% of the strains could grow at a butanol concentration of 2·5% (v/v). In addition, an isolated strain with superior butanol tolerance was transformed using a certain plasmid. Conclusions: The results indicate that many strains of LAB possessed inherent tolerance of butanol. Significance and Impact of the Study: This study suggests that LAB strains may be capable of producing butanol to elevated levels following suitable genetic manipulation. 相似文献
17.
Biobutanol: an attractive biofuel 总被引:1,自引:0,他引:1
Dürre P 《Biotechnology journal》2007,2(12):1525-1534
Biofuels are an attractive means to prevent a further increase of carbon dioxide emissions. Currently, gasoline is blended with ethanol at various percentages. However, butanol has several advantages over ethanol, such as higher energy content, lower water absorption, better blending ability, and use in conventional combustion engines without modification. Like ethanol, it can be produced fermentatively or petrochemically. Current crude oil prices render the biotechnological process economic again. The best-studied bacterium to perform a butanol fermentation is Clostridium acetobutylicum. Its genome has been sequenced, and the regulation of solvent formation is under intensive investigation. This opens the possibility to engineer recombinant strains with superior biobutanol-producing ability. 相似文献
18.
Fermentative butanol production by Clostridia 总被引:1,自引:0,他引:1
Lee SY Park JH Jang SH Nielsen LK Kim J Jung KS 《Biotechnology and bioengineering》2008,101(2):209-228
Butanol is an aliphatic saturated alcohol having the molecular formula of C(4)H(9)OH. Butanol can be used as an intermediate in chemical synthesis and as a solvent for a wide variety of chemical and textile industry applications. Moreover, butanol has been considered as a potential fuel or fuel additive. Biological production of butanol (with acetone and ethanol) was one of the largest industrial fermentation processes early in the 20th century. However, fermentative production of butanol had lost its competitiveness by 1960s due to increasing substrate costs and the advent of more efficient petrochemical processes. Recently, increasing demand for the use of renewable resources as feedstock for the production of chemicals combined with advances in biotechnology through omics, systems biology, metabolic engineering and innovative process developments is generating a renewed interest in fermentative butanol production. This article reviews biotechnological production of butanol by clostridia and some relevant fermentation and downstream processes. The strategies for strain improvement by metabolic engineering and further requirements to make fermentative butanol production a successful industrial process are also discussed. 相似文献
19.
Yan-Ning Zheng Liang-Zhi Li Mo Xian Yu-Jiu Ma Jian-Ming Yang Xin Xu Dong-Zhi He 《Journal of industrial microbiology & biotechnology》2009,36(9):1127-1138
With the incessant fluctuations in oil prices and increasing stress from environmental pollution, renewed attention is being
paid to the microbial production of biofuels from renewable sources. As a gasoline substitute, butanol has advantages over
traditional fuel ethanol in terms of energy density and hygroscopicity. A variety of cheap substrates have been successfully
applied in the production of biobutanol, highlighting the commercial potential of biobutanol development. In this review,
in order to better understand the process of acetone–butanol–ethanol production, traditional clostridia fermentation is discussed.
Sporulation is probably induced by solvent formation, and the molecular mechanism leading to the initiation of sporulation
and solventogenesis is also investigated. Different strategies are employed in the metabolic engineering of clostridia that
aim to enhancing solvent production, improve selectivity for butanol production, and increase the tolerance of clostridia
to solvents. However, it will be hard to make breakthroughs in the metabolic engineering of clostridia for butanol production
without gaining a deeper understanding of the genetic background of clostridia and developing more efficient genetic tools
for clostridia. Therefore, increasing attention has been paid to the metabolic engineering of E. coli for butanol production. The importation and expression of a non-clostridial butanol-producing pathway in E. coli is probably the most promising strategy for butanol biosynthesis. Due to the lower butanol titers in the fermentation broth,
simultaneous fermentation and product removal techniques have been developed to reduce the cost of butanol recovery. Gas stripping
is the best technique for butanol recovery found so far. 相似文献
20.
Gu Y Jiang Y Wu H Liu X Li Z Li J Xiao H Shen Z Dong H Yang Y Li Y Jiang W Yang S 《Biotechnology journal》2011,6(11):1348-1357
Butanol is an important solvent and transport fuel additive, and can be produced by microbial fermentation. Attempts to generate a superior microbial producer of butanol have been made through different metabolic engineering strategies. However, to date, butanol bio-production is still not economically competitive compared to petrochemical-derived production because of its major drawbacks, such as, high cost of the feedstocks, low butanol concentration in the fermentation broth and the co-production of low-value by-products acetone and ethanol. Here we analyze the main bottlenecks in microbial butanol production and summarize relevant advances from recently reported studies. Further needs and directions for developing real industrially applicable strains in butanol production are also discussed. 相似文献