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以解纤维梭菌( Clostridium cellulolyticum)和热纤梭菌( Clostridium thermocellum)为代表的产纤维小体梭菌可以直接完成从木质纤维素原料到乙醇的生物转化,是用于通过整合生物加工技术生产纤维素乙醇的优良候选菌株。然而,这些产纤维小体梭菌的纤维素降解效率及乙醇产量尚不能满足工业化生产的要求,其遗传改造技术的不成熟严重制约了通过定向代谢工程改造提高生产性能的进程。针对这些典型的产纤维小体菌株,各国科学家近年来在基于二类内含子的嗜中温及嗜高温遗传改造平台建立方面取得了较大突破,并通过靶向代谢工程改造,显著提高纤维素乙醇的产量。笔者对这些前期研究工作以及国内外相关研究成果进行系统的总结,并对构建的遗传改造工具的应用前景进行展望。 相似文献
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纤维素乙醇的统合生物加工过程(consolidated bioprocessing,CBP)是将(半)纤维素酶生产、纤维素水解和乙醇发酵过程组合,通过一种微生物完成的生物加工过程。 CBP有利于降低生物转化过程的成本,受到研究者的普遍关注。酿酒酵母( Saccharomyces cerevisiae)作为传统的乙醇生产菌株,是极具潜力的CBP底盘细胞。纤维小体是某些厌氧微生物细胞表面由纤维素酶系与支架蛋白组成的大分子复合物,它能高效降解木质纤维,在酿酒酵母表面展示纤维小体已成为构建CBP细胞的研究热点。笔者综述了人造纤维小体在酿酒酵母细胞表面展示组装的研究进展,重点阐述了纤维小体各元件的设计和改造,并针对酿酒酵母分泌途径的改造,提出提高人造纤维小体分泌组装的可能性策略。 相似文献
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极端嗜热厌氧菌 Caldicellulosiruptor 木质纤维素降解研究简 总被引:1,自引:0,他引:1
随着能源危机的加剧,木质纤维素作为生产生物能源的重要原料得到人们的广泛关注。目前,极端嗜热厌氧菌Caldicellulosiruptor属已发现8个种,具有高效的木质纤维素降解能力,甚至可以作用于未经预处理的木质纤维素。自从20世纪80年代以来,人们在Caldicellulosiruptor属的菌株生理生化性质、木质纤维素降解机制及转化能力、基因组、转录组及蛋白质组、遗传转化体系等方面,都取得了一系列研究成果。笔者对嗜热厌氧菌Caldicellulosiruptor属木质纤维素降解的研究现状及前景进行综述及展望。 相似文献
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粗糙脉孢菌作为木质纤维素降解真菌,不仅具有完整的木质纤维素降解酶系,而且还拥有全基因组基因敲除突变体库,是研究丝状真菌纤维素酶表达分泌和木质纤维素降解机制的优秀体系。近年来,国内外利用粗糙脉孢菌系统,在木质纤维素降解机制方面取得了显著进展,包括纤维素酶信号传导、调控以及生物质降解后糖的转运利用等。笔者就相关方面的进展进行综述,并对利用粗糙脉孢菌研究木质纤维素降解利用进行展望,总结和分析木质纤维素降解机制研究的国际前沿动态,有助于加深本领域研究人员对真菌体系纤维素降解机制的理解。 相似文献
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黄翅大白蚁( Macrotermes barneyi)具有高效降解木质纤维素的能力,其后肠内存在着丰富的共生微生物。采用活性电泳和变形梯度凝胶电泳的方法对黄翅大白蚁后肠降解滤纸微生物群落进行分析。活性电泳实验证实了此微生物群落纤维素酶的存在(内切葡聚糖酶、β葡萄糖苷酶和木聚糖酶),变形梯度凝胶电泳实验鉴定出微生物组的群落结构,即7种细菌和3种真菌。本研究初步阐明了黄翅大白蚁后肠内与滤纸降解相关的微生物种类,为进一步了解黄翅大白蚁纤维素的降解机制以及生物质资源的高效利用提供了理论基础。 相似文献
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以抗逆突变株Clostridium beijerinckii IB4为出发菌株,通过常压室温等离子体诱变( ARTP ),刃天青平板初筛,摇瓶发酵复筛,筛选出1株高抗逆高丁比的突变菌株C.beijerinckii IT111。发酵结果表明:该突变菌株利用多种C源时均展现其高丁醇比的特性,以玉米芯酸解糖液为C源时,溶剂产量达到10.5 g/L,丁醇8.0 g/L,丁醇比高达76%。抑制物抗逆性测试结果显示:糠醛和酸类对C.beijerinckii发酵影响较小,酚类物质对C.beijerinckii抑制作用较强,其中以香草醛为最。综上所述,C.beijerinckii IT111是1株极具潜力的利用木质纤维原料制备丁醇的菌株。 相似文献
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Toru Ikegamai Hiroshi Yanagishita Dai Kitamoto Kenji Haraya 《Biotechnology letters》2000,22(21):1661-1665
Fermentation with the addition of activated carbon at 100 g l–1 promoted the glucose consumption and ethanol production rates of Saccharomyces cerevisiae by 1.3 and 1.1 times, respectively. With fermentation using spent medium, the consumption rate was maintained at 90% of that in the fresh medium with the addition of activated carbon, while the rate without any addition decreased to about 70%. 相似文献
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Virginie Ansanay-Galeote Bruno Blondin Sylvie Dequin Jean-Marie Sablayrolles 《Biotechnology letters》2001,23(9):677-681
When 4% (v/v) ethanol was added progressively to two strains exhibiting different fermentative abilities, K1 (a commercial wine strain) and V5 (a strain derived of a wine yeast), the fermentation rate correlated directly to the ethanol concentration for both strains. In contrast, the effect of sudden addition of 2%, 4% or 6% (v/v) ethanol was different depending on the strain. While the same effect was observed for K1 whatever the way of ethanol addition, V5 required an adaptation period after the shock addition of ethanol. 相似文献
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《Critical reviews in biotechnology》2013,33(1):22-48
Lignocellulosic biomass from agricultural and agro-industrial residues represents one of the most important renewable resources that can be utilized for the biological production of ethanol. The yeast Saccharomyces cerevisiae is widely used for the commercial production of bioethanol from sucrose or starch-derived glucose. While glucose and other hexose sugars like galactose and mannose can be fermented to ethanol by S. cerevisiae, the major pentose sugars D-xylose and L-arabinose remain unutilized. Nevertheless, D-xylulose, the keto isomer of xylose, can be fermented slowly by the yeast and thus, the incorporation of functional routes for the conversion of xylose and arabinose to xylulose or xylulose-5-phosphate in Saccharomyces cerevisiae can help to improve the ethanol productivity and make the fermentation process more cost-effective. Other crucial bottlenecks in pentose fermentation include low activity of the pentose phosphate pathway enzymes and competitive inhibition of xylose and arabinose transport into the cell cytoplasm by glucose and other hexose sugars. Along with a brief introduction of the pretreatment of lignocellulose and detoxification of the hydrolysate, this review provides an updated overview of (a) the key steps involved in the uptake and metabolism of the hexose sugars: glucose, galactose, and mannose, together with the pentose sugars: xylose and arabinose, (b) various factors that play a major role in the efficient fermentation of pentose sugars along with hexose sugars, and (c) the approaches used to overcome the metabolic constraints in the production of bioethanol from lignocellulose-derived sugars by developing recombinant S. cerevisiae strains. 相似文献
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Petra Bafrncová Daniela šmogrovičová Iveta Sláviková Jaroslava Pátková Zoltán Dömény 《Biotechnology letters》1999,21(4):337-341
The final ethanol concentration achieved was increased by 17% (to 103 g ethanol/l) when excess assimilable nitrogen was added to the batch very high gravity (VHG) ethanolic fermentations by Saccharomyces cerevisiae. The supplementation of the media with 12 g yeast extract l–1, 0.3 g cell walls l–1, 3 g glycine l–1 and 20 g soya flour l–1 led to halving reduction of the fermentation time to 28 h. The ethanol productivity was enhanced by more than 50% (to achieved value 3.3 g l–1 h–1). 相似文献
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VariousSaccharomyces cerevisiae strains were transformed with a 2 μ-based multicopy expression plasmid, pYIGP, carryingKluyveromyces marxianus inulinase gene under the control ofGAPDH promoter. Among them two strains, SEY2102 and 2805, showed high levels of cell growth and inulinase expression, and were
selected to study their fermentation properties on inulin. Jerusalem artichoke inulin was more effective for cell growth (10∼11
g-dry wt./L at 48 hr) and inulinase expression (1.0 units/mL with SEY2102/pYIGP and 2.5 units/mL with 2805/pYIGP) than other
inulin sources such as dahlia and chicory. It was also found that maximal ethanol production of 9 g/L was obtained from Jerusalem
artichoke inulin at the early stationary phase (around 30 hr), indicating that recombinantS. cerevisiae cells secreting exoinulinase could be used for the simultaneous saccharification of inulin and ethanol fermentation. 相似文献
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Production of ethanol from L-arabinose by Saccharomyces cerevisiae containing a fungal L-arabinose pathway 总被引:2,自引:0,他引:2
The fungal pathway for L-arabinose catabolism converts L-arabinose to D-xylulose 5-phosphate in five steps. The intermediates are, in this order: L-arabinitol, L-xylulose, xylitol and D-xylulose. Only some of the genes for the corresponding enzymes were known. We have recently identified the two missing genes for L-arabinitol 4-dehydrogenase and L-xylulose reductase and shown that overexpression of all the genes of the pathway in Saccharomyces cerevisiae enables growth on L-arabinose. Under anaerobic conditions ethanol is produced from L-arabinose, but at a very low rate. The reasons for the low rate of L-arabinose fermentation are discussed. 相似文献
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Improved ethanol tolerance of Saccharomyces cerevisiae strains by increases in fatty acid unsaturation via metabolic engineering 总被引:2,自引:0,他引:2
Susumu Kajiwara Keiko Suga Hidetaka Sone Katsumi Nakamura 《Biotechnology letters》2000,22(23):1839-1843
To enhance the ethanol tolerance of Saccharomyces cerevisiae, the Arabidopsis thaliana FAD2 gene and/or the S. cerevisiae OLE1 gene were over-expressed in this yeast. The transformant over-expressing both these genes could not only synthesize dienoic fatty acids but also increased the unsaturated fatty acid content of membrane lipid and then showed the highest viability in the presence of 15% (v/v) ethanol. 相似文献