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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
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Hong-Jaan Wang Cheng-Huei Hsiong Li-Heng Pao Wen-Liang Chang Li-Jie Zhang Min-Jen Lin Shung-Tai Ho Pei-Wei Huang Oliver Yoa-Pu Hu 《Metabolomics : Official journal of the Metabolomic Society》2014,10(4):709-718
A safe and efficient semi-synthetic narcotic nalbuphine (NAL) which was broadly applied in analgesic therapy has long been considered to eliminate from human body via phase II conjugation. However, up to the present, neither the complete metabolic pathways nor the identified metabolites of NAL have been clarified in documented reports. In this study, four novel metabolites were discovered by incubating NAL with human liver microsomes. These metabolites were later quantified in blood samples from human volunteers treated with NAL. An accurate and precise new method for simultaneously determining NAL and its metabolites was also established. Their chemical structures were elucidated on the basis of one- and two-dimensional NMR spectroscopic analyses including 1H–1H correlation spectroscopy, nuclear overhauser enhancement spectroscopy, heteronuclear single-quantum correlation, and heteronuclear multiple bond correlation, and further confirmed by mass spectrometry. The analytical method was validated and applied successfully to a pilot human study with ultra-high performance liquid chromatography–tandem mass spectrometry employed with positive ion electrospray ionization via multiple reaction monitoring mode. This is the first report on the qualitative and quantitative analysis of NAL coupled with its two hydroxylated (3′-hydroxynalbuphine and 4′-hydroxynalbuphine) and two conjugated metabolites (nalbuphine-3-β-d-glucuronide and nalbuphine-6-β-d-glucuronide). The present method offers a rapid and simple way of performing pharmacokinetic studies of NAL, and assists in elucidating its metabolic pathway in humans. 相似文献
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以抗寒品种‘东衣冬麦l号’和冷敏感品种‘济麦22’为试验材料,在三叶期时对叶片喷施ABA。在冬小麦越冬期间对叶片和分蘖节取样,研究外源ABA对越冬期低温下冬小麦的蔗糖含量及蔗糖代谢相关酶活性的影响。结果表明,外源ABA处理使低温下2个冬小麦品种积累了更多的蔗糖,尤其是‘东农冬麦1号’的分蘖节。零上低温时外源ABA促进了尿苷二磷酸一葡萄糖焦磷酸化酶(UGP)在蔗糖的合成中起主要作用,在零下低温时外源ABA则促进了UGP在蔗糖分解中起作用;外源ABA提高了‘东农冬麦1号’叶片和分蘖节以及‘济麦22’分蘖节中蔗糖磷酸合成酶、蔗糖合成酶的活性,但‘济麦22’叶片中这两种酶的活性则受到ABA的抑制;外源ABA也不同程度地促进了2+-小麦品种叶片和‘济麦22’分蘖节中酸性转化酶和碱性转化酶活性的提高,但却抑制了‘东农冬麦1号’分蘖节中两种酶活性的提高,表明抗寒性强的‘东农冬麦1号’对外源ABA可能更加敏感,其越冬器官分蘖节保持了较高的蔗糖水平,其蔗糖合成能力的提高将有利于冬小麦植株抵御低温,进而维持+a+k-的存活。 相似文献
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Autophagy, a conversed response to stress, has recently been studied in human cancers. Two important autophagic genes—Beclin-1
and LC3 are reported in several human cancers. However, the expressions of Beclin-1 and LC3 in lung cancer have not yet been
investigated. In the present study, we investigated the expression of Beclin-1 and LC3, and the relationship between the expression
profile and the clinical or pathological changes in human lung cancer. 40 primary lung cancer patients are involved in present
study. mRNA expressions of Beclin-1 and LC3-II were detected by Real Time PCR and the protein levels were assessed by immunohistochemistry
and western blot. Relative lower expressions of Beclin-1 and LC3-II mRNA were found in the lung cancer tissues compared to
counterpart normal tissues. Consistently, the lower amount of Beclin-1 and LC3-II protein was found in lung cancer tissues.
However, the expressions of Beclin-1 and LC3-II in lung cancer tissues were not affected by patients’ age, gender, smoking,
histological type, lymph node metastasis and tumor-node-metastasis (TNM) stage. Both mRNA and protein levels of Beclin-1 and
LC3-II were significantly decreased in lung cancer tissues which suggested that autophagy may be involved in the pathogenesis
of lung cancer. 相似文献