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《生物技术通报》2020,(7)
聚羟基脂肪酸酯(PHA)是微生物细胞内合成的高分子生物聚酯,当培养基中生长所必需的营养物质含量有限,而碳源物质过多时,会促进PHA的积累。众多PHA产品均具有生物可降解性以及优异的物理化学特性,有望替代传统塑料从而减少"白色塑料垃圾"的产生。但是较高的生产成本限制了PHA进一步的产业化和大规模应用。利用廉价易得的原材料作为微生物的碳源制备PHA是降低生产成本的有效途径之一。废弃油脂作为碳氢化合物,具有良好的微生物利用潜力。目前,以废油脂为原料、通过微生物合成可生物降解塑料已成为研究热点。该方法不但可以降低PHA的生产成本,解决废油脂的处理和高值化利用问题,还可以替代部分传统塑料的使用,符合我国绿色循环可持续发展的战略。文章系统总结了PHA的种类和应用,利用废弃油脂微生物合成PHA的最新进展以及微生物胞内PHA的提取方法,并对其合成PHA的有效实现和发展前景进行了展望。 相似文献
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《中国科学:生命科学》2015,(10)
合成生物学的迅猛发展使其在各个领域得到了广泛应用,底盘设计、元件组装、代谢网络的从头构建、大片段DNA克隆、多片段DNA拼接等合成生物学技术的开发和利用大大提高了工业生物技术的竞争力.聚羟基脂肪酸酯(PHA)是一种具有生物可降解和生物相容性等优良特性的生物塑料,可以在许多细菌胞内合成,已经被开发应用于多个领域.但是,PHA高昂的生产成本阻碍了其大规模应用.基于合成生物学研究而得到的新方法、新技术可以改变细菌生长模式、生长条件以及细菌形态,从而进一步降低PHA的生产成本.另一方面,通过改造细菌基因组如弱化?-氧化途径可以得到不同种类的重组菌株,用于生产具有不同性能的包括无规共聚物、嵌段共聚物、带有官能团的聚合物等在内的新型多功能PHA材料.合成生物学的应用开创了低成本、高附加值的PHA材料生产的新时代,为PHA的产业化奠定了坚实的基础. 相似文献
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聚羟基脂肪酸酯(PHA)是一类由微生物合成的高分子聚酯的统称,具有生物可降解性、生物可再生性和良好的生物相容性,应用前景广阔。PHA具有类似塑料的材料学性能,倍受到科学界和工业界的关注,但是生产成本较高等原因极大地限制了其大规模应用。本研究通过筛选优化在微氧条件下能够高效调控基因表达的启动子,能有效提高生产菌株在微氧条件下积累PHA的能力,减少生产能耗,降低成本。首先,在大肠杆菌基因表达库中筛选出5个在微氧条件下高效调控基因表达的启动子,与编码红色荧光蛋白的RFP报告基因相连,通过酶标仪检测RFP的荧光信号值,对5个不同的微氧启动子的表达强度进行评估,比较得到其中最高效的启动子Pslp。为进一步提高生产PHA的效率,将2个Pslp序列采用串联的方式构建得到一个新启动子P2slp,利用其调控PHA代谢合成途径中3个关键基因phbC、phbA和phbB的表达。通过发酵扩大生产,在启动子P2slp的调控下,重组大肠杆菌的细胞干重由22 g/L提高至29 g/L,PHA的产量由49.1%提高至81.3%。本研究通过筛选优化启动子提高了重组大肠杆菌生产PHA的产量,为PHA的产业化应用提供了一种有效的提高PHA产量的方法,具有实际价值。 相似文献
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萜类生物合成的基因操作 总被引:7,自引:0,他引:7
萜类是一组结构迥异的化合物家族,其中很多具有较大的应用价值,如青蒿素和紫杉醇等,它们在多种微生物和植物中合成,但其天然产量低。萜类代谢工程通过DNA重组技术改造萜类合成细胞中的代谢途径,以提高萜类最终产量或在不含萜类的生物中合成萜类,为促进有用萜类合成提供了新的机会。以萜类化合物生物合成途径的基因转移与表达为切入点,综述了目前在微生物及植物中应用代谢工程提高萜类产量的研究进展。 相似文献
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通过对6种藓类植物,即褶叶青藓(Brachythecium salebrosum(Web.et Mohr.)B.S.G.)、湿地匐灯藓(Plagiomnium acutum(Lindb.)Kop.)、侧枝匐灯藓(Plagiomnium maximoviczii(Lindb.)Kop.)、大凤尾藓(Fissidensnobilis Griff.)、大羽藓(Thuidium cymbifolium(Doz.et Molk.)B.S.G.)和大灰藓(Hypnum plumaeforme Wils.)嫩茎和老茎的石蜡切片和显微观察发现,同一藓类植株的嫩茎和老茎,茎结构稳定,不同种藓类植物茎横切面具有不同特征.植物体茎横切面形状、表层细胞的层数、细胞大小和细胞壁厚薄、皮层细胞大小和形状、中轴的有无以及比例等特征可以作为藓类植物的分科分类依据之一. 相似文献
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The levels of endogenous phytohormones and respiratory rate in nine sorts of flowers such as Cymbidium faberi Rolfe, Nopalxochia ackermannii Kunth and others were investigated both at full bloom and senescence and meanwhile the effect of exogenous phytohormones on prolonging the blossoms and promoting ethylene production were tested. There is a high content of endogenous ethylene in all the long-lived flowere, about 3–16 folds higer than the short-lived ones. There is a high level of ABA at full blooming flowers of short-lived flowers, in which there is no or only some cytokinins in it, but the ratio of CTK (6BA+zeatin)/ABA is smaller(l.7). The endogenous ABA reached a much higher level at senescence in all nine sorts of flowers, so it is reasonable to consider that it is ABA which plays an important role of regulation in controlling flower's senescence. There is a much higher level of GA3 and zeatin in the long-lived flowers which is not demonstrated in the shortlived ones. The respiratory rate is one of the factors controtling the longevity of flowers, but it does not play a decided role. Application of 6BA and zeatin prolongs distinctly orchid’s longevity, however exogenous IAA through the promotive action on ethylene production, evidently extends the longevity of the flowers of the Nopalxochia ackermannii Kunth. 相似文献
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龙胆科药用植物化学成分的研究现状 总被引:16,自引:0,他引:16
龙胆科植物在我国的分布范围很广,且多数为药用植物,其多数种属的药用植物,至今其化学成分尚未被系统研究。综述了目前龙胆科药用植物的化学成分的研究现状及一般提取方法,对近年来发现的环烯醚萜及裂环烯醚萜类化合物进行了总结,为本科药用植物的更深入研究提供了参考。 相似文献
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真菌类遗传学分析的知识结构教学 总被引:5,自引:2,他引:3
本文以认知结构理论为指导,讨论了真菌类遗传分析与高等动植物遗传分析的内在联系,认为利用这种内在联系进行教学可收到好的效果并说明了作者的具体教学过程。
Abstract:In the paper, the relationship between genetic analysis of Fungi and genetic analysis of high animal and plant was discussed.A good results were obtained when we adopted this method in the teaching. 相似文献
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Shinjiro Ogita Hamako Sasamoto Edward C. Yeung Trevor A. Thorpe 《In vitro cellular & developmental biology. Plant》2001,37(2):268-273
Summary Embryogenic tissues of sugi (Cryptomeria japonica) were induced on a modified Campbell and Durzan (CD) medium containing 1 μM 2,4-dichlorophenoxyacetic acid (2,4-D) and 600 mg l−1 glutamine, and subcultured in the medium of the same composition for over 1 yr. This resulted in a mixed culture of embryogenic
and non-embryogenic cells. When embryogenic cells were isolated and cultured independently, their capacity to form embryogenic
aggregates was lost. Thus, the non-embryogenic cells present within a mixed culture system were essential to the formation
of embryogenic aggregates. When embryogenic tissues were isolated and cultured independently on a high glutamine-containing
(2400 mg l−1) medium, dry weights and endogenous levels of glutamine increased, and the tissue could generate a large number of embryogenic
aggregates. Amino acid analysis of embryogenic and non-embryogenic cells from the maintenance culture indicated a higher level
of glutamine was present in the latter. The high endogenous level of glutamine in the non-embryogenic portion of mixed cell
masses may be the supplier of glutamine for maintaining the embryogenic property of the tissues. 相似文献
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E. V. Rozengart N. E. Basova A. A. Suvorov 《Journal of Evolutionary Biochemistry and Physiology》2009,45(1):27-36
The review deals with study of enzymologic properties of a novel highly specific acetylcholinesterase substrate, N-(β-acetoxyethyl) piperidinium iodomethylate (“piperidylcholine”), and its 30 derivatives that were tested as effectors of cholinesterases of mammals and various species of Pacific squids. It was proven for the first time that responsible for specificity of action was structure of cyclic ammonium grouping of the alcohol part of molecule of the ester substrate. Analysis of specificity is performed based on enzymatic hydrolysis parameters—activity of catalytic center of cholinesterases and bimolecular constant of the reaction rate that are determined at optimal and low substrate concentrations. Among the specially synthesized group of thioester compounds there is revealed one more highly specific acetylcholinesterase substrate—N-(β-acetoxyethyl) piperidinium. 相似文献
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Seed germination of an aurea mutant of tomato ( Lycopersicon esculentum Mill.) is promoted by continuous irradiation with red, far-red or long-wavelength far-red (758 nm) light as well as by cyclic irradiations (5 min red or 5 min far-red/25 min darkness). Far-red light applied immediately after each red does not change the germination behaviour. Seed germination of the isogenic wild-type, cv. UC-105, is promoted by continuous and cyclic red light while it is inhibited by continuous and cyclic far-red light and by continious 758 nm irradiation. Far-red irradiation reverses almost completely the promoting effect of red light. The promoting effect (in the aurea mutant) and the inhibitory effect (in the wild-type) of continuous far-red light do not show photon fluence rate dependency above 20 nmol m−2 s−1 . It is concluded that phytochrome controls tomato seed germination throgh low energy responses in both the wild type and the au mutant. The promoting effect of continuous and cyclic far-red light in the au mutant can be attributed to a greater sensitivity to Pfr . 相似文献
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目的 针对医疗机构的合理用药水平进行评价研究。方法 根据医疗机构合理用药的具体要求,构建医疗机构合理用药评价指标体系,采用基于模糊群决策的方法和多指标评价分析法构建医疗机构合理用药评价模型。结果 构建了基于模糊群决策的医疗机构合理用药评价模型,并通过实例分析证明了评价模型的可行性。结论 建立的基于模糊群决策的医疗机构合理用药评价模型能够对医疗机构的合理用药水平进行科学评价,为提高医疗机构合理用药水平奠定基础。 相似文献