微藻高油脂化基因工程研究策略

石化能源危机与全球气候变化已成为人类的两大重要难题。生物柴油作为可替代普通柴油的环境友好且可再生的能源受到普遍关注。相比植物油和动物脂肪生产,藻类油脂产率高且容易培养,被认为是未来生物柴油发展的重要原料之一。通过转基因技术强化油脂代谢途径,提高富油微藻含油量,已经成为新的研究热点。已有植物研究表明,增强甘油酯酰基转移酶表达,可以提高Kennedy途径代谢中间体通量,从而增加甘油三酯(TAG)的积累。本文综述了微藻油脂代谢途径的国内外研究现状和提高油脂积累的代谢调控策略;详细阐述了基于植物油脂合成强化的成功经验,通过增强微藻Kennedy途径对提高TAG生物合成的重要作用;讨论了当前转基因微藻的遗传转化方法及其需要解决的关键性科学技术问题;分析了基因工程技术调控微藻脂类代谢途径生产高油脂的可能性,并对该研究的发展进行了展望。     

元素与代谢调控

机体内进行的一切化学和物理变化都属于代谢范畴。细胞间信息和基因信息传递是代谢调控的一部分。信息传递的神经途径有赖于神经递质。神经递质的合成需要微量元素及常量元素。信息传递的液递途径有赖于激素和元素,而且激素与元素关系密切。基因传递与调控可能同锌等多种元素有关。锌指蛋白是重要和典型的基因调控蛋白。     

一种全自动微藻分析仪

本发明涉及海洋浮游植物检测的技术领域，是一种基于双特异分子探针分析方法的全自动生化分析仪，包括采样预处理模块，裂解破碎模块，探针液槽模块，升降盘模块，恒温模块，单、多吸液头模块，定量移液和加液模块，恒温震荡模块，洗板模块，酶标模块，三维机械手，气、液控制系统，电器控制系统等装置。本发明的优点是可以全自动的流程，实现近海水域的表、中、深三层水样的藻类检测与分析，可以并行测定多达20个水样，一个水样中可测定多种优势藻类的含量，克服了传统方法人力、物力上的浪费，减小了由于复杂的手工操作带来的人为误差，提高了检测的速度和精度。本发明不仅能船装载使用，也可置于岸上使用。     

温室气体减排与微藻生物能源的集成

微藻生物能源具有巨大的开发潜力及应用前景,但仍面临很多产业化瓶颈.本文分析了微藻生物能源技术的潜力与存在的问题,指出制约微藻生物能源技术发展的主要障碍为规模养殖,如何提高微藻生长效率、降低能耗、提高规模生产的可靠性仍是面临的艰巨任务.本文介绍了石油化工企业温室气体减排与微藻生物能源技术的集成及技术思路,构建了减排工业废气与生产微藻生物能源的循环经济模式.此外,还介绍了中国石化在利用温室气体发展微藻生物能源技术方面的实践,围绕能源微藻选育技术、光生物反应器技术、微藻生物质加工及综合利用技术展开阐述.     

生物矿化、仿生合成与形貌调控

介绍了生物矿化材料的种类、结构、特点、形貌调控原则以及基于微生物、蛋白质、多肽、氨基酸和核酸等晶体调节剂的生物矿化材料的合成,总结了近年来生物矿化和彷生合成领域的研究进展.     

天然产物生物合成:探索大自然合成次生代谢产物的奥秘

天然产物(次生代谢产物)是大自然馈赠给人类的礼物,由于其复杂的骨架结构和良好的药用价值,吸引着化学家们对其进行结构鉴定以及化学合成。尽管人们在天然产物全合成中取得了巨大的成就,但仍然面临着合成路线长、产率低、缺乏选择性等问题。大自然是最伟大的化学家,它利用酶作为催化剂,往往能够高效地合成天然产物。在基因水平上探索大自然合成复杂多样的天然产物的奥秘不仅有助于人们进一步理解和认知有机化学,还为人们开发和利用大自然高效催化化学反应的工具——酶奠定了基础。     

金属氧化物纳米材料的电化学合成与形貌调控研究进展

金属氧化物纳米材料因其丰富的形貌、独特的性能、广泛的应用成为材料合成领域研究的热点.调控金属氧化物纳米材料的形貌对于调变其性能、拓展其应用空间具有重要意义.电化学方法由于操作简单易控、方法灵活多变,因此成为调控金属氧化物形貌的常用方法.本文综述了近年来我们在金属氧化物纳米材料的电化学合成与形貌调控方面已取得的研究结果;总结了不同金属氧化物在电化学过程中晶体生长机制和形貌调控的规律,为实现功能材料的定向合成奠定了基础.     

反应条件对深黄被孢霉催化转化十六醇合成不饱和脂肪酶的影响

 研究了深黄被孢霉催化转化十六醇合成不饱和脂肪酸过程中反应条件对底物转化率及产物选择性的影响．结果表明,亚油酸的选择性随十六醇与酵母膏比例（碳氮比）的增大而升高,亚麻酸的选择性随碳氮比的增大而降低,油脂的选择性和油脂的产率随碳氮比的变化规律相似．十六醇浓度为0．5％时,油脂的选择性、产率及醇的转化率最高,亚油酸和亚麻酸的选择性也最高．油脂的选择性和产率在pH＝7时较高,而醇的转化率随pH升高而降低,亚油酸和亚麻酸的选择性在pH＝6时分别达到最大值．油脂的选择性、产率和醇的转化率在23～28℃达到较高水平,亚油酸和亚麻酸的选择性在23℃达到最大值．油酸的选择性对油脂的选择性有重要影响,二者的变化规律相似．     

微藻与塑料混合热解制备低氮低氧富烃液体油

为了减少油中氮氧化合物,提高微藻生物油品质,本研究在固定床上开展了微拟球藻(NS)和聚乙烯塑料(LDPE)的混合热解/催化特性,探讨了O和N在热解气、液、固相的分布,并以此探讨了微藻与LDPE之间的交互作用以及催化剂的加入对混合热解的影响.研究发现,混合热解能有效抑制O和N向油中转移,促进微藻中O转变为H2O,N向气体...     

超四面体硫簇结构调控与电化学发光研究进展

电化学发光(ECL)因其独特的性能特点在生物分析等领域展现出广阔的应用前景,高效ECL试剂的开发则为性能优异的传感器件的发展和临床应用提供了重要工具. 开放骨架超四面体硫簇由于同时具有分子筛的多孔结构和半导体的优异光电性能,在ECL分析中受到了越来越多的关注. 超四面体硫簇的结构组成可以实现原子级别的精确调控,并且其本身还可以作为结构单元来构筑多孔结构半导体材料. 这些特点使通过原子级别的结构组成调节来调控超四面体硫簇的性能成为可能,为发展性能优异的电化学发光材料,拓展其在生化传感、免疫分析和生物成像等方面的应用提供有效工具. 本综述总结了超四面体硫簇的合成、缺陷掺杂、功能调控及ECL生化分析等方面的研究进展,为推进高效ECL新材料的发展和新应用的拓展提供了借鉴.     

Metabolic Engineering of Microbial Cell Factories for Biosynthesis of Flavonoids: A Review

Flavonoids belong to a class of plant secondary metabolites that have a polyphenol structure. Flavonoids show extensive biological activity, such as antioxidative, anti-inflammatory, anti-mutagenic, anti-cancer, and antibacterial properties, so they are widely used in the food, pharmaceutical, and nutraceutical industries. However, traditional sources of flavonoids are no longer sufficient to meet current demands. In recent years, with the clarification of the biosynthetic pathway of flavonoids and the development of synthetic biology, it has become possible to use synthetic metabolic engineering methods with microorganisms as hosts to produce flavonoids. This article mainly reviews the biosynthetic pathways of flavonoids and the development of microbial expression systems for the production of flavonoids in order to provide a useful reference for further research on synthetic metabolic engineering of flavonoids. Meanwhile, the application of co-culture systems in the biosynthesis of flavonoids is emphasized in this review.     

Highly Valuable Polyunsaturated Fatty Acids from Microalgae: Strategies to Improve Their Yields and Their Potential Exploitation in Aquaculture

Microalgae have a great potential for the production of healthy food and feed supplements. Their ability to convert carbon into high-value compounds and to be cultured in large scale without interfering with crop cultivation makes these photosynthetic microorganisms promising for the sustainable production of lipids. In particular, microalgae represent an alternative source of polyunsaturated fatty acids (PUFAs), whose consumption is related to various health benefits for humans and animals. In recent years, several strategies to improve PUFAs’ production in microalgae have been investigated. Such strategies include selecting the best performing species and strains and the optimization of culturing conditions, with special emphasis on the different cultivation systems and the effect of different abiotic factors on PUFAs’ accumulation in microalgae. Moreover, developments and results obtained through the most modern genetic and metabolic engineering techniques are described, focusing on the strategies that lead to an increased lipid production or an altered PUFAs’ profile. Additionally, we provide an overview of biotechnological applications of PUFAs derived from microalgae as safe and sustainable organisms, such as aquafeed and food ingredients, and of the main techniques (and their related issues) for PUFAs’ extraction and purification from microalgal biomass.     

An Unusual Type II Polyketide Synthase System Involved in Cinnamoyl Lipid Biosynthesis

As a unique structural moiety in natural products, cinnamoyl lipids (CLs), are proposed to be assembled by unusual type II polyketide synthases (PKSs). Herein, we demonstrate that the assembly of the CL compounds youssoufenes is accomplished by a PKS system that uniquely harbors three phylogenetically different ketosynthase/chain length factor (KS/CLF) complexes (YsfB/C, YsfD/E, and YsfJ/K). Through in vivo gene inactivation and in vitro reconstitution, as well as an intracellular tagged carrier‐protein tracking (ITCT) strategy developed in this study, we successfully elucidated the isomerase‐dependent ACP‐tethered polyunsaturated chain elongation process. The three KS/CLFs were revealed to modularly assemble different parts of the youssoufene skeleton, during which benzene ring closure happens right after the formation of an ACP‐tethered C18 polyene. Of note, the ITCT strategy could significantly contribute to the elucidation of other carrier‐protein‐dependent biosynthetic machineries.     

高脂饮食对小鼠脂肪代谢和矿物元素代谢的影响

为探讨高脂饮食对小鼠脂肪代谢和矿物元素代谢的影响,用昆明(KM)小鼠24只,出生28 d后随机分成2组,各12只,分别给予高脂饲料与普通饲料,饲养至第9周眼球取血处死,取皮下、腹腔、肠系膜脂肪,毛,肝,血,计算体质量脂肪质量比,测定毛、肝、血中Zn、Ca、Cu、Mn、Mg、Fe含量。结果表明,高脂饮食小鼠体质量增加(P<0.05),单位腹腔脂肪及血Ch显著性增加(P<0.01)。肝Zn、Cu、Mg、Fe、Mn显著降低(P<0.01),血凝块Zn升高(P<0.05),Cu降低(P<0.05),毛Mg降低(P<0.05)。提示高脂饮食引起体质量与血脂增加,脂肪堆积,矿物元素代谢紊乱;不同器官矿物元素的代谢紊乱有差异,以肝脏最显著。     

Alteration of Lipid Membrane Rigidity by Cholesterol and Its Metabolic Precursors

Caused by biosynthesis defects, cholesterol deficiency can lead to developmental disorders and malformations, with possible implication of lipid membrane properties. We show that modification of sterol chemical structure alters membrane physical properties significantly. By X-ray diffraction and osmotic stress, we measure changes in the bending rigidity of bilayers containing either cholesterol or one of its metabolic precursors. Membrane elasticity differs dramatically between slightly different sterols and varies in the sequence lanosterol < 7-dehydrocholesterol < lathosterol < cholesterol. We interpret the results in terms of sterol location within lipid structures and modification of lateral stress, a structural feature relevant to interactions within biological membranes. We find that cholesterol is most efficient in enhancing membrane rigidity, a possible clue to why depletion or replacement with other sterols can affect cellular structures.     

Carotenoids and Their Biosynthesis in Fungi

Carotenoids represent a class of pigmented terpenoids. They are distributed in all taxonomic groups of fungi. Most of the fungal carotenoids differ in their chemical structures to those from other organisms. The general function of carotenoids in heterotrophic organisms is protection as antioxidants against reactive oxygen species generated by photosensitized reactions. Furthermore, carotenoids are metabolized to apocarotenoids by oxidative cleavage. This review presents the current knowledge on fungal-specific carotenoids, their occurrence in different taxonomic groups, and their biosynthesis and conversion into trisporic acids. The outline of the different pathways was focused on the reactions and genes involved in not only the known pathways, but also suggested the possible mechanisms of reactions, which may occur in several non-characterized pathways in different fungi. Finally, efforts and strategies for genetic engineering to enhance or establish pathways for the production of various carotenoids in carotenogenic or non-carotenogenic yeasts were highlighted, addressing the most-advanced producers of each engineered yeast, which offered the highest biotechnological potentials as production systems.     

Efficiency Assessment of Bacterial Cellulose on Lowering Lipid Levels In Vitro and Improving Lipid Metabolism In Vivo

Bacterial cellulose (BC) is well known as a high-performance dietary fiber. This study investigates the adsorption capacity of BC for cholesterol, sodium cholate, unsaturated oil, and heavy metal ions in vitro. Further, a hyperlipidemia mouse model was constructed to investigate the effects of BC on lipid metabolism, antioxidant levels, and intestinal microflora. The results showed that the maximum adsorption capacities of BC for cholesterol, sodium cholate, Pb²⁺ and Cr⁶⁺ were 11.910, 16.149, 238.337, 1.525 and 1.809 mg/g, respectively. Additionally, BC reduced the blood lipid levels, regulated the peroxide levels, and ameliorated the liver injury in hyperlipidemia mice. Analysis of the intestinal flora revealed that BC improved the bacterial community of intestinal microflora in hyperlipidemia mice. It was found that the abundance of Bacteroidetes was increased, while the abundance of Firmicutes and Proteobacteria was decreased at the phylum level. In addition, increased abundance of Lactobacillus and decreased abundance of Lachnospiraceae and Prevotellaceae were obtained at the genus level. These changes were supposed to be beneficial to the activities of intestinal microflora. To conclude, the findings prove the role of BC in improving lipid metabolism in hyperlipidemia mice and provide a theoretical basis for the utilization of BC in functional food.