利用基因工程技术提高微藻油脂含量的研究进展

利用微藻油脂制备生物柴油因具有重要的战略意义而受到世界各国的重视,成为近年来的研究热点。利用微藻制备生物柴油具有生长周期短、易于大规模培养、能大量吸收CO2及不占用耕地等优点。但是,由于对藻类油脂合成代谢中的调节机制了解不多,导致微藻基因组研究相对滞后,极大地限制了微藻生物能源的大规模开发和利用。随着现代生物技术的发展,通过基因工程、代谢工程等方法调控微藻脂类的合成代谢,提高藻类含油量和生物量已成为可能。概述了微藻中油脂的合成代谢,归纳总结利用基因工程技术提高微藻油脂含量的研究进展,为获得含油量高的工程微藻及微藻制备生物柴油提供技术储备。     

利用微藻生产可再生能源研究概况

能源是现代工业的支柱,是国民经济可持续发展的动力。生物质能源作为一种来源广泛的可再生能源,其开发利用不仅有助于缓解化石燃料日益枯竭给全球经济发展带来的危机,还可避免对环境的污染。微藻中很多种类富含油脂,可以用来生产生物柴油（脂肪酸甲酯）;另一些藻类中含有极丰富的烃类物质,化学结构与矿物油相似,提取后可加工成汽油、柴油使用;在特定条件下,绿藻和蓝藻在光合作用的同时可以产生氢气。微藻易培养,生长快,单位面积生物量大,油、烃含量高,是一类重要的生物质能源,已引起各国政府、科学家和企业家的高度关注。文中概述了利用微藻生产油脂、烃类、氢气的研究现状,探讨了利用微藻生产可再生能源存在的问题和对策,并展望了我国微藻可再生能源研究开发的发展前景。     

植物激素调控微藻储能物质积累研究进展

微藻储能物质(碳水化合物、脂类等)可以作为生物燃料和生物基化学品的可再生原料。非生物胁迫(高光强、高盐度、营养盐限制、重金属等)传统诱导微藻储能物质积累的方法影响微藻的生长,从而限制了储能物质的高效积累。植物激素作为化学信使协调植物细胞活动的一类小分子物质,可对微藻的生理代谢活动产生调控作用,包括促进微藻细胞分裂,增加胁迫耐受,提高光合作用效率,从而提高藻类生物量,增加油脂、叶绿素和蛋白质含量。本文中,笔者概述了近年来国内外利用外源添加植物激素结合非生物胁迫条件调控微藻储能物质积累的研究进展,探讨了植物激素对微藻储能物质积累的作用机制,并提出未来可能的研究方向。     

固碳产油微藻的基因工程改造

藻种的选育和基因工程改造是微藻生物柴油研究的核心。为此,简要综述了微藻从光合作用到甘油三酯(TAG)合成过程中的关键基因及其代谢调控等方面的研究进展。从光合作用固碳、中心碳代谢、脂肪酸合成、TAG的组装、抑制TAG合成的竞争途径及脂类的分解途径等几个方面入手,浅析各个代谢途径中关键基因的作用及其表达调控。在此基础上,探讨微藻基因工程改造的可行性并指出微藻生物柴油在生物质能源领域中的前景及其综合利用的发展优势。     

经济微藻高密度培养技术及其生物资源化利用

经济微藻富含不饱和脂肪酸、蛋白质、碳水化合物等多种生物活性物质, 可以应用于食品加工业、水产养殖业、医药与美容业、废水处理环保业和生物能源业等各行业。开发和利用微藻生物资源将是解决人类能源需求的重要途径, 微藻产业化的发展进程与社会经济、生态环境和人类健康有密切的关系。微藻高密度培养是提高微藻生物质产量和活性代谢产物, 发展生物质能源的关键环节。论文综述了微藻的社会经济价值, 指出了其在能源、食品、水产等行业的重要作用; 介绍了开放式培养和封闭式培养的两大类技术体系, 比较分析了柱状光反应器、平板光反应器和管状光反应器的特点; 概括了影响经济微藻生长和油脂含量的主要因素, 包括光照、温度、pH、营养元素等, 最后展望了经济微藻培养及其生物资源化利用的前景。     

微藻三酰甘油合成途径及其最新研究进展

三酰甘油(triacylglycerols,TAGs)是动物、植物、微生物和微藻细胞主要的储藏性脂类,它可应用于食品、轻工业和生物燃料等方面,是一种新型可再生能源——生物柴油生产的重要原料。与高等油料作物相比,微藻具有光合作用效率高、生长速度快、油脂产量高、不占用农业耕地和适应多种生长环境等优势,是一种潜在的新型生物柴油生产原料。然而,目前人们对有机体,尤其是微藻细胞内TAG合成与积累的分子机制及细胞的代谢调控机制还知之甚少。对TAG合成的一系列重要过程,包括脂肪酸的合成,TAG生物合成的主要途径和旁路途径,以及与TAG合成相关的关键酶和重要基因等进行了综述,特别对微藻细胞中与TAG合成相关的关键基因的最新研究进展进行了总结,旨在更好地了解油脂代谢的调控途径,为最大限度地供应生物柴油的生产原料提供理论基础。     

微藻减排CO2制备生物柴油的研究进展

碳减排与可再生能源的开发利用是研究可持续发展的热点,而微藻在此方面具有巨大优势.利用微藻减排CO2合成生物柴油生产原料油脂,对于解决能源短缺和全球变暖具有重大战略意义.将碳减排与微藻生物柴油的制备方法相结合,对微藻转化CO2合成生物油脂的机制,微藻油脂积累的影响因素以及国内外在工业上的研究概况等方面进行综合归纳和评述,并对微藻生物油脂的发展前景进行了展望.     

用于生物柴油的产油微藻研究进展

在新能源开发过程中,人们注意到利用微藻生产可再生能源.微藻具有光能自养能力,在吸收储存太阳能的同时,还能固定CO2、减轻温室效应.相比于陆生植物,微藻具有生长快、光合作用效率高、节省土地、可以工业化生产等优点.一些微藻在一定的条件下可以以积累油脂的方式贮存太阳能,人们可以利用油脂来生产生物柴油.目前微藻油脂的产量还较低,成本较高,用微藻油脂生产生物柴油还不具有竞争力.要使微藻油脂生物柴油具有现实意义,必须保证微藻高效率、低成本生产油脂.     

LED光质调控微藻生长及目标产物积累的研究进展

光是影响微藻光自养生长的最重要因素.LED光质在调控微藻生长及目标产物积累方面的巨大优势已经引起了诸多研究者及相关企业的高度重视.基于LED光质调控技术开发的微藻培养工艺有望革新现有生产技术,促进微藻产业的快速发展.为此,本文阐述了微藻可吸收利用的光谱范围及光受体、不同LED光质对微藻生长及目标产物积累的影响、基于LE...     

微藻生物能源研究取得新进展

中国科学院青岛生物能源与过程研究所能源藻类资源团队刘天中研究员针对微藻生物柴油生产成本和能耗影响大的微藻油脂提取、微藻生物柴油转化等下游关键技术进行了系列研究,结果发表在《Biore-sourceTechnology》杂志上。     

Scurvy in capybaras bred in captivity in Argentine

In order to determine if the absence of vitamin C in the diet of capybaras (Hydrochoerus hydrochaeris) causes scurvy, a group of seven young individuals were fed food pellets without ascorbic acid, while another group of eight individuals received the same food with 1 g of ascorbic acid per animal per day. Animals in the first group developed signs of scurvy-like gingivitis, breaking of the incisors and death of one animal. Clinical signs appeared between 25 and 104 days from the beginning of the trial in all individuals. Growth rates of individuals deprived of vitamin C was considerably less than those observed in the control group. Deficiency of ascorbic acid had a severe effect on reproduction of another population of captive capybaras. We found that the decrease in ascorbic acid content in the diet affected pregnancy, especially during the first stages. The results obtained suggest that it is necessary to supply a suitable quantity of vitamin C in the diet of this species in captivity.     

Changes in lactate dehydrogenase activity in chicken tissues in hyperthyreosis in ontogenesis

The lactate dehydrogenase activity in reactions of lactate oxidation and synthesis was studied in subfractions of the chicken brain, heart and liver at the embryonal, early postembryonal and adult stages of development after thyroxine administration. It has been shown that during embryogenesis thyroxine predominantly enhanced the rate of lactate oxidation in the mitochondrial tissues. A marked increase in the lactate synthesis was found in cytoplasm of the adult chicken tissues. Specificity of enzyme activity alterations was detected in the chicken brain during ontogenesis after thyroxine administration.     

Role for dopamine in malonate-induced damage in vivo in striatum and in vitro in mesencephalic cultures

Defects in mitochondrial energy metabolism have been implicated in the pathology of several neurodegenerative disorders. In addition, the reactive metabolites generated from the metabolism and oxidation of the neurotransmitter dopamine (DA) are thought to contribute to the damage to neurons of the basal ganglia. We have previously demonstrated that infusions of the metabolic inhibitor malonate into the striata of mice or rats produce degeneration of DA nerve terminals. In the present studies, we demonstrate that an intrastriatal infusion of malonate induces a substantial increase in DA efflux in awake, behaving mice as measured by in vivo microdialysis. Furthermore, pretreatment of mice with tetrabenazine (TBZ) or the TBZ analogue Ro 4-1284 (Ro-4), compounds that reversibly inhibit the vesicular storage of DA, attenuates the malonate-induced DA efflux as well as the damage to DA nerve terminals. Consistent with these findings, the damage to both DA and GABA neurons in mesencephalic cultures by malonate exposure was attenuated by pretreatment with TBZ or Ro-4. Treatment with these compounds did not affect the formation of free radicals or the inhibition of oxidative phosphorylation resulting from malonate exposure alone. Our data suggest that DA plays an important role in the neurotoxicity produced by malonate. These findings provide direct evidence that inhibition of succinate dehydrogenase causes an increase in extracellular DA levels and indicate that bioenergetic defects may contribute to the pathogenesis of chronic neurodegenerative diseases through a mechanism involving DA.     

SSTR5 ablation in islet results in alterations in glucose homeostasis in mice

Somatostatin (SST) peptide is a potent inhibitor of insulin secretion and its effect is mediated via somatostatin receptor 5 (SSTR5) in the endocrine pancreas. To investigate the consequences of gene ablation of SSTR5 in the mouse pancreas, we have generated a mouse model in which the SSTR5 gene was specifically knocked down in the pancreatic beta cells (betaSSTR5Kd) using the Cre-lox system. Immunohistochemistry analysis showed that SSTR5 gene expression was absent in beta cells at three months of age. At the time of gene ablation, betaSSTR5Kd mice demonstrated glucose intolerance with lack of insulin response and significantly reduced serum insulin levels. Insulin tolerance test demonstrated a significant increase of insulin clearance in vivo at the same age. In vitro studies demonstrated an absence of response to SST-28 stimulation in the betaSSTR5Kd mouse islet, which was associated with a significantly reduced SST expression level in betaSSTR5Kd mice pancreata. In addition, betaSSTR5Kd mice had significantly reduced serum glucose levels and increased serum insulin levels at 12 months of age. Glucose tolerance test at an older age also indicated a persistently higher insulin level in betaSSTR5Kd mice. Further studies of betaSSTR5Kd mice had revealed elevated serum C-peptide levels at both 3 and 12 months of age, suggesting that these mice are capable of producing and releasing insulin to the periphery. These results support the hypothesis that SSTR5 plays a pivotal role in the regulation of insulin secretion in the mouse pancreas.