合成生物学与代谢工程在谷氨酸棒杆菌产氨基酸中的应用

氨基酸是重要的化合物,在食品、医药、化工等领域具有广泛用途.多种氨基酸可以通过蛋白质水解提取法、化学合成法以及微生物法生产,现如今大部分的氨基酸都开始尝试微生物发酵法实现工业生产.谷氨酸棒杆菌(Corynebacterium glutamicum)作为发酵生产氨基酸的先驱者,其生产的氨基酸产量已达年产数百万吨.随着合成生物学技术以及新一代基因编辑技术的兴起,谷氨酸棒杆菌能生产的氨基酸种类从传统的几种氨基酸扩大到了几乎所有氨基酸及其衍生物.本文综述了近年来利用代谢工程及合成生物学工具对谷氨酸棒杆菌的改造技术,并介绍了一些利用谷氨酸棒杆菌生产传统氨基酸以及非天然氨基酸的典型案例,为谷氨酸棒杆菌突破所有氨基酸生产瓶颈提供参考.     

氨基酸生产与应用进展

<正> 目录一、序二、氨基酸的生产技术(一)发酵法(二)化学合成法(三)酶与化学—酶法(四)蛋白质水解物提取法三、氨基酸在各个工业领域中的应用     

由天然蛋白质提取L-氨基酸的若干问题讨论

<正> 本文认为由天然蛋白质水解提取L-氨基酸具有设备简单、上马快、投资省、技术与设备通用性强的优点,在某些氨基酸生产中仍具有相当的竞争能力。提取法生产L-氨基酸对天然蛋白质原料应有选择。除来源可靠、廉价易得的经济因素外,还应考虑其氨基酸的结构因素与分离的技术因素。水解时不宜简单地采用双缩脲反应转阴作为终点的控制指标,应根据     

氨基酸生产新技术的发展—发酵法

<正> 一、发酵法氨基酸的生产技术,有蛋白质水解液提取法、化学合成法和发酵法,它们各有特色。在含有碳源、氮源以及盐类等单纯培养基中,微生物几乎能生成所有的氨基酸。但是,微生物具有严密的调节机制,它只高效率生成对自己生存所必须的量而从不过量。因此,要想使氨基酸发酵生产成为可能,就必须解除微生物的这一调节机制,譬如在一特殊环境下培养微生物     

氨基酸生产和海洋生物的氨基酸资源开发

氨基酸在医药、食品、饲料等领域有着极为重要和广泛的用途,世界上氨基酸总需求量以５～１０％递增,市场竞争十分激烈。生物资源提取、化学合成、生物合成和综合法是生产氨基酸的４种技术,目前的发展趋势为生物合成和综合法,特别是将现代生物工程技术应用于氨基酸生产。另外,氨基酸生产领域另一个新的倾向是海洋生物氨基酸资源的开发和应用,尤其是海洋生物所产生的特殊氨基酸、肽及其衍生物的开发,同时,综合利用海产品加工后的废弃物来生产氨基酸也受到重视。     

茶叶中氨基酸的提取方法研究

比较了沸水、0.1 mol·L-1盐酸、甲醇、无水乙醇、85％乙醇、60％乙醇等不同溶剂提取茶叶中氨基酸的效果,结果以60％乙醇超声波法提取60 min最好;比较了用6 mol·L-1盐酸采用电磁水解法和超声波法提取茶叶中氨基酸的效果,电磁水解法优于超声波法,但电磁水解法对含硫氨基酸破坏较大.     

发酵法生产β-胡萝卜素菌丝体中氨基酸含量的分析

采用日立８３５－５０型氨基酸分析仪,测定了发醇法生产的β－胡萝卜素菌丝体及提取β－胡萝卜素后剩余的菌渣中氨基酸含量,结果表明：在氨基酸总含量中,必需氨基酸含量较高;在β－胡萝卜素菌丝体、菌渣中,赖氨酸含量较高,谷氨酸含量最高。     

第三届全国氨基酸研究开发暨综合应用新技术、新设备交流研讨会在上海召开

<正>为推动氨基酸行业的可持续发展,拓宽氨基酸的应用领域,交流展示氨基酸行业的开发、生产和应用等核心技术,中国高科技产业化研究会于2012年5月25日-27日在上海召开"全国氨基酸研究开发与综合应用新技术、新设备交流研讨会"。会议邀请了相关研究机构、大学及产业领域的专家作专题报告,就氨基酸的现状与发展趋势、生产(提取)工艺技术、检测方法和应用技术等内容开展了交流。其中主要学术报告有:     

活性炭色谱法分离苯丙氨酸、酪氨酸

根据活性炭对苯丙氨酸、酪氨酸的选择性吸附特性和二者在活性炭吸附中的差异,通过活性炭吸附与氨水、乙醇二步解吸的活性炭色谱法从多种氨基酸的猪血粉水解液、棉籽蛋白水解液中成功地分离提取了苯丙氨酸、酪氨酸。活性炭色谱法工艺对提取法、发酵法生产苯丙氨酸具有实用价值。还为联合离子交换色谱法分离水解液中其他氨基酸改善了物料条件,从而较好地解决了树脂毒化问题、氨基酸交叉重选问题,并使洗脱溶液中杂质少、纯度高,易于结晶。     

制革废弃物中氨基酸的提取和分离

综述了制革废弃物中氨基酸的提取及分离技术的发展状况 ,包括如何从制革厂回收的毛中提取胱氨酸等氨基酸以及如何从皮屑和铬革屑中提取脯氨酸等各种氨基酸的方法     

Curcuminoids as inhibitors of thioredoxin reductase: A receptor based pharmacophore study with distance mapping of the active site

Curcumin is the yellow pigment of turmeric that interacts irreversibly forming an adduct with thioredoxin reductase (TrxR), an enzyme responsible for redox control of cell and defence against oxidative stress. Docking at both the active sites of TrxR was performed to compare the potency of three naturally occurring curcuminoids, namely curcumin, demethoxy curcumin and bis-demethoxy curcumin. Results show that active sites of TrxR occur at the junction of E and F chains. Volume and area of both cavities is predicted. It has been concluded by distance mapping of the most active conformations that Se atom of catalytic residue SeCYS498, is at a distance of 3.56 from C13 of demethoxy curcumin at the E chain active site, whereas C13 carbon atom forms adduct with Se atom of SeCys 498. We report that at least one methoxy group in curcuminoids is necessary for interation with catalytic residues of thioredoxin. Pharmacophore of both active sites of the TrxR receptor for curcumin and demethoxy curcumin molecules has been drawn and proposed for design and synthesis of most probable potent antiproliferative synthetic drugs.     

Phylogenetic definitions and taxonomic philosophy

An examination of the post-Darwinian history of biological taxonomy reveals an implicit assumption that the definitions of taxon names consist of lists of organismal traits. That assumption represents a failure to grant the concept of evolution a central role in taxonomy, and it causes conflicts between traditional methods of defining taxon names and evolutionary concepts of taxa. Phylogenetic definitions of taxon names (de Queiroz and Gauthier 1990) grant the concept of common ancestry a central role in the definitions of taxon names and thus constitute an important step in the development of phylogenetic taxonomy. By treating phylogenetic relationships rather than organismal traits as necessary and sufficient properties, phylogenetic definitions remove conflicts between the definitions of taxon names and evolutionary concepts of taxa. The general method of definition represented by phylogenetic definitions of clade names can be applied to the names of other kinds of composite wholes, including populations and biological species. That the names of individuals (composite wholes) can be defined in terms of necessary and sufficient properties provides the foundation for a synthesis of seemingly incompatible positions held by contemporary individualists and essentialists concerning the nature of taxa and the definitions of taxon names.     

Chronological Events Associated with the Antagonistic Properties of Trichoderma harzianum against Botrytis cinerea: Indirect Evidence for Sequential Role of Antibiosis and Parasitism

Chronological events associated with the degradation of Botrytis cinerea by a strain of Trichoderma harzianum selected for superior biocontrol ability were studied using ultrastructure and cytochemical investigations in an attempt to define the relative roles of antibiosis and parasitism in the antagonistic process. The first ultrastructural changes were observed 12 h before contact between the organisms, and were characterized by punctuated invaginations of the Botrytis plasmalemma. These reactions were followed by a gradual retraction of the plasmalemma, disorganization of the cytoplasm, loss of turgor pressure and cell death within 48 h of contact between hyphae of the interacting fungi. The first evidence of penetration of B. cinerea by T. harzianum was recorded 72 h after contact. This penetration was apparently mediated by either mechanical pressure or localized wall digestion at points of entry, as there was no clear evidence of chitinolytic degradation of the B. cinerea cell wall, as determined by cytochemical labelling of chitin with a lectin-gold conjugate. However, after 10 days there was clear indication of chitin degradation, based on the random and reduced presence of gold particles over the cell wall of B. cinerea. These results suggest that the strain of T. harzianum antagonized first and foremost by antibiosis, leading to cell death, followed by degradation of the cell by means of chitinolytic enzymes. The production of antibiotics may, therefore, be more important than that of chitinolytic enzymes in conferring superior biocontrol properties to T. harzianum.     

From the creation of the Veterinary Schools to the evolution of the notion of contagion in the 19th and 20th centuries

The creation of the Veterinary Schools in the 18th century would reveal a plethora of scientists, some of whom would be the precursors of Pasteur, some rivals, others followers collaborators or friends of the Master. Among the precursors let us name Chabbert, Huzard, Girard, Delafond, Renault, Toussaint, Galtier ; among the rivals: Chauveau, Arloing, Cornevin and Thomas; among the followers, collaborators or friends of Pasteur: Bouley, at first a resolute spontaneist, then the most fervent in defense of Pasteur (President of the Academy of Medicine and of the Academy of Sciences) and Nocard, Director of the School in Alfort, an important collaborator of Pasteur. Later, there was Leclainche, who created the International Office of Epizootics, and who was President of the Academy of Sciences; Guérin, who with Calmette developed the BCG vaccination; Ramon, the father of anatoxins (vaccines against diphtheria, and tetanus, combined vaccines, adjuvants to immunity). Thus, the creation of the Veterinary Schools contributed not only to the evolution of the notion of contagion, to the amelioration of animal health and the economics of agricultural production, but also to serious advances in human care, and to the protection of public health.     

Evolution of pupation site and interspecific competitive ability in Drosophila hydei

A competition experiment conducted over a period of 50 weeks resulted in stable coexistence of Drosophila hydei and D. melanogaster. In a repeat of this experiment the results for the first 25 weeks were similar to the results of the earlier experiment, but after this time the state of coexistence collapsed and a fairly rapid trend towards competitive exclusion was observed. Extinctions of D. melanogaster occurred in 11 of the 12 experimental cages before termination of the experiment at 50 weeks. At about the same time as the competitive ability of D. hydei increased, an alteration in the range of pupation sites utilized by this species was noted. The change in pupation site was demonstrated to be at least partially heritable, and it appears to be responsible for D. hydei's increased competitive ability. This experiment provides an example of natural selection within a competing population acting against the stability of the overall two-species system.     

Échinodermes de l'Ordovicien supérieur (Ashgill) de Sardaigne et d'Algérie

Research on the influence of sea level variations on the benthic faunas have been carried out in the Upper Ordovician of Sardinia. Study of the depositional facies and sequence analysis of the upper part (Lower Ashgill) of the Portixeddu Formation led to the identification of the sedimentary environments. Cystoids and crinoids are associated to bryozoans and brachiopods in most levels. The numerical analysis of associations and megaguilds shows that crinoids and cystoids have a higher frequency in the proximal and median facies of the upper offshore. The columnal association characterized by Conspectocrinus celticus and the coronoid Mespilocystites tregarvanicus has been discovered in the upper part of the formation. This material and complementary samples from Upper Ordovician of Sardinia and Kabylia (Algeria) bring additional data on the systematic and show the wide distribution of this fauna outside of the Ibero-armorican domain. The distribution of this echinoderm association supports a palaeogeographical position of the Ibero-armorican domain and Sardinia within the north gondwanan margin during the Lower Palaeozoic.     

Chromatic adaptation in a mutant of Fremyella diplosiphon incapable of phycoerythrin synthesis

A mutant of the chromatically adapting cyanobacterium Fremyella diplosiphon, incapable of phycoerythrin synthesis but responding to wavelength modulation of its biliprotein content, was isolated. The biliprotein composition of the mutant and of the wild type were identical after growth in red light, but green light induced, in the mutant, the synthesis of a biliviolin-type chromophore bound to some of the alpha subunits of its phycocyanin. Implications of the results on the regulation and possible pathways of biliprotein biosynthesis are discussed.     

Crystallographic orientations of structural elements in skeletons of Syringoporicae (tabulate corals,Carboniferous): implications for biomineralization processes in Palaeozoic corals

The crystallographic orientation of structural elements in skeletons of representatives of Carboniferous Syringoporicae (Auloporida) has been analysed by scanning electron microscopy (SEM), petrographic microscopy and electron backscatter diffraction (EBSD) on specimens from the Iberian Peninsula. The skeletons of the tabulate corals of the Syringoporicae consist of biogenic calcite crystals, and their microstructure is composed of lamellae, fibres and granules, or of a combination of these. Independent of the microstructure, the c‐axis is oriented towards the lumen, quasi‐perpendicular to the growth direction of the skeleton (perpendicular to the morphological axis lamellae, parallel to fibres). Most phaceloid taxa have a turbostratic distribution, as a biogenic response to prevent the cleavage of crystals. Cerioid and some phaceloid corals, whose microstructure is conditioned by wall elements, do not exhibit turbostratic distribution. Wall elements are determined by the biology of each taxon. Holacanth septal spines are composed of fibres arranged in a cone‐shape structure, sometimes clamped to the external part of the corallite and show a complex crystallography. Monacanth septal spines are spindle shaped and composed of bundles of fibres. Tabulae are composed of lamellae. Their development and crystallographic orientation depends on the position of the epithelium in each case. Shared walls are formed by a combination of the walls of two independent corallites with a median lamina, composed of granules; these have a crystallographic orientation between that of the two corallites. The growth of the microstructure is derived by a coordinated stepping mode of growth, similar to other groups of organisms such as molluscs and scleractinians. The nucleation and formation of packages of co‐oriented microcrystals suggest a growth mode similar to mineral bridges with a competitive growth mode between each crystal. The growth pattern of corallites suggests that the growth direction is divided into two main components: a horizontal growth direction towards the lumen and a vertical direction towards the top.     

Morphology of the regiones ethmoidalis and orbitotemporalis in Galea musteloides Meyen 1832 and Kerodon rupestris (Wied-Neuwied 1820) (Rodentia: Caviidae) with comments on the phylogenetic systematics of the Caviidae

The present study describes the fetal regions ethmoidalis and orbitotemporalis of the cranium of Galea musteloides and Kerodon rupestris and compares them with Galea spixii and Cavia porcellus . The fetal crania of these representatives of the Caviinae were serially sectioned and 3D plate reconstructions were built. For a broader scope, serially sectioned heads of the caviomorph taxa Hydrochaeris hydrochaeris and Dasyprocta leporina were also examined. The ethmoidal and orbitotemporal regions of the cranium provides characters that are pertinent to the discussion of systematics of the Caviinae. Nine cranial characters were identified as being significant and discussed phylogenetically. Taking the monophyly of the Cavioidea as given, two characters are autapomorphic for the genus Galea: the reduction of the crista semicircularis and the lacrimale forming the 'arco antorbitario' (Kraglievich 1930). Cavia is the sister group of Galea; synapomorphic characters are the extent of the processus palatinus medialis of the praemaxillare and the presence lamina pterygoidea of the alisphenoid. There were no apomorphic characters of the structural complexes examined that could support the Caviinae. The reduced and nonperforated alisphenoid is an autapomorphic feature of the Caviidae. The division of the nasoturbinale is evidence for a sistergroup relationship of the Hydrochaeridae and the Caviidae. Autapomorphic characters for the Cavioidea include the ventrolateral opening of the organon vomeronasale and the lateral prolongation of the lacrimale.     

Le passage vers l’Atlantique : le processus de néolithisation en Algarve (sud du Portugal)

The late beginning of the research on the neolithisation in the Algarve (southern Portugal) has been providing, as a paradox, excellent conditions for the establishment of interdisciplinary research and the test of working hypotheses. The systematic projects put forward by the University of Algarve permit us today to conclude on a preliminary basis for the formation of a Neolithic enclave at ca. 5500 cal BC, centred in the coastal territories of the region. This enclave is fully Neolithic in economic terms and it is the westernmost extension of the Mediterranean Cardial. However, some specific features of these first Neolithic groups’ artefactual items (such as pottery morphology and style and some technological aspects of chipped stone production) indicate the existence of phenomena of partial reformulation of their material cultures. According to the presently available data, this complex process seems to have occurred in similar traits also in Andalucia and coastal Morocco, that is, at the moment of the passage to the Atlantic. This individualization within the Neolithic of Cardial tradition is the equivalent to the same general cultural phenomena that have been responsible for the formation, for example, of the so-called “Franco-Iberian Cardial” or “Tirrenic Cardial” at the time of settling of the Neolithic groups in these regions.