世界赖氨酸生产快速发展

养殖业的发展带动了赖氨酸需求的不断增长 ,国际和国内赖氨酸市场竞争也越来越激烈。本文从生产与消费双增长 ;价格波动幅度巨大 ;技术水平提高、产品出现多样化 ;以及生产多极化、市场竞争激烈等几个方面介绍了世界赖氨酸的发展趋势。我国将从赖氨酸进口大国发展成为供应大国 ,并成为国际赖氨酸市场上的中坚力量     

发酵法生产L—赖氨酸

介绍了世界上Ｌ－赖氨酸的研究概况。目前，Ｌ－赖氨酸的生产主要包括直接发酵法和酶法等。最常用的直接发地就是用某些筛选菌进行发酵，从培养液中提取所需的Ｌ－赖氨酸。     

赖氨酸的生产及发展建议

简要介绍了赖氨酸的用途、生产状况、生产方法，并提出我国发展赖氨酸的建议。     

赖氨酸的生产现状与市场前景

该文介绍了赖氨酸的生产现状、用途和急需解决的问题。随着我国饲料工业的进一步发展，即使是“复关”后，赖氨酸的市场前景依然乐观。     

L—赖氨酸的生产技术及市场分析

对赖氨酸的几种生产技术进行了评价；分析并预测了L-赖氨酸的市场前景；对我国赖氨生产提出了一些建议。     

我国赖氨酸工业技术新进展

系统介绍了我国赖氨酸工业生产技术的发展、赖氨酸生产菌种的最新研究进展以及生产过程中的发酵、提取、浓缩、结晶、干燥等操作所采用的最新技术和设备。离子交换法是从发酵液中提取赖氨酸的常用方法 ,文中简要介绍了连续离子交换系统 (ISEP)对提高赖氨酸回收率、降低能耗和减少污水排放量的作用及其应用。     

国产L—赖氨酸寻求新用途

我国饲料级赖氨酸的生产还不能满足饲料生产的需要,大部分产品需从国外进口。2000年国内L-赖氨酸需求量约为7万t,而产量不足2万t。大量的低价进口产品导致国内饲用赖氨酸市场几近饱和。作者指出,国内企业应把重点放在开发赖氨酸的其他用途上,例如,挖掘赖氨酸的医用价值。目前已有3种L-赖氨酸及其复配药获得国家药监局批准使用。     

N6-三氟乙酰基-L-赖氨酸的合成

对三氟乙酰赖氨酸的合成工艺进行了研究。三氟乙酸与乙醇在浓硫酸作用下酯化形成三氟乙酸乙酯,然后与L-赖氨酸经酰化反应得到三氟乙酰赖氨酸。酰化反应的优化条件为:pH值为11~13,反应温度-5~5℃,反应时间2h,酰化收率91.8%,HPLC分析含量达95.8%。     

赖氨酸生产与应用发展概况

目前 ,我国的赖氨酸生产能力超过 10万t/a,实际生产量只有 3万t/a。主要原因是我国的赖氨酸生产不稳定 ,产品成本高 ,品种单一 ,使得进口产品不断冲击国内市场 ,以致于国内现有的生产装置不能满负荷运转。近几年 ,国内赖氨酸新建和扩建装置不断增多 ,但进口产品量也不断增加 ,这一点非常值得注意。     

赖氨酸间歇发酵过程的计算机模拟

在赖氨酸发酵动力学方程的基础上,本文对赖氨酸发酵过程的几种主要工艺进行了计算机模拟。另外,本文还对赖氨酸发酵过程进行了最优化分析,为充分利用(?)株的优良性能,提高赖氨酸产率,提供了理论依据。     

Microbial production of L-lysine

The production of lysine by fermentation was studied, using a homoserine-deficient and aminoethylcysteine-resistant strain of Corynebacterium glutamicum, in 1-dm³ shake flasks and a 14-dm³ laboratory fermentor. Molasses was used as substrate. Superphosphate-treated black strap molasses gave better lysine production. Lysine production, residual sugar and dry cell mass were measured as a function of fermentation time. It was observed that 1 g of cell mass produced 3.36 g of lysine.     

赖氨酸生产硫酸铵废水结晶换热器腐蚀的解决

针对赖氨酸生产的含硫酸铵废水浓缩液中含有高含量氯化物对316L不锈钢换热器列管腐蚀的现象,分析了发生腐蚀的原因.通过减少氯化物的添加量等优化赖氨酸生产工艺,氯化物的质量分数由原来的4％ ～6％降低到至0.6％～0.8％;采用钛材作为换热器的换热管,解决了硫酸铵废水浓缩液结晶换热器腐蚀的问题,同时减少了废液的排放,提高了...     

Combined Hybridization and Evaluation of High-Lysine Rice: Nutritional and Physicochemical Qualities and Field Performance

Rice, as a major food crop, provides necessary energy and nutrition for humans and livestock. However, its nutritional value is affected by lysine. Using point mutation, we previously obtained AK2 (aspartokinase) and DHDPS1 (dihydrodipicolinate synthase) genes insensitive to lysine feedback inhibition and constructed transgenic lines AK2-52 and DHDPS1-22, which show increased lysine synthesis, as well as Ri-12, which shows decreased lysine degradation by inhibiting rice lysine ketoglutarate reductase/saccharopine dehydrogenase (LKR/SDH) activity. In this study, further transgenic lines were hybridized and evaluated. The lysine content of mature seeds from pyramid lines PRD and PRA increased 32.5- and 29.8-fold, respectively, compared with the wild-type, while the three-gene pyramiding line PRDA had a moderate lysine content. The total lysine, total free lysine, and total protein contents of PRD and PRA also increased and had no obvious impact on the physical and chemical quality, seed appearance, and main agronomic traits. Meanwhile, comparative analysis with polygenic polymeric lines GR containing bacterial AK (lysC) and DHDPS (dapA) genes revealed differences in the way bacterial and endogenous rice AK and DHDPS regulate lysine biosynthesis. These results provide a reference for further evaluation and commercialization of high-lysine transgenic rice.     

Production of active recombinant eIF5A: reconstitution in E.coli of eukaryotic hypusine modification of eIF5A by its coexpression with modifying enzymes

Eukaryotic translation initiation factor 5A (eIF5A) is the only cellular protein that contains the polyamine-modified lysine, hypusine [N(ε)-(4-amino-2-hydroxybutyl)lysine]. Hypusine occurs only in eukaryotes and certain archaea, but not in eubacteria. It is formed post-translationally by two consecutive enzymatic reactions catalyzed by deoxyhypusine synthase (DHS) and deoxyhypusine hydroxylase (DOHH). Hypusine modification is essential for the activity of eIF5A and for eukaryotic cell proliferation. eIF5A binds to the ribosome and stimulates translation in a hypusine-dependent manner, but its mode of action in translation is not well understood. Since quantities of highly pure hypusine-modified eIF5A is desired for structural studies as well as for determination of its binding sites on the ribosome, we have used a polycistronic vector, pST39, to express eIF5A alone, or to co-express human eIF5A-1 with DHS or with both DHS and DOHH in Escherichia coli cells, to engineer recombinant proteins, unmodified eIF5A, deoxyhypusine- or hypusine-modified eIF5A. We have accomplished production of three different forms of recombinant eIF5A in high quantity and purity. The recombinant hypusine-modified eIF5A was as active in methionyl-puromycin synthesis as the native, eIF5A (hypusine form) purified from mammalian tissue. The recombinant eIF5A proteins will be useful tools in future structure/function and the mechanism studies in translation.     

Optimization of Lysine Adsorption Process Using Strong Cation-Exchange Resin

Abstract

A simplified method is proposed for determining the optimum conditions of multicolumn adsorption of lysine from a lysine fermentation broth, in which the resin columns periodically move countercurrent to a continuous broth flow. Experimental data on dynamic isotherms in the fixed-bed column are required for the calculations. The recurrence equation involved was solved on a personal computer. Based on this model, the optimum operation conditions of lysine adsorption were determined in order to minimize the production cost of lysine recovery from lysine fermentation broth.     

中后期不同溶氧水平对赖氨酸发酵的影响

发酵过程中合理且充分供氧是提高L-赖氨酸发酵产量的主要途径之一,实际生产中溶氧控制策略又往往难以进行具体化操作,尤其是发酵中后期的溶氧水平直接决定了发酵生产的水平.通过5 L发酵罐实验分析中后期溶氧水平对赖氨酸发酵的影响,研究了不同溶氧水平条件下的发酵规律.实验数据表明,赖氨酸发酵中后期溶氧水平控制在60%~80%内,可以明显提高发酵的终点酸、转化率、酸固比和单罐总酸等生产指标,与正常控制水平(40%~60%)相比,依次分别提高了7.30%、3.08%、0.92%、5.48%.     

典型有机氮化物对饮用水消毒卤乙腈生成量和耗氯量的影响

以滤后水为本底,研究了其在氯化消毒过程中卤乙腈（HANs）的生成量,并考察了投氯量和pH值的影响。以甘氨酸、半胱氨酸、赖氨酸、亮氨酸、天门冬氨酸和甲胺6种物质为典型有机氮化物,研究了其对饮用水消毒过程中HANs生成量和耗氯量的影响。结果显示,HANs生成量与投氯量成正比、与pH值成反比。UFC结果显示滤后水本底HANs生感量为11．2μg·L^-1;有机氮化物的存在会强化消毒过程中HANs的生成,强化作用与有机氮化物性质和含量有关;6种有机氮化物对HANs的影响顺序为天门冬氨酸（36．0μg·L^-1）〉甘氨酸（17．2μg·L^-1）≈甲胺（17．0μg·L^-1）〉赖氨酸（14．0μg·L^-1）≈亮氨酸（13．8μg·L^-1）≈半胱氨酸（13．6μg·L^-1）;有机氮化物还能使耗氯量增加,增加值与有机氮化物性质和含量有关,多数有机氮化物所造成的耗氯量增加与其含量线性相关。