氨基酸生产技术讲座

八、L-谷氨酰胺、N-乙酰-L-谷氨酰胺、L-脯氨酸发酵L-谷氨酰胺、N-乙酰-L-谷氨酰胺(N-AGM)及L-脯氨酸主要用于医药。前二老为胃溃疡、十二指肠溃疡的治疗药物,后者用于配制氨基酸输液等。早在七十年代初,角田、宫井就分别报道了在L-谷氨酸发酵中有副产物L-谷氨酰胺和N-乙酰-L-谷氨酰胺的生成。大嵨等也证实在谷氨酸棒杆菌的L-谷氨酸发酵液中存在L-谷氨酰胺和N-乙酰-L-谷氨酰胺,并发现改变培养条件可使L-谷氨酰胺     

几种培养基附加物对几丁质产量的影响

试验了不同浓度的果糖、L-谷氨酰胺及N-乙酰氨基葡萄糖对黑曲霉AS18合成几丁质的影响.发现在培养基中含有3%、0.03%和0.05%的果糖、N-乙酰氨基葡萄糖和谷氨酰胺时,对黑曲霉合成几丁质有促进作用,其中前体物质N-乙酰氨基葡萄糖促进作用最为明显.在培养基中添加0.03%的N-乙酰氨基葡萄糖,几丁质产量为2.62g/L,提高了42%.     

谷氨酸生产菌的糖代谢及其调控

<正> 谷氨酸生产茵的糖代谢及其调控是一个十分活跃的研究课题. L-谷氨酸固然与我们日常生活关系密切,人们的需要量也极大,就是在生活中少为接触 L-谷氨酰胺及N-乙酰L-谷氨酰胺等作为胃溃疡、十二指肠溃疡的抗溃疡药也被大量应用着。因此,这些氨基酸(酰胺)的糖代谢很为人们所关注。本文围绕着谷氨酸生产菌的糖代谢及其调控这一中心,论述L-谷氨酸、L-脯氨酸、L-谷氨酰胺及N-乙酰L-谷氨酰胺的发     

谷氨酸发酵怎样控制碳氦比？

在谷氨酸发酵中,氮源是合成谷氨酸氨基的来源,所以谷氨酸发酵所用的氮源数量大于其它发酵用量。一般的发酵工业所用培养基碳氮比为100：0．5-2．0,而谷氨酸发酵的碳氮比为100：20～30,当碳氮比低于100：20时,菌体大量繁殖,积累少量谷氨酸,当碳氮比高于100：30时,菌体生长受到一定的抑制,产生的谷氨酸进而形成谷氨酰胺。因此在谷氨酸发酵中,     

谷氨酸发酵怎样控制碳氮比?

在谷氨酸发酵中,氮源是合成谷氨酸氨基的来源,所以谷氨酸发酵所用的氮源数量大于其它发酵用量。一般的发酵工业所用培养基碳氮比为100∶0.5~2.0,而谷氨酸发酵的碳氮比为100∶20~30,当碳氮比低于100∶20时,菌体大量繁殖,积累少量谷氨酸,当碳氮比高于100∶30时,菌体生长受到一定的抑制,产生的谷氨酸进而形成谷氨酰胺。因此在谷氨酸发酵中,     

无溶剂体系中N~α-乙酰谷氨酰甘油的酶法合成研究

研究了无溶剂体系中酶催化N-乙酰谷氨酸、甘油合成Nα-乙酰谷氨酸甘油酯的可行性。不同来源的商业酶制剂对比研究发现,固定化的Novozyme435、LipozymeRMIM、TLIM的活力明显高于游离的木瓜蛋白酶、胃蛋白酶及酰化酶及LAP15.最优酶制剂为Novo435,24h酯化率随温度提高、甘油/N-乙酰谷氨酸摩尔比增加而明显增大,酶添加量0.5%～5%范围内酯化率没有显著变化。产物中主要为1(3)-Nα-乙酰基谷氨酰-1-酰基单甘油酯,约占60%～70%,2位异构体约占20%～30%,此外有微量Nα-乙酰基谷氨酰-5-酰基单甘油酯。结果表明,生物法合成Nα-乙酰谷氨酸甘油酯是可行的。     

NCgl1221敲除和pyc过表达对谷氨酰胺发酵的影响

谷氨酰胺在生命活动中具有重要的作用,已被广泛应用于食品、医药等诸多领域。谷氨酸是谷氨酰胺生物合成的前体物质,也是谷氨酰胺生产过程中最常见的副产物。研究发现,NCgl1221基因的编码蛋白是谷氨酸分泌的重要载体,丙酮酸羧化酶是谷氨酸棒杆菌回补途径中的关键酶。为减少谷氨酰胺发酵过程中谷氨酸的积累量并提高谷氨酰胺产量,本研究利用同源重组技术敲除谷氨酰胺生产菌GM34的谷氨酸分泌载体编码基因NCgl1221,获得GM34ΔNCgl1221菌株;构建了丙酮酸羧化酶基因pyc过表达菌株GM34-pXMJ19pyc。5 L罐发酵实验表明,NCgl1221基因缺失可以使得谷氨酸积累量降低19.05%,过表达pyc基因使得谷氨酰胺产量和转化率分别提高5.54%和2.37%。可见,敲除NCgl1221、过表达pyc能够有效降低谷氨酸分泌并提高谷氨酰胺产量。     

L-谷氨酰胺对提取有什么影响?

在生产实践中,发酵液含L-谷氨酰胺0.25%时,就会明显地影响谷酸酰的提取,L-谷氨酰胺含量越高,谷氨酸结晶β-型的出现就越严重,所以应积极控制L-谷氨酰胺的生成。它来源于L-谷氨酸发酵过程,当谷氨酸形成时,在NH4+1过量情况下,及pH值低时(尤其是pH在5.5～     

谷氨酰胺酶在10 t规模酱油发酵中应用研究

鲜味是反映酿造酱油品质的一项重要指标。谷氨酰胺酶可以催化谷氨酰胺生成谷氨酸和γ-谷氨酰肽,从而提高酱油的鲜味。文章研究了在10 t规模酱油发酵过程中添加谷氨酰胺酶对酱油中谷氨酸、谷氨酰胺、γ-谷氨酰肽、氨基酸态氮和全氮等指标的影响,并对添加谷氨酰胺酶的酱油进行了HS-SPME-GC-MS分析和感官评定。结果表明,添加谷氨酰胺酶可明显提高酱油原油的谷氨酸含量、氨基酸态氮含量、全氮含量并调节γ-谷氨酰肽的种类及含量。添加谷氨酰胺酶对酱油原油的pH值和总酸含量有小幅度影响。HS-SPME-GC-MS分析表明,添加谷氨酰胺酶的酱油的挥发性风味物质发生了一定变化,醇类、醛类、酮类化合物的种类和含量都有所增加,使酱油的滋味和气味更加丰富。感官评价显示添加谷氨酰胺酶可较大幅度提升酱油的鲜味强度,小幅度减弱酱油的苦味和增加酱油的酸味,对咸味、甜味的影响较小。该研究结果为谷氨酰胺酶在酱油酿造中的应用提供了理论支持。     

大豆发酵食品与谷氨酰胺酶

谷氨酰胺酶是将L—谷氨酰胺分解的酶。而谷氨酰胺是天然蛋白质成分之一.当蛋白水解酶水解蛋白质时,可将其从肽链中解脱开来。同时谷氨酰胺是微生物在蛋白代谢过程中籍谷氨酰胺合成酶将谷氨酸合成为谷氨酰胺,因此在生物体中都会有游离谷氨酰胺存在。谷氨酰胺没有鲜味,但是谷氨酰胺酶可将其分解成具有鲜味的谷氨酸.谷氨酸的浓度愈大,味道也就愈加鲜美,所以谷氨酰胺酶在酱油、豆酱、豆豉、腐乳等大豆发酵食品的酿造过程中是一种很重要的酶。     

一种"分瓶"培养与二次接种优化谷氨酸发酵条件的方法

该试验优化了谷氨酸发酵工艺,通过谷氨酸产量的变化寻找细胞由"生长型"转入"生产型"的发酵时间,分时间段与"分瓶"培养并结合二次接种工艺发酵生产谷氨酸,取得较好的发酵结果.最终得到谷氨酸产量113g/L,糖酸转化率58%.     

味精生产中有机酸含量的抑制型离子色谱测定及焦谷氨酸产生原因分析

该研究建立了抑制型离子色谱法测定味精生产中10种有机酸的方法。对味精实际生产中不同工段样品中的有机酸含量进行测定,并进一步就味精生产中焦谷氨酸的产生原因进行初步探讨。结果表明,采用Organic acids-250/7.8有机酸柱和抑制型电导检测器,当淋洗液为1.0 mmol/L硫酸和7%乙腈、柱温为20 ℃、流速为0.3 mL/min时,能将柠檬酸、酒石酸、丙二酸、苹果酸、琥珀酸、乳酸、富马酸、甲酸、乙酸和焦谷氨酸在35 min内分离和定量。10种有机酸在对应线性范围内的线性相关系数均可达0.998以上,相对标准偏差（RSD）＜1%,回收率为92.1%～106.2%,满足实际样品的分析。焦谷氨酸产生原因分析结果表明,在谷氨酸转晶过程和味精结晶过程产生量最多,谷氨酸损失率达7.6%。该方法为味精生产中有机酸的监控和产品质量评价提供依据。     

Glutamic acid reactivity in heated protein and protein-alginate mixtures

When heated at 185°C for 35 min, only soya and gluten (out of seven proteins tested) produced measurable quantities of additional water. In the presence of 2% manucol DM (an alginate rich in mannuronic acid residues), the formation of water was markedly increased in the soya and gluten samples but not in the other proteins. Amino acid analysis showed that on heating soya in the presence of manucol DM, the glutamic acid content decreased whilst the aspartic acid content increased. When manugel GMB (an alginate rich in guluronic acid residues) was heated with soya, no loss of glutamic acid was observed and no additional water was formed. Experiments with single acids confirmed that the reaction giving rise to the formation of water primarily involved glutamic acid. The chemical reactivity of glutamic acid with alginates rich in mannuronic acid residues explains the well-established effect of this type of polysaccharide in extrusion processing. In addition, the apparent reactivity of glutamic acid residues in these types of reactions may be a possible reason for the ease with which soya and gluten (proteins rich in glutamic acid residues) can be extruded, while proteins with less of these residues are more difficult to extrude.     

味精中焦谷氨酸检测方法的研究进展

焦谷氨酸是一种环状氨基酸, 是许多氨基酸和蛋白质生成过程中的中间产物, 广泛存在于动植物界。在味精生产过程中, 谷氨酸受热会脱水环化成焦谷氨酸, 影响谷氨酸的提取收率, 所以为了对焦谷氨酸进行控制, 在味精生产过程中对其检测是非常必要的。本文综述了焦谷氨酸的结构及性质, 并对味精生产过程可能产生焦谷氨酸的环节做了阐述, 重点介绍了焦谷氨酸的检测方法：化学法和高压液相色谱法, 并对高压液相色谱法进行了展望。     

Pigments of Monascus

A chemically defined medium with glutamic acid as nitrogen source was devised for the culture of two species of Monascus (M. ruber and M. purpureus), resulting in optimum production of their pigments and their chemical structures (both free and complexed) were compared. Structural data on two major complex pigments in aqueous solution were obtained by IR, UV, NMR and MS. They were free pigments linked to glutamic acid by amino groups, where nitrogen replaced the pyronoid oxygen.     

稀土镧在谷氨酸发酵生产中的应用

研究了在谷氨酸发酵工业生产条件下,稀土促进菌体产酸、提高谷氨酸产量的最佳效果,以及稀土的加入方法和生产工艺对稀土的作用效果所产生的影响。研究表明,在大生产工艺条件下,发酵培养基中含有1mg/L碳酸镧时能明显增加谷氨酸产量,提高发酵水平,但其作用效果也受到一些生产工艺的影响。     

味精清洁生产蒸发凝结水再利用研究

在味精清洁生产工艺中 ,利用四效蒸发技术来浓缩谷氨酸等电结晶母液 ,所得的蒸发凝结水因COD值稍高而不能直接排放。为解决这一问题并节约水资源 ,文章中研究了将凝结水作为配料水应用于味精生产的可行性。通过与自来水进行比较 ,考察了其对液化、糖化和发酵过程的影响。分别用凝结水和自来水作为配料水进行制糖和发酵实验 ,结果二者均无明显差异。这一结果表明 ,蒸发凝结水应用于谷氨酸发酵是可行的。     

二次接种叠加生物素的谷氨酸发酵工艺研究

由于受到发酵罐溶氧条件的限制,在高浓度生物素的谷氨酸发酵中往往出现产酸与糖酸转化率不协调的现象,针对这一现象,研究了二次接种叠加生物素的谷氨酸发酵工艺。在试验所用的发酵罐中,采用8.0μg/L生物素浓度的培养基作为发酵基础培养,经过一段时间发酵后,接入第二次种子液以及3.0μg/L(发酵液初始体积)的生物素量,通过适当的发酵控制,产酸水平达到139.6g/L,糖酸转化率高达62.80%,单罐谷氨酸产量比一次接种添加8.0μg/L生物素的发酵工艺提高了15.78%。     

The influence of monoacylglycerol and L‐glutamic acid on the viscoelastic properties of wheat flour dough and sensory characteristics of French loaf product

BACKGROUND: The influence of monoacylglycerol Rimulsoft Super(V) and L ‐glutamic acid added to wheat flour dough was studied. Properties of the doughs were evaluated on the basis of chemical analysis and rheological measurements on a farinograph. Bakery products made from these doughs were subsequently subjected to sensory analyses. RESULTS: It was found that L ‐glutamic acid influenced the water absorption in dough more (50.0 g kg^?1; water absorption 56.6%) than monoacylglycerol Rimulsoft Super(V) (50.0 g kg^?1; water absorption 55.0%). Farinograph measurements showed that doughs with the addition of L ‐glutamic acid resembled flour containing high‐quality gluten, but dough with the addition of monoacylglycerol Rimulsoft Super(V) corresponded to ‘weak’ flour. Sensory analyses revealed that, in comparison with the control sample of French loaf, the saliva‐absorbing capacity increased in the French loaf with the highest addition of L ‐glutamic acid (30.0 g kg^?1). Deterioration in quality and texture in French loaf with addition of L ‐glutamic acid (8.0 g kg^?1, 30.0 g kg^?1) was noted. No other statistically significant differences were found. CONCLUSION: It is acceptable to add both additives to dough in order to modify its rheological properties. Copyright © 2010 Society of Chemical Industry     

Production of malic and succinic acids by sugar-tolerant yeast <Emphasis Type="Italic">Zygosaccharomyces rouxii</Emphasis>

Zygosaccharomyces rouxii V19 was grown in YPG medium (yeast extract, 0.5%, peptone, 1.0%, glucose, 10%). Fermented broth was purified through a series of ion-exchange columns and ODS column and the purified sample was TMS-esterified. Malic and succinic acids were identified with GC-MS analysis. The yeast was cultivated under various cultural conditions and quantitative determination of the organic acids was carried out with HPLC on Shodex column. Glucose concentration of 30%, initial pH 5.0, and 25 °C incubation temperature were the optimum conditions. Inclusion of glutamic, malic, and succinic acid precursors in the medium increased the production of malic acid. On the other hand, only addition of malic acid enhanced the production of succinic acid. Maximum amount of malic acid produced was 74.9 g/L (32.8% yield, based on glucose consumption) in the medium with 0.5% glutamic acid supplement, and that of succinic acid was 7.7 g/L (8.1% yield) when 0.3% malic acid was added in the medium.