Surplus dietary isoleucine intake enhanced monounsaturated fatty acid synthesis and fat accumulation in skeletal muscle of finishing pigs

Background: Isoleucine(Ile) has been implicated in the regulation of energy homeostasis and adipogenesis.However,the impact of surplus dietary Ile intake on muscle lipogenesis remains unknown.The present study aimed to investigate the impact of dietary supplementation of extra-Ile on lipogenesis,fatty acid profile and lipid accumulation in skeletal muscle in finishing pigs.Methods: Forty-eight barrows with initial body weight of 77.0 ± 0.1 kg were allotted to one of two groups and fed diets containing 0.39%,0.53% standardized ileal digestible(SID) Ile with six replicates per treatment and four pigs per replicate for 30 d.Results: Dietary Ile intake significantly improved the intramuscular fat(IMF) content and monounsaturated fatty acid(MUFA) concentration in the skeletal muscle(P < 0.05),and decreased the drip loss and shear force(P < 0.05) without influencing the growth performance of pigs(P > 0.05).Moreover,the phosphorylation of adenosine monophosphate activated protein kinase α(AMPKα) and acetyl coenzyme A carboxylase(ACC) proteins that monitor lipid metabolism were decreased in skeletal muscle of pigs offered extra-Ile diet(P < 0.05).The mRNA expression of adipose-specific genes adipocyte determination and differentiation factor 1(ADD1),fatty acid synthase(FAS),and stearoyl-CoA desaturase(SCD) were upregulated and the activity of SCD was increased as well(P < 0.05).Conclusions: Surplus dietary Ile intake could increase IMF accumulation and MUFA synthesis in skeletal muscle through depressing the phosphorylation of AMPKα-ACC and stimulating the expression and activity of SCD,and increasing the capability of lipogenesis in skeletal muscle.

Photofragmentation of Isoleucine by Vacuum Ultraviolet Photoionization

Vacuum ultraviolet photon-induced ionization and dissociation of isoleucine are investi- gated with synchrotron radiation photoionization mass spectroscopy and theoretical cal- culations. The main fragment ions at m/z=86, 75, 74, 69, 57, 46, 45, 44, 41, 30, 28, and 18 from isoleucine are observed in the mass spectrum at the photon energy of 13 eV. From the photoionization efficiency curves, appearance energies for the principal fragment ions CsH12N＋ （rn/z=86）, C2H5NO2＋ （m/z=75）, C5H9＋ （rn/z=-69）, C4H9＋ （m/z=57）, and CH4N＋ （m/z=30） are determined to be 8.844-0.07, 9.254-0.06, 10.20-4-0.12, 9.254-0.10, and 11.05＋0.07 eV, respectively, and possible formation pathways are established in detail by the calculations at the B3LYP/6-31＋＋G（d, p） levels. These proposed channels include simple bond cleavage reactions as well as reactions involving intermediates and transition structures. The experimental and computational appearance energies or barriers are in good agreement.

Efficient Synthesis of 3,5,6,7-Tetrahydro-4H-cyclopenta [4,5] thieno [2,3-d] Pyrimidin-4-ones

The title compounds 3,5,6,7-tetrahydro-4H-cyclopenta[4,5]thieno[2,3-d]pyrimidin-4-ones（6） were synthesized by base catalytic reactions of secondary amines with carbodiimides 4, which were obtained from the aza-Wittig reaction of iminophosphoranes（3） with aromatic isocyanates.

Dietary isoleucine improved flesh quality,muscle antioxidant capacity,and muscle growth associated with AKT/TOR/S6K1 and AKT/FOXO3a signaling in hybrid bagrid catfish(Pelteobagrus vachelli♀×Leiocassis longirostris♂)

Background:Muscle is the complex and heterogeneous tissue,which comprises the primary edible part of the trunk of fish and mammals.Previous studies have shown that dietary isoleucine(Ile)exerts beneficial effects on growth in aquatic animals.However,there were limited studies regarding the benefits of Ile on fish muscle and their effects on flesh quality and muscle growth.Thus,this study was conducted to explore whether dietary Ile had affected flesh quality and muscle growth in hybrid bagrid catfish(Pelteobagrus vachelli♀×Leiocassis longirostris♂).Methods:A total of 630 hybrid fish,with an initial average body weight of 33.11±0.09 g,were randomly allotted into seven experimental groups with three replicates each,and respectively fed seven diets with 5.0,7.5,10.0,12.5,15.0,17.5,and 20.0 g Ile/kg diets for 8 weeks.Results:In the present study,we demonstrated that Ile significantly:(1)increased muscle protein and lipid contents and the frequency distribution of myofibers with≤20μm and≥50μm of diameter;(2)improved pH value,shear force,cathepsin B and L activities,hydroxyproline content,resilience,cohesiveness,and decreased cooking loss,lactate content,hardness,springiness,gumminess,and chewiness;(3)decreased reactive oxygen species(ROS),malondialdehyde(MDA),and protein carbonyl(PC)contents,GCLC and Keap1 mRNA levels,and up-regulated CuZnSOD,CAT,GPX1a,GST,and Nrf2 mRNA levels;(4)up-regulated the insulin-like growth factor 1,2(IGF-1,IGF-2),insulin-like growth factor 1 receptor(IGF-1R),proliferating cell nuclear antigen(PCNA),Myf5,Myod,Myog,Mrf4,and MyHC mRNA levels,and decreased MSTN mRNAlevel;(5)increased muscle protein deposition by activating AKT-TOR-S6K1 and AKT-FOXO3a signaling pathways.Conclusion:These results revealed that dietary Ile improved flesh quality,which might be due to increasing nutritional content,physicochemical,texture parameters,and antioxidant ability;promoting muscle growth by affecting myocytes hyperplasia and hypertrophy,and muscle protein deposition associated with protein synthesis and degradation signaling pathways.Finally,the quadratic regression analysis of chewiness,ROS,and protein contents against dietary Ile levels suggested that the optimal dietary Ile levels for hybrid bagrid catfish was estimated to be 14.19,12.36,and 12.78 g/kg diet,corresponding to 36.59,31.87,and 32.96 g/kg dietary protein,respectively.

Isoleucine, an Essential Amino Acid, Induces the Expression of Human <i>β</i>Defensin 2 through the Activation of the G-Protein Coupled Receptor-ERK Pathway in the Intestinal Epithelia

Anti-microbial peptides are essential for the intestinal innate immunity that protects the intestinal epithelia from attacks by foreign pathogens. Human β-defensin (HBD) is one of the pivotal anti-microbial peptides that are expressed in the colonic epithelia. This study investigated the effect and the signaling mechanism of inducible β-defensin HBD2 by an essential amino acid, isoleucine (Ile) in colonic epithelial cells. Here we examined the expression level of HBD2 on induction of Ile in epithelial cells, and checked this pathway. HBD2 mRNA was induced by co-incubation with IL-1α and Ile in Caco2 cells, but not by Ile alone. An inhibitor of either ERK or Gi, a subunit of G-proteins, reduced the induction of HBD2 mRNA by Ile. The treatment with Ile also increased the intracellular calcium ion concentration, thus suggesting that the GPCR and ERK signaling pathway mediate the effects of Ile. These results indicate that an essential amino acid, Ile, enhances the expression of an inducible β-defensin, namely HBD2, by IL-1α through the activation of GPCRs and ERK signaling pathway. The administration of Ile may therefore represent a possible option to safely treat intestinal inflammation.

Chronic Supplementation with L-Isoleucine Alone or in Combination with Exercise Reduces Hepatic Cholesterol Levels with No Effect on Serum Glucose, Insulin, or Lipids in Rats Fed a High Fructose Diet

The thought of using branched-chain amino acids (BCAA) in the prevention and treatment of certain disorders is becoming increasingly popular. Individual BCAA use has been associated with improving glucose tolerance and liver disease. Previous studies have cited improvements in glucose metabolism with a single dose of L-isoleucine (ILE). However, it is still unclear whether chronic consumption of ILE has any direct benefit. The objective of this study was to examine the influence of chronic ILE supplementation alone or in combination with exercise on fasting serum glucose, insulin, lipids, and lipoprotein cholesterol levels;glucose tolerance;and hepatic lipids in rats. Male Sprague-Dawley rats (n = 40) were divided into Control (low fructose diet);High Fructose diet (HF);HF plus 1.5% ILE (HF + ILE);HF plus exercise (HF + EX);and HF plus 1.5% ILE and exercise (HF + ILE + EX). The HF diets consisted of 70% kcalories from fructose. After 6 weeks of treatment, no significant differences were observed between groups for changes in fasting serum glucose, insulin, lipids, or lipoprotein cholesterol levels. However, hepatic total cholesterol was significantly lower in the HF + ILE + EX compared to the Control and HF, while, the HF + ILE had significantly lower hepatic free cholesterol compared to the HF. We also found no differences between groups for serum glucose response following an oral glucose tolerance test. In conclusion, our study shows that ILE supplementation in rats does not influence serum glucose and lipid biomarkers but may have an influence on lipid metabolic pathways within the liver.

Application of quartz crystal nanobalance in conjunction with a net analyte signal based method for simultaneous determination of leucine, isoleucine and valine

The aim of the present investigation was to develop a biosensor for the detection of amino acids, Leucine, Isoleucine and Valine based on a quartz crystal nanobalance. leucine (Leu), isoleucine (Ile), and valine (Val) were selectively determined by quartz crystal nanobalance (QCN) sensor in conjunction with net analyte signal (NAS)-based method called HLA/GO. An orthogonal design was applied for the formation of calibration and prediction sets including Leu, Ile and Val compounds. The selection of the optimal time range involved the calculation of the net analyte sig-nal regression plot in any considered time window for each test sample. The searching of a region with maximum linearity of NAS regression plot (minimum error indicator) and minimum of PRESS value was carried out by applying a moving window strategy. On the base of obtained results, the differences on the adsorption profiles in the time range between 1 and 300 s were used to determine mixtures of compounds by HLA/GO method. The results showed that the method was successfully applied for the determina-tion of Leu, Ile and Val.

SYNTHESIS, CHARACTERIZATION OF CHIRAL POLY(ESTER AMIDE)S DERIVED FROM L-ISOLEUCINE

A series of new optically active aromatic poly(ester amide)s containing a chiral group in the side chain prepared from the p-toluenesulfonic acid salt of o,o'-bis(leucyl)-hexanediol (TS-+LHD+TS-) and p-phthaloyl chloride and styrene-2,5- dicarbonyl chloride styrene have been synthesized by interfacial polymerization. The structure of the monomer is elucidated by FT-IR and elemental analysis. The thermal properties of the polymers were studied by DSC and TGA. The chiroptical properties of the above polymer have also been studied by circular dichroism (CD) spectroscopy. Results indicated that these polymers form helical structures.

异亮氨酸对断奶仔猪睾丸生长发育、抗氧化能力和生殖激素水平的作用研究

试验旨在研究不同水平异亮氨酸对断奶仔猪睾丸生长发育、抗氧化功能及生殖激素的影响。选取28日龄断奶仔猪18头,随机分成3组,每组6个重复,每个重复1头仔猪。各组饲粮异亮氨酸水平分别为0.8%、1.0%、1.2%。试验期21 d。结果显示:与0.8%异亮氨酸组(对照组)相比,1.0%异亮氨酸组睾丸尺寸和重量均显著升高(P<0.05);1.0%和1.2%异亮氨酸组睾丸组织曲细精管横截面积及曲细精管周长均显著升高(P<0.05);1.0%异亮氨酸组睾丸组织谷胱甘肽过氧化物酶(GSH-Px)活性显著增高(P<0.05),丙二醛(MDA)含量显著降低(P<0.05),1.0%异亮氨酸对下丘脑-垂体-睾丸性腺轴生殖相关指标具有明显的调控作用。研究表明,1.0%异亮氨酸可以缓解仔猪断奶导致的氧化应激,通过改变下丘脑-垂体-睾丸组织性腺轴生殖相关激素分泌水平,影响仔猪睾丸形态及生殖相关指标。

精氨酸和异亮氨酸对白羽肉鸡肠道发育、免疫器官指数和肉品质的影响

为研究无抗日粮中添加精氨酸和异亮氨酸对白羽肉鸡肠道发育、免疫器官指数和肉品质的影响,本试验选用健康的1日龄罗斯308肉仔鸡720只,随机分成4个处理,每个处理6个重复,每个重复30只,分为对照组(基础饲粮)、抗生素组(基础饲粮+75 mg/kg金霉素)、AL2组(基础饲粮+2%精氨酸和异亮氨酸)、AL5组(基础饲粮+5%精氨酸和异亮氨酸)。研究结果表明:(1)与对照组相比,抗生素组、AL2组和AL5组商品肉鸡21 d的空肠绒毛长度分别提高7.97%、15.94%和13.69%(P<0.05),回肠绒毛长度分别提高15.38%、33.34%和39.05%(P<0.05),21 d的空肠绒腺比提高11.27%、18.18%和16.54%(P<0.05),回肠绒腺比分别提高22.27%、38.93%和44.78%(P<0.05);同时,与抗生素组相比,AL2组和AL5组肉鸡21 d回肠的绒毛长度分别提高15.57%和20.51%(P<0.05),绒腺比提高13.63%和18.41%(P<0.05)。(2)AL2组和AL5组42 d的脾脏指数、胸腺指数和法氏囊指数分别较对照组提高29.76%和31.95%、36.519%和43.70%、47.61%和63.37%(P<0.05);AL2组和AL5组42 d的胸腺指数分别较抗生素组提高24.39%和30.95%(P<0.05)。(3)抗生素组、AL2组和AL5组的胸肌肉色值分别较对照组提高22.21%、15.27%和22.97%(P<0.05),腿肌肉色值分别提高14.98%、15.81%和16.83%(P<0.05),腿肌的滴水损失分别降低12.85%、20.26%和26.92%(P<0.05);AL2组的胸肌肉色a值和b值较抗生素组分别提高24.30%和26.84%(P<0.05),腿肌肉色的b值较对照组降低17.64(P<0.05)%;AL5组的腿鸡滴水损失较抗生素组和AL2组分别降低16.14%和8.35%(P<0.05)。综上所述,日粮添加精氨酸和异亮氨酸能促进肉鸡的肠道和免疫器官发育,提高肉品质,可在一定程度上替代抗生素。

日粮补充异亮氨酸对肉鸡生长性能、肉品质和肠道形态的影响

试验旨在研究在日粮中补充异亮氨酸(Ile)对肉鸡生长性能、肉品质和肠道形态的影响。选取1日龄健康且状态良好爱拔益加(AA)肉仔鸡10500只,随机分为3组,每组7个重复,每个重复500只鸡。对照组(CON组)饲喂基础日粮,试验组饲喂在基础日粮基础上分别添加400 mg/kg Ile(ILE400组)和800 mg/kg Ile(ILE800组)的试验日粮。试验期42 d。结果表明:与对照组相比,ILE400组和ILE800组能够显著降低肉鸡的料重比(F/G)和死淘率(P<0.05),ILE400组肉鸡平均日增重(ADG)显著升高(P<0.05);ILE400组胸肌和腿肌亮度(L*)值和红度(a*)值显著升高(P<0.05),ILE400组胸肌黄度(b*)值显著高于ILE800组(P<0.05);ILE400组和ILE800组能够显著提高肉鸡腿肌中粗蛋白含量(P<0.05)。此外,与对照组和ILE800组相比,ILE400组能够显著提高胸肌雷帕霉素靶蛋白(mTOR)mRNA相对表达量和小肠绒毛高度(P<0.05)。ILE400组真核翻译起始因子4E结合蛋白1(4EBP1)mRNA相对表达量显著高于ILE800组(P<0.05)。由此可见,日粮中补充400 mg/kg Ile(前、中、后期日粮中总Ile水平为1.01%、0.90%和0.87%)能够提高肉鸡的生长性能,降低死淘率,改善肉鸡的肉色,通过激活mTOR通路相关基因的表达,提高肌肉中蛋白质的含量,并且有利于改善肠绒毛发育。

异亮氨酸在家禽生产中的应用研究进展

蛋白饲料资源短缺已成为制约畜牧业发展的重要因素,非常规蛋白质原料的开发以及低蛋白饲粮的配制技术已成为目前研究的重点之一。在当前深入推广实施的饲用豆粕减量替代行动与积极推广低蛋白质低豆粕多元化饲粮配制技术的行业背景下,异亮氨酸在家禽营养中的应用备受重视。异亮氨酸是畜禽机体内重要的必需氨基酸之一,具有促进蛋白质合成、修复肌肉、调控血糖水平和调节脂肪代谢等生理功能。本文就异亮氨酸的营养生理功能及其在家禽上的应用效果等方面进行综述,为其在家禽生产中的应用及相关机制研究提供参考。

异亮氨酸缓解猪睾丸支持细胞氧化应激作用

目的:研究异亮氨酸缓解过氧化氢诱导的猪睾丸支持细胞氧化应激的保护作用,并确定不同浓度异亮氨酸对缓解氧化应激导致的睾丸支持细胞活力下降的最佳浓度,及最佳异亮氨酸浓度对猪睾丸支持细胞的增殖、凋亡和抗氧化水平的影响。方法:利用CCK-8法检测细胞活力,筛选在氧化应激模型下异亮氨酸保护猪睾丸支持细胞的最适浓度。应用流式细胞术检测最适异亮氨酸浓度下支持细胞的周期和凋亡情况。应用试剂盒检测总超氧化物歧化酶(Superoxide Dismutase,T-SOD)、总抗氧化能力(Total Antioxidant Capacity,T-AOC)、谷胱甘肽过氧化物酶(Glutathione Peroxidase,GSH-Px)和丙二醛(Malondialdehyde,MDA)的表达量。结果:与氧化应激丙氨酸等氮对照组和其他浓度氧化应激异亮氨酸组相比,32 mmol/L氧化应激异亮氨酸组细胞增殖活力显著升高。与氧化应激不加药组和氧化应激丙氨酸等氮对照组相比,氧化应激异亮氨酸组细胞分化G_(0)/G_(1)期比例相对较低,S期和G_(2)/M期比例无明显差异。与氧化应激不加药组相比,氧化应激异亮氨酸组细胞凋亡比例呈显著降低,与氧化应激等氮对照组相比,氧化应激异亮氨酸组细胞凋亡比例无明显差异。与无氧化应激丙氨酸等氮对照组和氧化应激丙氨酸对照组相比,异亮氨酸极显著增强T-SOD的活性,也极显著增加氧化应激异亮氨酸组T-AOC,而对GSH-Px和MDA没有显著影响。结论:在本试验条件下32 mmol/L异亮氨酸效果最佳,有效缓解氧化应激导致的细胞活力下降、细胞周期紊乱和细胞凋亡。

草鱼幼鱼对异亮氨酸的需要量

以初始体重（8．25±0．37）g的草鱼幼鱼为试验对象，分别采用异亮氨酸（isoleucine，Ile）水平为0．77％、1．07％、1．37％、1．67％、1．97％和2．27％6组等氮（粗蛋白35．25％）半纯化日粮对草鱼进行了72d生长试验，研究其日粮异亮氨酸需要量。结果表明：（1）日粮Ile水平为1．67％时，草鱼增重率、特定生长率和蛋白质效率最高，饲料系数最低；鱼体空壳率和肥满度达到最大值，内脏指数最小；草鱼体水分、体脂最低，体蛋白、灰分最高；肌肉水分最低，粗蛋白最高。而各水平之间肌肉粗脂肪无显著差异（P〉0．05）；日粮Ile水平为1．67％时，草鱼肌肉Ile含量和肌肉氨基酸总量最高。（2）随日粮Ile水平增加，肌肉RNA／DNA呈先升后降趋势，Ile 1．67％水平组最高；而肝脏谷氨酸脱氢酶却呈先降后升趋势，Ile 1．67％水平组最低。血氨在Ile 0．77％～1．67％水平组之间处于稳定状态，高于1．67％水平后呈上升趋势。血清白蛋白受日粮Ile水平的影响不显著（P〉0．05）。（3）随日粮Ile水平增加，血清甘油三酯和胆固醇均呈先降后升趋势，且在Ile 1．67％水平组，两项指标均为最低值，显著低于其他水平组（P〈0．05）。根据增重率、特定生长率、饲料系数和蛋白质效率与日粮Ile水平的二次曲线关系，确定草鱼幼鱼日粮（粗蛋白35．25％）Ile适宜需要量范围为1．41％～1．49％（日粮基础）或4．0％～4．23％（日粮蛋白基础）。

L-异亮氨酸发酵培养基的响应面法优化

借助于SAS软件 ,采用Plackett Burman试验设计法及响应面法分析 ,对L 异亮氨酸产生菌BrevibacteriumflavumTC 2 1进行了发酵培养基的优化研究。在初始发酵培养基的基础上寻优 ,优化后的发酵培养基使TC 2 1菌株的L 异亮氨酸产率提高了 2 2 5 2 %。

谷物中赖氨酸含量测定方法的探析

在检测小麦中赖氨酸的含量时,用异亮氨酸代替亮氨酸作标准曲线.结果表明:适当延长加热时间,在556 nm处异亮氨酸的吸光值比530 nm处亮氨酸要稍高,异亮氨酸与茚三酮反应产生的颜色比亮氨酸要更明显,可以用异亮氨酸做标准曲线来检测小麦中赖氨酸的含量.同时得出,脱脂面粉比普通面粉的赖氨酸含量要稍高,脱脂与否对小麦中赖氨酸含量的测定有一定的影响.

0～21日龄北京鸭色氨酸、苏氨酸、异亮氨酸需要量的研究

在日粮中添加不同水平的苏氨酸、异亮氨酸、色氨酸,研究0～21日龄北京鸭对这3种氨基酸的需要量。试验采用了3×3×3因子设计,3种氨基酸各设3个水平,形成27个处理,每处理3个重复,每重复饲养14只鸭。其中苏氨酸和异亮氨酸的添加水平均为7.0,8.0和9.0g/kg;色氨酸的添加水平为2.5,3.0和3.5g/kg。试验结果表明,在粗蛋白(CP)为202.6g/kg,代谢能(ME)为12.51MJ/kg的玉米-豆粕-花生粕型日粮中,苏氨酸可显著影响15～21日龄北京鸭平均日采食量和21日龄时的尿酸浓度;色氨酸可显著影响15～21日龄北京鸭的料肉比;各测定指标在异亮氨酸各水平间差异不显著(P>0.05);在该类型日粮中,0～21日龄北京鸭饲料中异亮氨酸、苏氨酸和色氨酸水平应分别不高于7.0,7.0和2.5g/kg。

饲料异亮氨酸水平对卵形鲳鲹消化酶活性和免疫指标的影响

实验旨在研究饲料异亮氨酸(Ile)水平对卵形鲳鲹(Trachinotus ovatus)消化酶活性和免疫指标的影响。以鱼粉、豆粕、花生粕和L-晶体氨基酸为蛋白源,配制含粗蛋白430 g·kg^(-1)的6种等氮饲料,各组分别含有13.2 g·kg^(-1)、15.7 g·kg^(-1)、18.2 g·kg^(-1)、20.7 g·kg^(-1)、23.2 g·kg^(-1)和25.7g·kg^(-1)(以干物质计)异亮氨酸。每组3个重复,每个重复随机放置20尾鱼[初始体质量(6.36±0.03)g],实验时长8周。结果显示,各实验组的肠淀粉酶和胃蛋白酶活性、血清总抗氧化能力(T-AOC)、溶菌酶(LZM)活性、免疫球蛋白M和补体(C3和C4)浓度均随着饲料Ile水平的升高而先上升后下降,这5个指标的较高值出现在18.2 g·kg^(-1)和20.7 g·kg^(-1)组,而较低值则出现在13.2 g·kg^(-1)和25.7 g·kg^(-1)组,上述4组与其他2组差异显著。血清尿素氮和丙二醛(MDA)浓度的变化趋势则与上述7个指标相反,较低值出现在18.2 g·kg^(-1)和20.7 g·kg^(-1)组,且显著低于其他4组。血清超氧化物歧化酶(SOD)活性则随着饲料Ile水平的增加而显著升高,18.2~25.7 g·kg^(-1)这4组SOD活性没有显著性差异。综上所述,饲料Ile水平为18.2~20.7 g·kg^(-1)时,卵形鲳鲹具有较好的消化性能和免疫机能。

亮氨酸与异亮氨酸在金/银核-壳复合纳米粒子上的吸附状态

研究了亮氨酸和异亮氨酸的拉曼光谱及其在金/银核-壳复合纳米粒子上的表面增强拉曼光谱(SERS);归属、分析了不同振动模式引起的振动峰位变化.拉曼光谱中,亮氨酸的甲基摇摆(ω(CH_3))拉曼位移为962,945,924 cm^(-1),甲基变形(δ_(as)(CH_3))为1454,1408,cm^(-1),异亮氨酸的分别为922 cm^(-1)和1448,1420,1394 cm^(-1).在酸性和碱性条件下不同浓度的SERS中,各对应基团振动峰位差异更明显.初步阐述了亮氨酸与异亮氨酸浓度与SERS关系,并推测了在金/银核-壳复合粒子表面的吸附模型.

均匀设计在L-异亮氨酸发酵中的应用

本试验用均匀设计方法考查了9种培养基组成对L-异亮氨酸产生菌钝齿棒状杆菌(Cory-nebacterium crenatum)A11发酵的影响,获得优化配比为:葡萄糖12%,硫酸铵2%,磷酸二氢钾0.1%,磷酸氢二钾0.45%,硫酸镁0.055%,生物素1μg,硫胺素15μg,硫酸亚铁2ppm,硫酸锰2ppm,碳酸钙4%,pH7.0～7.2。在此条件下,菌株A11可产生L-异亮氨酸15.1mg/ml。与正交设计相比,均匀设计具有试验次数少,工作效率高和便于分析因素影响等优点。