Optimizing Conditions Analysis of Levan by Whole-cell Biocatalysis with Corynebacterium glutamicum

This experiment was aimed to explore a new way for microbial synthesis of Levan and optimize its synthesis conditions.Levan synthesis by whole-cell catalysis using recombinant Corynebacterium glutamicum that transferred into levansucrase,and the response surface method were used to optimize the synthesis conditions with Levan yield as the response value.Firstly,the Plackett-Burman design was used to screen out three main factors affecting yield (sucrose concentration,final concentration of ethanol in Levan extraction and Ca²⁺ concentration) from 7 related factors (sucrose concentration,bacterial concentration,transformation time,transformation pH,Ca²⁺ and Mg²⁺ concentration in PBS,and final concentration of ethanol in Levan fructan extraction).Then the three most important factors selected were used for the steepest climbing test to approach the region of maximum response value,and finally use the BBD response surface method to determine the interaction between the three main factors and the best synthesis conditions.The results showed that the average yield of Levan was 0.069 g/mL in the initial experiment.The response surface method was used to optimize the whole-cell biocatalysis of Levan by Corynebacterium glutamate.The most influential factor was sucrose concentration,the second was the final concentration of ethanol,and the last was the Ca²⁺ concentration in the transformation solution.When the sucrose concentration was 52.71%,the final ethanol concentration was 85.31%,and the Ca²⁺ concentration was 0.04 g/L,the average yield of Levan synthesized by recombination Corynebacterium glutamate was 0.238 g/mL,which was close to the model's predicted maximum value of 0.233 g/mL,and the conversion rate was about 44%.The conversion rate was 1.9 times higher than the initial test,and the yield was 3.4 times higher than the initial test.The results provided the basis for Levan industrial production,and laid the foundation for its research in animal medicine and nutrition.     

类植物乳杆菌L-ZS9培养基及培养条件的优化

类植物乳杆菌L-ZS9分离自发酵肉类食品,作为益生菌制剂和发酵剂在乳品行业具有良好的应用潜力。为实现类植物乳杆菌L-ZS9的高密度培养,以MRS培养基为基础进行培养基的优化,并优化培养条件。以单因素试验初步确定培养基中所用的碳源和氮源,通过Plackett-Burman试验确定出培养基成分与培养条件中影响较大的因素,经最陡爬坡试验确定各因素的水平,再通过响应面旋转中心组合试验拟合出菌体密度与因素水平间的方程,从而确定优化后的培养条件。结果表明：培养基中所用的碳源为蔗糖,氮源为酵母粉;经过验证实验得到的优化     

一株同时降解玉米赤霉烯酮和黄曲霉毒素B_1的谷氨酸棒状杆菌及其降解特性研究

试验旨在筛选同时降解玉米赤霉烯酮(ZEN)和黄曲霉毒素B_1(AFB_1)的菌株,并研究其对两种毒素的降解特征。从土壤及鸡、驴的食糜中筛选出9株可同时降解ZEN和AFB_1的菌株;编号为406的菌株经形态学观察和16S rDNA鉴定为谷氨酸棒状杆菌(Corynebacterium glutamate)。谷氨酸棒状杆菌406降解ZEN和AFB_1活性成分存在于发酵上清液中,其对ZEN和AFB_1的降解率分别为50%和58%。通过热、胰蛋白酶、十二烷基硫酸钠(SDS)处理,初步确定降解活性物质为一种胞外酶。上清液对ZEN和AFB_1的最适降解温度为67℃,最适pH值为8。本研究筛选到的同时降解ZEN和AFB_1的谷氨酸棒状杆菌菌株406为食品和饲料中ZEN和AFB_1的生物降解提供菌种资源。     

饲用枯草芽孢杆菌SR096产孢培养基及培养条件的优化

试验旨在为了降低枯草芽孢杆菌SR096的工业生产成本和提高发酵液的芽孢含量,采用单因素试验和响应面法试验设计对菌株SR096的培养条件和发酵培养基组分优化,优化后的培养基组分为:葡萄糖7.5 g/L、玉米粉15.7 g/L、黄豆粉45.0 g/L、柠檬酸钠4.5 g/L、碳酸钙2.0 g/L、硫酸镁1.0 g/L,经验证在5 L发酵罐中以接种量3%、37℃、250 r/min条件下培养30 h,枯草芽孢杆菌SR096发酵液的活菌含量为1.67×10^10 CFU/mL,芽孢含量为1.56×10^10 CFU/mL,芽孢率为93.3%,为枯草芽孢杆菌SR096后期的产业化放大和推广应用奠定基础。     

枯草芽孢杆菌产纤维素酶活力条件的研究

试验研究枯草芽孢杆菌(Bacillus subtilis)产纤维素酶(CMCA)的活性条件.以杨树叶、酒糟、红薯秧、麸皮为主要试验碳源,通过单因素试验确定最佳碳源,并通过单因素试验和响应面法优化分析碳源添加量、产酶温度、装液量对纤维素酶活力的影响.结果 表明,产酶最佳的培养条件为装液量100.510 mL、产酶温度36...     

响应面法优化贝莱斯芽孢杆菌P9菌株生孢培养基及条件的研究北大核心

研究旨在优化贝莱斯芽孢杆菌P9菌株的生孢培养基及条件。试验以贝莱斯芽孢杆菌P9的菌体浓度和生孢率为指标,通过单因素结合响应面试验对生孢培养基成分进行优化。结果显示,最佳生孢培养基成分为葡萄糖2.0 g/L、牛肉膏4.0 g/L、酵母浸粉4.0 g/L,MgCl_(2)8.0 g/L、KH_(2)PO_(4)6.0 g/L、NaCl 0.01 g/L、1 mol/L的CaCl_(2)6 mL、1 mol/L的MnCl_(2)6 mL,此条件下贝莱斯芽孢杆菌P9的生孢率可达95.37%。研究表明,此方法可为贝莱斯芽孢杆菌在动物饲料生产中应用提供一定的试验基础。     

罗伊乳杆菌喷雾干燥工艺条件优化

本研究旨在优化猪源罗伊乳杆菌喷雾干燥工艺,提高喷雾干燥后罗伊乳杆菌的存活率。应用SAS V8.0统计分析软件中的二次正交旋转组合设计结合响应面法,优化出口温度、入口温度、脱脂乳浓度和入料速度等4个关键因素,分析上述因素与Y值的效应关系,并通过验证试验,检验预测结果的准确性。在本研究水平范围内,优化后的喷雾干燥工艺为:出口温度90℃、入口温度140℃、脱脂乳浓度20%、入料速度1500m L/h。应用优化后的喷雾干燥工艺进行了3次重复喷雾干燥试验,喷雾干燥的菌体平均存活率为74.91%,与预测值72.33%基本相符。结果表明,二次正交旋转组合实验设计结合响应面法可以用来优化罗伊乳杆菌喷雾干燥工艺。此外,应用优化的喷雾干燥工艺生产的制剂活菌数高,稳定性好,本试验为产业化开发提供了技术依据。     

响应面法优化嗜酸乳杆菌协同发酵豆粕的条件研究

试验分别利用产α-淀粉酶、蛋白酶、植酸酶以及β-甘露聚糖酶的功能性嗜酸乳杆菌对豆粕进行协同发酵,采用单因素试验研究了菌液接种量、发酵温度、发酵时间、液料比对酸溶蛋白含量的影响。在此基础上经过Box-Behnken设计试验,建立二次回归模型,得到最佳发酵条件为菌液接种量12.3%、发酵时间78.9 h、发酵温度36.8℃、液料比0.9 L/kg。在此条件下发酵豆粕,发酵豆粕的粗蛋白含量比发酵前提高了15.13%,酸溶蛋白含量提高了66.91%,半纤维素含量下降了24.93%,游离氨基酸含量是发酵前的11.62倍,胰蛋白酶抑制剂含量下降了91.68%,脲酶活性下降了95.67%,植酸含量下降了83.87%,发酵豆粕中的活菌数为1.37×10¹⁰ CFU/g。研究表明,该复合菌株发酵模式能够有效增加豆粕的营养成分,去除抗营养因子,从而提高豆粕的利用率,为发酵豆粕的工业化生产提供参考。     

应用响应面法优化副猪嗜血杆菌冻干保护剂

旨在对副猪嗜血杆菌HS1712冻干保护剂进行优化,提高菌株在冷冻干燥后的存活率。以冻干存活率为评价指标,对配方中甘油、海藻糖、甘露醇、聚乙烯吡咯烷酮(PVP)、牛血清白蛋白(BSA)等5种成分缺失,考察其对副猪嗜血杆菌冻干存活率的影响。在此基础之上,结合单因素变量试验,应用Box-Behnken响应面法对脱脂奶粉、甘油、海藻糖的添加比例进一步优化。结果表明,配方中甘油、海藻糖缺失后,副猪嗜血杆菌冻干存活率显著下降(P<0.05)。通过对Box-Behnken试验结果进行回归模型拟合,得到最佳添加比例为脱脂奶粉6.8%、甘油2.2%、海藻糖2.7%,具体配方成分及添加比例为脱脂奶粉6.8%、甘油2.2%、海藻糖2.7%、PVP 0.5%。使用优化后配方进行冻干验证,副猪嗜血杆菌HS1712平均冻干存活率为79.20%,与预测值(80.87%)无显著性差异(P>0.05),表示模型可靠。上述结果表明,优化后的冻干保护剂可显著提高副猪嗜血杆菌HS1712冷冻干燥后的存活率。     

Nutritional and functional values of lysed Corynebacterium glutamicum cell mass for intestinal health and growth of nursery pigs

The objective was to determine the nutritional and functional values of lysed Corynebacterium glutamicum cell mass (CGCM) as a protein supplement and a source of cell wall fragments supporting the growth and intestinal health of nursery pigs. Thirty-two pigs (21 d of age) were allotted to four treatments (n = 8) based on the randomized block design with sex and initial body weight (BW) as blocks. The main effect was the dietary supplementation of lysed CGCM (0, 0.7, 1.4, and 2.1%) replacing blood plasma and fed in two phases (10 and 11 d, respectively). Feed intake and BW were measured at the end of each phase. Pigs were euthanized on day 21 to collect jejunal tissue and mucosa to evaluate intestinal health. Ileal digesta were collected to measure the apparent ileal digestibility of nutrients in diets. Data were analyzed using Proc Mixed and Reg of SAS. Increasing daily intake of CGCM increased (linear; P < 0.05) ADG of pigs. Increasing CGCM supplementation affected (quadratic; P < 0.05) the relative abundance of Lactobacillaceae (minimum: 26.4% at 1.2% CGCM), Helicobacteraceae (maximum: 29.3% at 1.2% CGCM), and Campylobacteraceae (maximum: 9.0% at 1.0% CGCM). Increasing CGCM supplementation affected (quadratic; P < 0.05) the concentrations of immunoglobulin G (maximum: 4.94 µg/mg of protein at 1.0% CGCM) and protein carbonyl (PC; maximum: 6.12 nmol/mg of protein at 1.1% CGCM), whereas linearly decreased (P < 0.05) malondialdehyde (MDA) in the proximal jejunal mucosa. Increasing CGCM supplemention affected (quadratic; P < 0.05) intestinal enterocyte proliferation rate (maximum: 13.3% at 1.0% CGCM), whereas it did not affect intestinal morphology and the nutrient digestibility. In conclusion, supplementing 1.0% to 1.2%, reducing blood plasma supplementation by 0.7% to 0.9%, respectively, increased potential pathogenic microbiota associated in the jejunal mucosa resulting in increased immune response, enterocyte proliferation, and PC concentration. However, supplementing diets with 2.1% CGCM, replacing 1.5% blood plasma, improved growth performance, and reduced MDA without affecting nutrient digestibility, intestinal morphology, and microbiota in the jejunal mucosa. In this study, based on the polynomial contrast, supplementing 1.0% to 1.2% CGCM suppressed the benefits from blood plasma, whereas supplementing 2.1% CGCM showed functional benefits of CGCM with similar effects from blood plasma supplementation.     

响应面法优化微波萃取黄芪多糖工艺的研究

用微波萃取技术从内蒙古黄芪[Astragalus membranaceus(Fisch.)Bunge var.mongholious(Bunge)Hsiao]的干燥根中提取黄芪多糖。依据响应面法(RSM,Response surface methodology)原理,使用Design Expert(Static Made Easy,Minneapolis,MN,USA.version6.0.5,2001)软件的中心组合设计建立试验数学模型,对微波萃取黄芪多糖的提取时间、加热温度、提取溶液pH值及液料比进行优化组合。得到最优回归方程:Y=1.14+1·258E-003X1+0.16X2-0.027X3+0.15X4+0.032X11-0.047X22+0.025X33-0.047X22+0.025X33+0.029X44+0.043X1X2-0.018X1X3-0.059X1X4-0.027X2X3+2.263E-003X2X4+0.012X3X4。确定最优操作工艺参数为:微波加热时间20min、加热温度120℃、液料比8∶1、pH值10。粗多糖得率为32%,纯度为44.4%。测定值与预测值相关系数r为0.976。     

响应面法优化羊乳果蔬纸加工工艺

以羊乳、胡萝卜、山楂为主要原料生产羊乳果蔬纸,利用单因素试验并结合响应面分析法确定最佳的工艺参数;采用物性测定仪对羊乳果蔬纸进行粒子群算法结合质地剖面分析测定,比较山楂的加入形式对产品物性的影响.结果表明:制作羊乳果蔬纸时,以山楂汁的形式加入比以山楂浆的形式加入后所得的产品感官品质好;最佳工艺条件为:羊乳与胡萝卜的比例为5∶8(V/m),山楂汁与羊乳的比例为3∶5(V/V),复合稳定剂(以质量分数计,下同)0.87％、β-环糊精0.12％、护色剂0.1％、白砂糖10％、蜂蜜2.4％.在此最佳条件下,生产出的羊乳果蔬纸口味独特,酸甜可口,具有羊乳的奶香味和胡萝卜的香味,以及胡萝卜和山楂混合的色泽,外观宛如纸张,感官评分高达91.32分,与模型预测值的相对误差约为1.68％.     

响应曲面法优化精氨酸单糖苷合成工艺

利用响应曲面法对苹果酸催化合成精氨酸单糖苷(AF)条件进行优化。本文在单因素的基础上,以精氨酸单糖苷的合成率为考察指标,建立以反应时间、反应温度、料液比和苹果酸加入量的4因素3水平的实验模型,采用Design Expert 8.0.6分析软件对精氨酸单糖苷的合成条件进行优化研究。结果表明,合成AF的最佳工艺条件,反应温度为85℃,反应时间150 min,料液比1∶20 g/m L,苹果酸加入量为0.75 g。优化出来的最佳合成条件稳定可行、合成率高。     

响应面法优化乳双歧杆菌Z-1冷冻干燥保护剂配方

采用响应面法对乳双歧杆菌Z-1冷冻干燥保护剂配方进行优化。通过Plackett-Burman试验与最陡爬坡试验确定影响乳双歧杆菌Z-1冷冻干燥后活菌数的显著因素及最优响应值区间,再通过Box-Benhnken试验优化得到乳双歧杆菌Z-1冷冻干燥保护剂最佳配方。结果表明：海藻糖、蔗糖、L-半胱氨酸盐酸盐添加量是影响乳双歧杆菌Z-1冷冻干燥后活菌数的显著因素;经响应面试验设计建立活菌数和海藻糖、蔗糖、L-半胱氨酸盐酸盐添加量的回归模型,得到乳双歧杆菌Z-1冷冻干燥保护剂最佳配方为海藻糖添加量200.51 g/L、蔗糖添加量46.16 g/L、L-半胱氨酸盐酸盐添加量2.31 g/L,其他成分不变（脱脂乳粉添加量100 g/L、乳清蛋白粉20 g/L、甘油4 g/L、异抗坏血酸钠10 g/L、谷氨酸钠8 g/L）。     

响应曲面法优化紫羊茅包衣剂

以紫羊茅(Festuca rubra)种子为原料,研究了种子包衣剂中的各种成分和含量对包衣后种子发芽率的影响。在单因素试验的基础上,选择赤霉素、凹凸棒土和保水剂3个影响较大的因素,以发芽率为指标,采用响应曲面试验优化包衣剂成分和添加量。优化结果表明,每100 g紫羊茅种子包衣剂最佳组成为:4%的赤霉素乳油800倍液5 mL、凹凸棒土9 g、保水剂15 g,并混合牛粪末、化肥和粘土等成分,包衣质量增加至裸种的4～5倍。在此条件下,包衣后的紫羊茅种子在自然条件下发芽率可以达到94%。     

响应面法优化德氏乳杆菌保加利亚亚种NCFB2772发酵生产胞外多糖的培养条件优化

在单因素试验的基础上,采用响应面分析法,优化初始pH值、接种量、发酵温度3个主要培养条件对德氏乳杆菌保加利砸亚种NCFB2772（Lactobacillus delbrueckii subsp.bulgaricus NCFB2772, L.b NCFB2772）高产乳酸菌胞外多糖（extracellular polysaccharides, EPS）的影响。结果表明,初始pH6．5、接种量4．5％、发酵温度42℃、L．bNCFB2772合成EPS的量达到最大（907．8mg／L）。各因素对响应值的影响可用回归方程Y=-287．08＋39．83C1＋11．44C2＋18．54C3表示。     

响应面法优化产业化生产披萨干酪工艺参数

采用四因素五水平二次回归正交旋转组合试验设计,研究产业化生产披萨干酪的最佳优化工艺条件,选择发酵时间、凝乳时间、排乳清pH值以及NaCl添加量进行单因素试验,并验证回归模型的显著性.结果表明,产业化生产披萨干酪的最佳工艺条件为发酵时间27.5min、凝乳时间37.5min、排乳清pH6.3、NaC1添加量2.07％.此时最大得率24.78％.此时所制得的披萨干酪有良好的干酪味,质地紧密、光滑、富有弹性、颜色均匀,拉丝长度、融化性、起泡性好,与实验室制得的各指标相差不大,能满足披萨质量标准要求,适于大批量的生产,能够实现产品产业化、工业化.