响应面法优化嗜热链球菌增殖培养基

目的 为了降低嗜热链球菌工业化生产成本,提高其发酵活菌数,对嗜热链球菌原始培养基的成分进行了响应面优化.方法 利用Design-Expert软件首先采用Plackett-Burman试验设计筛选出了影响嗜热链球菌生长的显著因子,再依据响应面法设计试验,得到嗜热链球菌的优化培养基配比.结果 乳糖、酵母粉和L-半胱氨酸为嗜热链球菌生长的显著性因子;优化后培养基配比由结果分析可知,当活菌数达到最大值时,即:乳糖的浓度为3.6％,酵母粉的浓度为1.74％,L-半胱氨酸的浓度为1.1％,牛肉蛋白胨1％,酪胨1％,KH2PO4 0.20％,Na2 HPO40.20％,叶温-80 0.1％活菌数为最高2.34×109 CFU/mL.结论 采用响应面分析法优化的培养基较经典TPY培养基活菌数提高了近2～3倍.     

粘性嗜热链球菌ST-1产胞外多糖发酵条件优化

应用响应面法对一株粘性嗜热链球菌ST-1的产胞外多糖的发酵条件进行了优化.根据单因素的实验结果,选取接种量,发酵温度,发酵时间作为考察因素,以胞外多糖的产量作为响应值,利用Box-Behnken实验设计方法,建立了胞外多糖产量与三个考察因素之间的回归方程并得到最佳发酵条件为:接种量5%,发酵时间14 h,发酵温度42℃...     

一株嗜热链球菌产多糖条件的优化

使用单因素和正交试验设计相结合的方法对培养基配方及培养条件进行优化提高嗜热链球菌AR333的胞外多糖(exopolysaccharides,EPS)产量.获得最佳培养基配方为:脱脂乳粉15％(w/v)、半乳糖1％ (w/v)、大豆蛋白胨0.5％ (w/v)、磷酸氢二钾0.1％ (w/v).最佳培养条件为:接种量3％,40℃,初始pH6.5,发酵时间16 h.优化后嗜热链球菌AR333的EPS产量可达256.97mg/L,比优化前的产量提高了3.6倍.     

应用响应面法优化嗜热脂肪土芽孢杆菌培养基

目的：筛选并优化嗜热脂肪芽孢杆菌CHB1液体发酵培养基。方法：通过Plackett-Burman试验和响应面分析方法,确定培养基的主要影响因素和最佳浓度。结果：利用SAS软件进行分析,确定对响应值影响最大的3个因素为豆粕、酵母粉、K2HPO4。最佳培养基组成为0.51%、豆粕浓度为0.425%、K2HPO4浓度为0.994%。根据模型预测得到的理论最大菌数为2.94×10^8cfu。在初始条件下实验,菌数为2.40×10^8cfu,在优化的最佳培养基条件下,实际的菌数为3.06×10^8cfu。菌数比优化前提高了27.3%。试验值与预测值的误差为4.08%。结论：实验值与模型预测值拟合良好。     

嗜热链球菌培养条件的研究

将嗜热链球菌（Ｓｔｒｅｐｔｏｃｏｃｃｕｓｔｈｅｒｍｏｐｈｉｌｕｓ）在６种固体培养基及７种液体培养基中的生长情况进行了比较,结果表明,改良ＩＲＩＥ固体培养基上的溶钙圈大,活菌数最多;在７种液体培养基中亦以改良ＩＲＩＥ的ＯＤ值最高,活菌最多,达８×１０^８／ｍｌ以上。以此培养基做生长曲线,该菌的平衡期为１２～１６ｈ。     

嗜热链球菌高密度发酵过程的优化方案探讨

本研究介绍了嗜热链球菌（Streptococcus thermophilus）高密度发酵过程的优化方案。首先从培养基优化方案入手,讨论了单因素法与正交实验法在培养基优化过程中的利弊。第二,介绍了培养条件以及发酵过程的优化,包括pH、培养温度、搅拌转速、接种量和培养时间。第三,介绍了菌体的后处理过程,包括降温处理、超声解链、离心冻干。     

制备高效大肠杆菌电转化感受态细胞和电转化条件的研究

旨在建立一种高效大肠杆菌电转化感受态细胞的制备方法,研究了摇瓶装液量,菌体生长阶段,转化电场强度,转化后复苏时间以及感受态细胞存放时间等对转化效率的影响.结果表明,基液量为400 mL/2L,菌体在OD600值为0.452时收集所制备的感受态细胞,在电场强度12.5 kV/cm条件下电击5 ms,转化后复苏时间2h,转化效率可达到1010CFU/μg DNA.此条件下制备的感受态细胞转化效率高,质量稳定,重复性好.     

嗜酸乳杆菌与嗜热链球菌共发酵互生机理的研究

目的:对嗜酸乳杆菌和嗜热链球菌共发酵时两者的互生作用机理进行研究。方法:以质量浓度100gL脱脂乳为培养基,将嗜酸乳杆菌主要代谢产物—氨基酸,如赖氨酸、精氨酸、缬氨酸分别以0.0083mgml、0.0036mgml、0.0053mgml的量加入含嗜热链球菌脱脂乳培养基中,40℃培养,测定凝乳时间;将嗜热链球菌的代谢产物-乳酸、甲酸分别为0.1332mgml和0.075mgml的量加入含嗜酸乳杆菌脱脂乳培养基中,37℃培养,测定其发酵乳的凝乳时间。结果:嗜热链球菌发酵乳凝乳时间由12h缩短到4h,pH为4.52～4.62,吉尔涅尔度为54.23～64.74°T;嗜酸乳杆菌发酵乳的凝乳时间由16h缩短为5h,pH为4.61～4.65;且嗜酸乳杆菌在CO2环境中发酵时,发酵时间明显缩短。结论:嗜酸乳杆菌和嗜热链球菌共发酵时具有互生关系。     

响应面法优化酿酒酵母产油脂条件

运用响应面法对酿酒酵母(Saccharomyces cerevisiae)产油脂以及发酵条件优化进行了研究。首先根据单因素实验结果,利用Plackett-Burman设计对影响其产油脂相关因素进行评估并筛选出具有显著效应的3个因素:柠檬酸,CaCl2和初始pH值。接着用最陡爬坡试验逼近以上3个因子的最大响应区域后,采用Box-Behnken设计以及响应面分析法,确定其优化后发酵条件为(w/v):葡萄糖15%,蛋白胨0.2%,酵母浸粉0.4%,柠檬酸0.471%,MgSO4·7H2O0.1%,ZnSO4·7H2O0.2%,CaCl20.025%,FeSO4·7H2O0.005%,初始pH值为6.74,180r/min,30°C培养96h。优化后的油脂产率(干重)达到14.55%,比在种子培养基中油脂产率4.76%提高了2倍左右。     

嗜热厌氧乙醇菌JW200转化条件的研究

摘要 嗜热厌氧乙醇菌遗传转化系统的缺少,制约了对该菌理论基础和应用领域的进一步研究。利用聚乙二醇（PEG6000）转化和电转化技术国际首次实现了嗜热厌氧乙醇菌JW200外源基因的导入。PEG转化效率很低,因此选择对电转化条件进行优化,转化效率从4±3.2个转化子/μg质粒DNA提高到50±7.4个转化子/μg质粒DNA。实验表明获得较高的转化效率的必要条件是在细胞密度为OD660 0.2时添加甘氨酸与蔗糖后继续培养2h以及细胞在电击前的收集与洗涤保持低温。本研究为利用基因工程手段改造嗜热厌氧乙醇菌和从分子水平研究胞内乙醇代谢途径奠定了基础。     

Optimization of lipase-catalyzed synthesis of acetylated EGCG by response surface methodology

(−)-Epigallocatechin-3-O-gallate (EGCG) acetylated derivatives, which can be widely used as a natural antioxidant in both lipid containing food and cosmetic applications, were prepared by lipase catalyzed acylation of EGCG with vinyl acetate. Response surface methodology (RSM) and 5-level-4-factor central composite rotatable design (CCRD) were employed to evaluate the effects of synthesis parameters, such as reaction time (6–10 h), temperature (30–50 °C), enzyme amount (1.5–2.5% (w/w) of substrate), and substrate molar ratio of EGCG to vinyl acetate (0.5–1.5) on conversion of EGCG. By using multiple regression analysis, the experimental data were fitted to a second order polynomial model. The most suitable combination of variables was 40 °C, 2.12%, 10 h and 1.13 for the reaction temperature, the enzyme amount, the reaction time, and EGCG/vinyl acetate mole ratio, respectively. At these optimal conditions, the conversion yield reached 87.37%. The presence of mono-, di- and tri-acetylated derivatives in acetylated EGCG was confirmed by LC–MS-MS and identified as 5″-O-acetyl-EGCG, 3″, 5″-2-O-acetyl-EGCG and 5′, 3″, 5″-3-O-acetyl-EGCG by NMR.     

响应面法优化粉被虫草中虫草素的提取工艺

【背景】粉被虫草是民间常用药用真菌,具有抗辐射等多种药理作用,虫草素是其重要的活性物质。【目的】探究粉被虫草中提取虫草素的影响因素,为制取虫草素提供参考。【方法】以虫草素得率为指标,用响应面法优化超声提取工艺。分别考察超声时间、液料比和超声功率对提取效率的影响,在单因素实验基础上进行3因素3水平的响应面分析实验。【结果】最优提取条件为超声时间606 s、液料比45.9:1、超声功率400 W,在此条件下虫草素得率为6.136 mg/g,与模型预测值接近,方程拟合良好。【结论】首次对粉被虫草中虫草素的提取条件进行了研究,将对制取虫草素提供参考,有利于粉被虫草的深度开发利用。     

响应面分析法优化耐高温假黄色单胞菌硫氧化性能

【目的】采用响应面分析法对耐高温假黄色单胞菌的硫氧化性能进行优化。【方法】利用Plackett-Burman试验筛选影响菌株硫氧化性能的关键因子。通过最陡爬坡试验逼近最佳值区域,确定响应面试验中心轴,利用Box-Behnken设计和响应面分析法获得关键因素的最佳浓度。采用经典的改良硫酸钡比浊法测定硫酸根含量。【结果】牛肉膏、麦芽糖、镁离子(Mg~(2+))3个因素是影响菌株硫氧化性能的关键因素。响应面分析表明牛肉膏和镁离子的交互作用对硫酸根转化率的影响最大,优化后的结果为:麦芽糖(%)=0.07,牛肉膏(%)=0.11,Mg~(2+)(%)=0.04时,模型有最大值。模型的F值为52.60(P0.000 1),相关系数R2=0.980 2,说明该二次方程是显著的,该模型在整个回归区域内的拟合较好。经模拟堆肥试验验证该菌株可以有效增加堆肥中硫酸根含量。【结论】该模型可用于分析和预测耐高温假黄色单胞菌优化培养基配方,经优化后该菌株硫氧化性能大幅提升,硫酸根转化率由36.89%提高到80%以上,加入堆肥后与基础发酵条件下菌液相比更加有效增加了堆肥中SO_4~(2-)的含量,具有较好的应用前景。     

Transformation of group A streptococci by electroporation

Abstract The introduction, via electroporation, of free plasmid DNA into three strains of Streptococcus pyogenes is described. The method is very simple and rapid and efficiencies vary from 1 × 10³ to 4 × 10⁴ per μg of DNA. The method was also used to introduce an integrative plasmid and transformants were obtained, albeit at a somewhat lower frequency (2 × 10²). Some of the plasmids used in this study are derivatives of the Lactococcus lactis subsp. cremoris Wg2 plasmid pWV01. These broad host range vectors replicate in Gram-positives as well as Gram-negatives (viz. Escherichia coli ). Here we show that they also replicate in S. pyogenes and S. sanguis .     

Isolation and characterisation of promoter regions from Streptococcus thermophilus

Abstract Four promoter regions required for the expression of a promoterless antibiotic resistance gene ( cat194 ) in Streptococcus thermophilus were isolated by random chromosomal cloning experiments. These were shown to be functional in vivo, and their sequences were determined. Each region expressed different amounts of Cat protein as determined by enzyme activities. One region, STP10, was found to contain the 5' coding region of the large ribosomal subunit protein L20.     

响应面法优化细菌EHB01对铜绿微囊藻(Microcystis aeruginosa)的溶藻条件

【背景】水体富营养化导致的蓝藻水华对淡水资源造成了严重污染。利用环境友好型的溶藻菌可有效控制蓝藻的生长,是防治蓝藻水华形成的有效途径之一。【目的】优化溶藻细菌EHB01对铜绿微囊藻(Microcystis aeruginosa)的溶藻条件,以期为治理蓝藻水华污染提供高效的溶藻菌制剂。【方法】采用单因素试验对溶藻的发酵液浓度、温度、光照以及C:N和N:P进行分析,并对溶藻细菌EHB01发酵液的碳源、氮源和p H进行优化。基于单因素试验,选用中心组合试验设计(central composite design,CCD)确定关键因子的最佳数量水平,并以Desig-Expert 8.0.5进行回归分析,通过响应面分析获得溶藻效果最佳的参数。【结果】发酵液浓度对溶藻率的影响表现为持续上升;温度对溶藻率表现为先上升后下降;而光照、C:N和N:P均对细菌EHB01发酵液溶藻率的影响表现为先降低后上升的趋势。溶藻细菌EHB01发酵液所需的最佳碳源为蔗糖,氮源为硝酸钾,pH为7.5,优化条件下溶藻率达86.97%,与优化之前相比提高了21.72%。【结论】采用响应面法优化得出溶藻细菌EHB01发酵液最优的...     

Optimization of calcium pectinate gel beads for sustained-release of catechin using response surface methodology

Response surface methodology was used to optimize bead preparation conditions, including CaCl₂ concentration (X₁), hydroxypropylmethylcellulose concentration (X₂), and bead-hardening time (X₃), for the sustained-release of catechin from the calcium pectinate gel beads reinforced with liposomes and hydroxypropylmethylcellulose into simulated gastric fluid (SGF) and intestinal fluid (SIF). The optimized values of X₁, X₂, and X₃ were found to be 5.82%, 0.08%, and 10.29 min, respectively. The beads prepared according to the optimized conditions released only about half of the entrapped catechin into SGF while most of the entrapped catechin was released into SIF after 24 h incubation.