响应面法优化紫绒丝膜菌产紫色素培养基

本实验目的在于优化液体发酵紫绒丝膜菌产紫色素的培养基。利用单因素方法筛选培养基中的影响色素产量的主要营养素,进而利用响应面法进行关键营养素配比的优化。单因素实验表明葡萄糖、KH2PO4、Mg SO4·7H2O的添加量对紫绒丝膜菌的色素的产量影响极为显著,其中葡萄糖表现出负效应,KH2PO4和Mg SO4·7H2O表现出正效应。选取3种显著因素进行响应面试验设计,经响应面优化后的最适培养基配方为葡萄糖21.48 g/L、KH2PO4 2.34 g/L,Mg SO4·7H2O 1.84 g/L、Ca Cl2 0.5 g/L,Fe Cl3·6H2O 0.5 g/L、Na Cl 0.5g/L、硫酸铵5 g/L,在此条件下最大响应色素产量值为1.05±0.07 g/L,与预测值0.99 g/L接近。紫绒丝膜菌液体发酵可大量产紫色素,该色素理化性质等值得进一步研究。     

统计学分析方法在普鲁兰发酵培养基优化中的应用

为了得到普鲁兰发酵的最佳培养基,在单因子实验的基础上,应用Plackett-Burman设计法对影响普鲁兰发酵的基本培养基组分中的关键因子进行了优选,并进一步采用响应面分析法(Response Surface Methodology,RSM)对影响普鲁兰产量的关键因素最佳水平范围作了深入的研究。实验结果表明:影响普鲁兰产量的关键因素为:葡萄糖、酵母粉和NaCl的浓度。通过RSM模型的拟合和推算得到在葡萄糖、酵母粉和NaCl质量浓度分别5.675、0.405、0.0815 g/dL时,此时模型预测发酵最佳的产量为32.071 44 g/L,验证值为32.16 g/L,预测值与验证值之间吻合较好,比原始培养基提高了约5倍。     

运用多元数学模型优化灰树花发酵培养基组成的研究

利用BoxBehnken3×3设计优化了影响灰树花深层发酵菌丝体和胞外多糖生产的主要培养基组成,碳源(葡萄糖)、氮源(蛋白胨)和无机盐(KH2PO4),响应面分析结果表明,各因素及其交互作用对响应值灰树花菌丝体和胞外多糖产量均存在显著的相关性。通过典型性分析,获得最大菌丝体量(17.61g/L)时,培养基组成为:葡萄糖45.2g/L,KH2PO42.97g/L,蛋白胨6.58g/L,MgSO4·7H2O1g/L和玉米浆15g/L;而获得最佳胞外多糖量(1.326g/L)时的培养基组成为:葡萄糖58.6g/L,KH2PO44.06g/L,蛋白胨3.79g/L,MgSO4·7H2O1g/L和玉米浆15g/L。与其他实验组的结果相比,优化后的灰树花菌丝体与胞外多糖的量都有较大的增加。15L发酵罐扩大培养的结果表明,在优化培养基组成的条件下,扩大培养后的菌丝体产量最大值达22.50g/L。     

黏红酵母产油脂培养基的响应面优化

利用单因素试验和响应面设计相结合,对黏红酵母产油脂培养基进行了优化。单因素试验得到初步发酵培养基成分为葡萄糖、蛋白胨、KH2PO4。经响应面优化发现,当发酵培养基中葡萄糖含量为73.40g/L,蛋白胨含量为1.06 g/L,KH2PO4含量为3.56 g/L时,油脂产量的理论预测值可达到3.49 g/L,比优化前提高了13%。气相分析其油脂组成,多不饱和脂肪酸质量分数为26.97%。然后又对高产菌株的发酵特性进行研究,在10 d时,生物量和油脂产量达到最高,此时达到发酵终点,生物量为47.98 g/L(菌体湿重),油脂产量达到7.81 g/L。     

海洋细菌Planococcus rifietoensis发酵产色素培养基的优化

在单因素的基础上,以Plackett-Burman(PB)设计结合响应面(RSM)分析法,对产色素海洋细菌Planococcus rifietoensis发酵培养基的8个营养成分配比进行优化。结果表明:培养基最佳碳氮源分别是葡萄糖和蛋白胨,葡萄糖、MgSO_4·7H_2O和酵母粉添加量显著影响色素的产量。Box-Benhnken设计分析确定最优培养基配方为:葡萄糖9.78 g/L,蛋白胨8.00 g/L,酵母粉2.05g/L,MgSO_4·7H_2O 8.17 g/L,Na_2HPO_40.1 g/L,FeSO_4·7H_2O 0.005 g/L,NaCl 10 g/L,CaCl_2 0.1 g/L,培养54 h,在此培养条件下,色素的OD值可达0.984,比优化前提高了245%。     

响应面法优化隐甲藻LS1057产二十二碳六烯酸发酵条件

为了提高一株隐甲藻藻株LS1057的二十二碳六烯酸产量,对发酵培养基进行了优化。采用Plackett-Burman实验设计法考察发酵培养基中各组分对二十二碳六烯酸产量的影响,结果表明:葡萄糖、酵母膏、KH2PO4的浓度对二十二碳六烯酸的产量影响显著。再用最陡爬坡路径逼近最大响应区域,并结合Box-Behnken实验设计和响应面分析法对3个显著因素进行回归分析,得到优化的发酵培养基组成:葡萄糖79.76g/L、酵母膏14.0g/L、KH2PO40.5g/L、海盐20.0g/L、MgSO4·7H2O 5.0g/L、KNO38.0g/L、FeSO4·7H2O 0.2g/L和M液(M液:V B10.6g/L,V B120.1mg/L)1%(V/V)。采用该法优化培养基,经摇瓶发酵实验供试藻株的二十二碳六烯酸产量达到了1.811g/L,较优化前提高了71.33%。利用70L发酵罐的分批补料发酵实验对优化后的结果做了进一步的验证,发酵结束后二十二碳六烯酸终产量为2.112g/L。实验结果表明经响应面法优化得到的发酵培养基利于隐甲藻LS1057发酵生产二十二碳六烯酸。     

响应面法优化α-葡萄糖苷酶发酵条件研究

采用Plackett-Burman(PB)分析法和响应面法(Response surface methodology,RSM)对臭曲霉产α-葡萄糖苷酶的发酵条件进行了优化。PB实验表明麦芽浸粉、KH2PO4、尿素、pH和接种量具有显著影响效应;然后利用最陡爬坡实验逼近最大响应区域,通过中心组合实验对影响产酶的主要因素进行研究,建立了影响因素与响应值之间的回归方程,并获得最佳发酵条件:麦芽浸粉38.13g/L,KH2PO47.88g/L,尿素0.91g/L,pH为5.76,接种量为9.63%。在此优化条件下发酵,α-葡萄糖苷酶产量提高了35%左右,达到1218.6U/mL。     

响应面法优化深黄被孢霉产油突变株的发酵培养基配方北大核心CSCD

为了优化深黄被孢霉突变株的发酵培养基,在单因素实验基础上,采用响应面法(RSM)对深黄被孢霉产油突变株发酵培养基配方进行优化。结果表明,深黄被孢霉产油突变株最佳发酵培养基配方为:葡萄糖90.29 g/L,酵母膏4.14 g/L,Mg SO40.96 g/L,KH2PO41.99 g/L,p H 6.0。在最佳条件下油脂产量为12.01 g/L,比优化前(6.22 g/L)提高了93.09%。     

响应面法优化深黄被孢霉产油突变株的发酵培养基配方

为了优化深黄被孢霉突变株的发酵培养基,在单因素实验基础上,采用响应面法(RSM)对深黄被孢霉产油突变株发酵培养基配方进行优化。结果表明,深黄被孢霉产油突变株最佳发酵培养基配方为:葡萄糖90.29 g/L,酵母膏4.14 g/L,Mg SO40.96 g/L,KH2PO41.99 g/L,p H 6.0。在最佳条件下油脂产量为12.01 g/L,比优化前(6.22 g/L)提高了93.09%。     

Sporidiobolus pararoseus WZ012产类胡萝卜素发酵条件的优化

以响应面方法对Sporidiobolus pararoseus WZ012产类胡萝卜素的摇瓶发酵条件进行了优化。在Plackett-Burman实验的基础上,利用中心组合设计研究了4个主要因素(葡萄糖、酵母膏、KH2PO4、接种量)对产类胡萝卜素的影响。结果表明,较高浓度的酵母膏和较大的接种量有助于类胡萝卜素的生产,而较高浓度的葡萄糖和KH2PO4有助于生物量的提高,生物量与类胡萝卜素产量之间没有必然的联系。优化得到的发酵培养基组成(g/L)为:葡萄糖60.23、酵母膏12.21、KH2PO41.68、接种量为8.38%。在此条件下红酵母产类胡萝卜素的最大产量为29.3mg/L,较优化前提高了54.1%。类胡萝卜素成分分析表明主要含有β-胡萝卜素、圆酵母素和红酵母红素这3种类胡萝卜素物质,其中β-胡萝卜素占62.5%。     

以诚信谋发展用服务建和谐

安徽八一纺织器材厂坐落在美丽的国家森林公园、国家风景名胜区天柱山麓.创建于1981年3月,从加工纺织用刷、络纱纸管等手工产品起步,逐渐滚动发展,不断积累壮大,从过去的粗加工产品发展到现在的高新技术产品,实现了质的飞跃,发展成为国内较大的纺织橡胶产品专业生产企业.主导产品有"潜阳"牌BYC系列棉纺牵伸用丁腈胶辊胶圈、罗拉轴承、并条芯轴等,以免处理胶管、微处理胶管、铝衬套胶管、高速并条胶管、花纹胶圈、纯化纤纺胶圈、高速导丝胶圈等高新技术产品为代表的优质产品群现已形成.各项经济指标逐年稳步上升,自1991年以来连续盈利15年,2005年实现销售收入超亿元,上缴利税近千万元,跃升为全国纺织机械器材行业50强骨干企业,先后荣获国家守合同重信用企业、安徽省明星企业、省扶贫工作先进集体、省先进企业、省重合同守信用先进单位、省文明单位、"AAA"资信企业、省高新技术企业、省诚信守法先进单位、省A级诚信纳税企业等荣誉称号.     

CdTe量子点同步荧光法测定番茄中链霉素残留

采用水热法制备巯基乙酸修饰的CdTe量子点,基于链霉素对CdTe量子点同步荧光强度的增强效应,建立一种测定链霉素含量的同步荧光法,并对测定条件如缓冲溶液pH值、量子点浓度和反应时间进行优化。样品经甲醇超声提取后,加入含1.0mL CdTe量子点溶液(3.5×10~(-5) mol/L)和1.0mL Tris—HCl缓冲溶液(pH=6.0)的溶液中,室温反应10min后,测定反应体系在345nm处的同步荧光强度(Δλ=230nm)。结果表明,链霉素浓度在5.0×10-7~1.0×10~(-5) mol/L时与体系相对同步荧光强度存在良好的线性关系,相关系数为0.999 7,检出限为1.0×10~(-8) mol/L。该方法操作简单、快速、灵敏度高,可用于番茄样品中链霉素残留的测定。     

Free radical formation by Lactobacillus acidophilus NCFM is enhanced by antioxidants and decreased by catalase

Lactobacillus acidophilus NCFM was found to increase the production of transient radicals during growth in a 1:1 mixture of brain heart infusion broth and de Man–Rogosa–Sharpe broth as detected by electron spin resonance (ESR) spectroscopy using spin trapping. During growth of L. acidophilus NCFM addition of quercetin, rutin or a whey protein hydrolysate, normally all with antioxidant activity, further increased formation of transient radicals. Such increase in the level of radicals in the growth medium did not have an adverse effect on the viability of L. acidophilus NCFM, but may be involved in inhibition of pathogenic bacteria by L. acidophilus. Catalase decreased the production of radicals without effect on the growth of the catalase-negative L. acidophilus NCFM, whereas superoxide dismutase had no effect on radical production, but hampered bacterial growth. The effect of catalase may be explained by non-radical removal of hydrogen peroxide otherwise being a precursor for hydroxyl radicals formed by transition metal catalysis. Metal ion concentrations decreased in the medium during bacterial growth, which may be the result of transport across bacterial membranes of redox active metal ions like iron and copper chelated by the antioxidant competing with reductive cleavage of hydrogen peroxide forming hydroxyl radicals. Antioxidants may accordingly promote probiotic effect of catalase-negative bacteria through increased formation of reactive oxygen species.     

微生物对果饮料质量影响研究

在果汁加工链上,任意一道工序都可能造成果饮料原料一水果的腐坏.从原料水果的采摘到成品果汁的销售这一系列过程中,产品质量降低导致在激烈市场竞争中公司名誉下降的结果,使制造商损失惨重.     

食用油压榨法和浸出法工艺的区别

编者按:8种食用植物油国家新标准的修订,是近两年来国内外油脂行业及农业、食品、轻工、进出口贸易、海关等部门十分关注的一件大事,经过两年多的努力,8种食用植物油国家新标准现已全部颁布,国家质检总局和国家标准化管理委员会已于2004年分别颁布实施了大豆油、花生油、棉籽油、葵花籽油、玉米油、米糠油、茶籽油等新标准,菜籽油新标准也将于2005年2月1日起实施,这是我国油脂界的一件大事,对新标准的具体实施过程中各个方面还存有这样那样的一些疑虑和认识上的偏差.本期<中国油脂>杂志刊出了我国著名油脂专家丁福祺教授级高级工程师对新标准中有关食用油压榨法与浸出法工艺的界定,特别强调了能上市的成品食用油,不管是用哪种工艺生产的,只要达到了国家标准规定的指标,都是可以放心食用的.同时,我们还约请食用植物油国家新标准的主要起草者--国家粮食储备局西安油脂科学研究设计院检测中心副主任薛雅琳高级工程师就最新颁布的菜籽油国家新标准中的条文和相关指标进行了详尽解释和说明.     

Iron Binding by Fiber is Influenced by Competing Minerals

Iron was bound by neutral (NDF) and acid (ADF) detergent fibers extracted from cooked pinto beans (Phaseolus vulgaris). Soluble iron (total iron minus bound iron) in the presence of NDF was increased from 13.11 ± 5.08 to 35.58 ± 9.20% and from 22.22 ± 164 to 29.98 ± 0.96% when 1.17 and 1.38 ppm (18.4 and 21.4 PM) of copper and zinc were added, respectively. In contrast, 0.93 μm (14.6 PM) of copper decreased the soluble iron from 61.02 ± 5.77 to 17.88 ± 4.5% in the presence of ADF. Neither magnesium or cobalt altered the amount of soluble iron in the presence of fiber. The change in soluble iron was directly proportional to the concentration of copper and zinc. The presence of two types of binding sites is proposed.     

Water Vapor Uptake by Fat-Free Apple Chips Decreased by Emulsifiers

The critical moisture sorption times of fat‐free apple chips varied from 29 min at 82% RH and 30 °C to over 24 h both at 34% RH, 20 °C and at 45% RH and 10 °C. Some emulsifiers added to the solution of carbohydrates used to treat apple slices before drying effectively decreased chip hygroscopicity. It was found that sodium stearoyl‐2‐lactate, sucrose esters, monoglycerides and their citric acid esters did not adversely affect flavor or texture of apple chips. During 3 h of exposure at 20 °C and 54% RH chips treated with these emulsifiers adsorbed from 14 to 25% less moisture than the untreated ones.     

超声辅助细胞转型的谷氨酸发酵工艺

为了进一步提高谷氨酸菌体细胞膜的通透性和谷氨酸产量,采用超声辅助谷氨酸发酵。通过单因素及正交实验研究,确定了最佳超声条件为超声时间50 s、振幅65%、间隔时间5 min,发酵起始,即开始超声处理至发酵8 h,结束超声。在最佳超声条件下进行谷氨酸发酵,菌体OD(600 nm)值为82. 5,提高13. 8%,谷氨酸产量为168 g/L,提高11. 3%,糖酸转化率为68. 2%,提高4. 3%,菌体转型时间由4 h提前至2 h。超声辅助谷氨酸发酵能够达到较好的效果,使发酵过程更加稳定。     

Neutral-sugar determination by HPAEC-PAD to characterise polysaccharide degradation by colonic bacteria

 In vitro methods are widely used to characterise dietary fibre fermentability in the human hind gut. The activity of faecal bacteria can be followed by measuring fermentation products and substrate degradation. This paper describes a method for establishing neutral-sugar profiles by HPAEC-PAD during in vitro fermentation studies. Freeze-dried fermentation residues are hydrolysed with H₂SO₄, and the monomers are separated on an anion-exchange column using a reverse NaOH gradient. Sulphate ions are removed from hydrolysates on-line with a special ion-exchange guard column. 2-D-deoxyribose is used as internal standard for quantification. A method for separating all neutral sugars that typically occur in dietary fibre is given. Possibilities for enhancing the resolution for other purposes are suggested. Compared to GC the described method is particularly attractive for routine analyses. Data relating to the decreasing levels of neutral sugars in fermentation residues of oat bran fractions that differ in their mixed-linked β-glucan content are given and degradation patterns of the polysaccharides present in these substrates are discussed. Received: 26 February 1997