正十六烷发酵产生柠檬酸的研究

通过试验筛选出产柠檬酸较高的菌种解脂复膜孢酵母１４６０菌和适宜培养基，确定了适宜的菌种起始浓度和底物浓度，证实谷氨酸对产生柠檬酸的促进作用。     

柠檬酸改性H-beta催化甲苯和叔丁醇烷基化

采用不同浓度的柠檬酸（HCA）对H-beta分子筛样品进行改性，通过XRD、SEM、TEM、FTIR、N₂物理吸脱附、NH₃-TPD及吡啶Py-IR等手段对改性分子筛进行了表征。实验结果表明，适宜浓度的柠檬酸改性不但没有破坏H-beta分子筛的骨架结构，而且在脱铝的同时兼具补铝功能。改性后的H-beta分子筛孔道更加畅通，虽然总酸量有所下降，但对烷基化有利的中强酸量和B酸含量却明显增加，催化活性增强。但柠檬酸浓度过高会脱除骨架铝，破坏晶格结构，导致催化活性降低。催化剂的甲苯叔丁基化活性评价表明，适宜的柠檬酸处理浓度为0.25mol/L。在0.25HCA/H-beta催化剂作用下，甲苯转化率为67.0%，对叔丁基甲苯的选择性高达80.4%。     

光助类Fenton-柠檬酸体系对甲基紫的脱色研究

以柠檬酸为活化剂,进行了类Fenton反应光解甲基紫的试验,研究了利用UV-H_2O_2-Fe~(3+)-柠檬酸体系对甲基紫进行脱色的各种影响因素。试验结果表明,Fe~(3+)、H_2O_2、柠檬酸浓度均能影响染料脱色,柠檬酸在反应过程中起到活化剂的作用。在甲基紫浓度为40mg/L时,其脱色的适宜条件为3%H_2O_2,100mg/L Fe~(3+),90mg/L柠檬酸,体系pH值约为3,其脱色率可达到80%以上。     

信息

天津柠檬酸走向世界据悉天津市工业微生物研究所有机酸研发中心又与一家大型跨国公司 ,成功签订了柠檬酸菌种及发酵工艺技术转让合同。至此 ,该所已先后向世界多家大型跨国公司转让了此类技术 ,使仅有 10名科研人员的研发中心 ,以其高科技每年创造数百万元的经济效益。柠檬酸是世界上应用广泛的有机酸中的一种 ,可以广泛应用于食品、石油开采、建筑、医药、化工等领域。柠檬酸发酵技术的核心是微生物菌种 ,近年来 ,该所在不断研发的基础上 ,率先在国内建立起了品种最多的 ,针对不同淀粉质原料发酵生产柠檬酸的菌种库。天津工业微生物研究所…     

应用海藻糖冻干保存幽门螺杆菌菌种

目的 应用海藻糖冻干保存幽门螺杆菌菌种。方法 筛选适宜浓度的海藻糖,用于冻干幽门螺杆菌标准株和临床分离株共18株,于冻干后逐年观察不同时期的细菌冻干后的存活率,并检定复苏菌种的形态及生化特性。结果 12.5％海藻糖冻干效果最好。保存3年后,复苏成功率近100％。不同时期的细菌均能耐受冻干,复苏菌种形态典型、生化特性无变异。结论 海藻糖是幽门螺杆菌适宜的冻干保护剂。     

柠檬酸对碳酸锰单分散粒子表面的电荷改性

用柠檬酸作为吸附剂,对MnCO3微粒表面电荷进行了改性.研究了柠檬酸溶液浓度、pH值和吸附温度对柠檬酸在MnCO3微粒表面吸附改性的影响.结果表明:随柠檬酸浓度的增加,MnCO3微粒表面对柠檬酸的吸附量逐渐增大,在柠檬酸浓度为1.0g/L附近达到吸附平衡;当pH值在6～11时,MnCO3颗粒表面ζ电位的绝对值均大于30...     

-乳酸的研究

从所选取的产l-乳酸的4株菌中筛选出一株性能优良、糖利用率和乳酸产量较高的菌种作为试验用菌种。对影响乳酸菌发酵大豆秸秆酶解物制备l-乳酸的因素进行了研究,影响大豆秸秆酶解液发酵的主要因素是菌种类型、底物糖浓度、接种量、温度及pH值。结果表明:干酪乳酸菌是较适宜的发酵菌种,较适宜的发酵条件为:发酵温度30℃,接种量10%,pH值5.5。随着底物糖含量的增加,乳酸产率相应增大,在实验范围内,乳酸菌发酵所产乳酸的产率达到80%。     

柠檬酸铁处理高浓度硫化氢炼厂酸性气的研究

通过选择柠檬酸配位剂和其它助剂，研究柠檬酸铁处理高浓度硫化氢炼厂酸性气体。实验分别考察了吸收剂Fe（Ⅲ）L浓度、溶液pH值、操作温度、硫化氢气体流量及传质方式对硫化氢吸收率的影响．确定柠檬酸铁脱硫体系适宜的反应条件。推荐最佳工艺参数为：柠檬酸铁浓度为0．6mol／L、pH8．5～9．0、操作温度40℃、配备合适的分布器、硫化氧气体流量以低于0．12m^3／h为宜。在最佳条件下H2S脱除率100％，反应中生成的硫磺可以通过过滤的方法除去。实验结果表明。利用柠檬酸铁处理含高浓度H2S的炼厂酸性气体具有工艺简单、脱除效率高、投资少、运行费用低等特点。     

柠檬酸铁处理高浓度硫化氢炼厂酸性气的研究

通过选择柠檬酸配位剂和其它助剂．研究柠檬酸铁处理高浓度硫化氢炼厂酸性气体。实验分别考察了吸收剂Fe（111）L浓度、溶液pH值、操作温度、硫化氢气体流量及传质方式对硫化氢吸收率的影响．确定柠檬酸铁脱硫体系适宜的反应条件。推荐最佳工艺参数为：柠檬酸铁浓度为0．6mol／L、pH8．5～9．0、操作温度40℃、配备合适的分布器、硫化氢气体流量以低于0．12m^3／h为宜。在最佳条件下HzS脱除率100％．反应中生成的硫磺可以通过过滤的方法除去。实验结果表明．利用柠檬酸铁处理含高浓度H2S的炼厂酸性气体具有工艺简单、脱除效率高、投资少、运行费用低等特点。     

柠檬酸发酵生产技术的几点探讨

国内生产柠檬酸的主要方法是以山芋干为淀粉原料(少数厂是以糖蜜为原料),以黑曲霉菌为生产菌种,经过深层液体发酵得到柠檬酸,再经过多道工序提取而制得柠檬酸产品。发酵是整个柠檬酸生产的一个重要部分,对整个生产效益有很大影响。     

Optimization of citric acid production by <Emphasis Type="Italic">Aspergillus niger</Emphasis> NRRL 567 grown in a column bioreactor

Citric acid production using Aspergillus niger NRRL 567 grown on peat moss has been optimized in a column bioreactor using a statistically based method. A 23 full factorial design with eight fermentation conditions was applied to evaluate significance on citric acid production and their interactions between variables, where the three independent variables evaluated were aeration rate, bed depth and temperature. Aeration rate and fermentation temperature were identified to be significant variables. Citric acid production markedly increases with aeration rate and fermentation temperature; however, the bed depth of solid substrate showed an insignificant effect on citric acid production. The optimum fermentation condition for citric acid production in a column bioreactor consisted of aeration rate of 0.84 vvm, bed depth of 22 cm and fermentation temperature of 32 °C. Under a given condition, a maximum citric acid production of 120.6 g/l was predicted and matched well with the experimental value of 123.9 g/kg.     

乳化液膜提取柠檬酸及其溶胀的研究

本文研究了采用Ｗ／Ｏ型乳化液膜提取水溶液中的柠檬酸，同时研究了柠檬酸提取过程中水的传质行为（乳液溶胀）。考察了表面活性剂、载体、反萃剂Ｎａ２ＣＯ３、柠檬酸浓度对柠檬酸传质和乳液溶胀的影响。实验结果表明：萃取率随载体和内相试剂浓度的增加而增加；当载体和初始柠檬酸浓度较高时，乳液更易于溶胀，由此得出了除渗透压造成的乳液溶胀外，溶质与载体形成的络合物也能促成乳液的溶胀。提出了分离浓缩柠檬酸的最佳乳液配方     

In‐line mixing for production of citric acid by Candida lipolytica grown on n‐paraffins

This study reports on the effects of internal fermenter and external in‐line agitation and fed‐batch mode of operation on citric acid production from Candida lipolytica using n‐paraffin as the carbon source. An optimum range of fermenter agitation speeds in the range 800–1000 rpm corresponding to Reynolds numbers of 50433–62947 (based on initial batch conditions) seemed to give the best balance between substrate utilization for biomass growth and citric acid production. Proof of concept evidence is presented that indicates that an external in‐line agitator could be used in place of high speed internal agitation to increase citric acid production. However, more work is required to optimize the external agitator concept. Application of multiple fed‐batch feedings can be used to extend the batch fermentation and increase final citric acid concentrations and product yield. Experiments were conducted implementing a three‐cycle fed‐batch process which increased overall citric acid yields to 0.8–1.0 g citric acid g^?1 n‐paraffin, approximately 200% improvement from those found in the normal batch process. The three‐cycle fed‐batch mode of operation also increased the final citric acid concentration to 42 g dm^?3 from about 6 g dm^?3 for normal batch operation. Increased citric acid concentrations in three‐cycle fed‐batch mode was achieved at longer fermentation times. Copyright © 2004 Society of Chemical Industry     

黑曲霉生产柠檬酸的控制论模型

黑曲霉发酵是工业生产柠檬酸的主要途径,研究该过程的动力学模型对更好地理解这一工业微生物的代谢机理有重要意义。基于黑曲霉(Aspergillus niger)柠檬酸发酵过程主要代谢途径的分析,构建了简化的碳代谢网络,建立了胞内物质和酶浓度的平衡模型。引入一阶闭环调节器模型描述发酵初期微生物酶系的建立过程。结合生物反应器模型,给出了重要宏观状态变量(如细胞物质浓度、基质浓度、产物浓度)和胞内酶浓度的动态仿真结果与实验值的对比。     

基于流变特性的动力学模型研究及在柠檬酸发酵过程的应用

研究了基于流变特性的动力学模型,并以实验统计数据为基础,通过对模型进行分析,推断了模型参数,同时将模型应用于柠檬酸发酵过程中。结果表明模型的拟合效果良好,从而表明所建立的模型基本符合柠檬酸发酵过程,这为显示流变特性对发酵代谢过程的影响提供了理论依据,也为实现柠檬酸发酵过程最优化提供必要条件。     

Forced modulation of biological processes: A review

Cell culture or biochemical processes utilizing free or immobilized cells or enzymes are candidates for periodic operation. Even though these processes are isothermal, inhibition frequently arises giving their kinetics a push-pull character of the Turing type so that excited states or multiplicity are observed. Modulation of an input such as a substrate or a nutrient concentration or the cell environment such as the pH can enhance the rates of biochemical reactions that are occurring. This possibility was realized by explorers of reactor periodic operation in the 1980s. However, the use of rotating disc biological filters for aerobic waste treatment precedes these activities by at least a decade. The biologically active slime on the disc surface is exposed alternately to air and to an aqueous media containing dissolved and/or suspended waste matter. Indeed, periodic variation of reactor volume in a CSTR, which is equivalent to periodic variation of space velocity, was explored in the early 1970s. The application of this was to activated sludge waste treatment. Periodic operation has been used to address the problem of plasmid loss in continuous fermenters to produce genetically altered microorganisms. A twofold increase in the concentration of plasmid bearing cells using square wave modulation of the dilution rate has been found in a simulation using a model validated by experimental data. These results are in agreement with other studies attempting to control species populations in chemostats. Improvement in the rate of fermentation of a substrate to form a metabolite has been addressed by modulation. It has been shown that the rate of xylose utilization by a yeast is affected by a periodic variation of pH. These were lowered, but the metabolite yield, ethanol, remained the same. With secondary metabolites associated with the non-growth period in fermentation, modulation of the growth-limiting substrate concentration fed to immobilized live cells resulted in significantly higher yields. Differences in the effect of cycling on primary and secondary metabolites has been observed in several biochemical systems, such as those used for penicillin and monoclonal antibody production or in citric acid fermentation.     

稀土元素对柠檬酸发酵的影响

研究了5种不同形态的稀土元素对黑曲霉Co827产柠檬酸的影响。结果表明,在发酵培养基中添加混合稀土（北方矿）、混合稀土（南方矿）、La3＋、Ce4＋使其浓度分别达到2.0、0.5、10、20mg/L时能提高产酸水平,而Nd3＋对发酵产酸的促进效果不明显。当任何一种稀土过量时都对产酸有抑制效应。     

紫外线诱变选育高产柠檬酸菌株及发酵条件研究

对1株初筛产柠檬酸黑曲霉进行紫外线诱变处理,并对选育的优势菌进行了发酵条件实验。研究结果表明,选育出的（Aspergillus niger）UV-5是一株优良高产菌株,该菌株的产酸率达到11.54%,比初始菌株（YZ-35）产酸率提高了24.41%;以红薯为发酵原料,在初始糖浓度15%、温度为35℃、起始pH值为5.5,转速140r·min-1、发酵84h的优化条件下,摇瓶发酵平均产酸率可达到13.15%。     

纤维素酶解液的柠檬酸发酵─—恒温发酵与周期变温发酵的比较

麦草经碱－氧－蒽醌蒸煮脱木素后得到纤维素。以纤维素酶酶解该纤维素后制得的纤维素酶解波为原料,在黑曲霉的作用下发酵制取柠檬酸。研究了恒温发酵及周期变温发酵过程,并对二者进行了比较。结果表明：周期变温可刺激菌体生长,在发酵初期有利于产酸。