Effects of Fed-batch and Nitrogen-deficient Culture on Lipid Yield of Chlorella sp.

[Objective] This study was to realize high-density culture of Chlorella sp. as well as the culture with high lipid yield. [Method] Through analyzing the growth curve of Chlorella sp. cells, dextrose consumption curve, change curves of pH and dissolved oxygen, a fed-batch culture was conducted, followed by a nitrogen-deficient culture aiming at accumulating the lipids in Chlorella sp. cells when a high density of Chlorella sp. cells was obtained. [Result] After four batches of feeding were pro- vided, the biomass of Chlorella sp. reached up to 65.25 g/L, and the lipid content increased from 42.75% to 63.82% in Chlorella sp. cells, with the yield of 43.37 g/L in the following 12 hours of nitrogen-deficient culture. [Conclusion] Reasonable fed- batch can significantly improve the biomass of Chlorella sp., and the nitrogen-defi- cient culture further raises the lipid yield of Chlorella sp.

Process Control for Production of Human-like Collagen in Fed-batch Culture of Escherichia coli BL 21

Recombinant E. coli BL 21 was cultivated in high cell density to produce human-like collagen. The effects of the feeding of nitrogen source, controlled by an auto on/off-feeding mode with two different cycles of 0.5min and 4min intervals, oxygen-enrichment methods and inducement strength on the cell yield and human-like collagen production were investigated. The studies showed that nitrogen source feeding in fast cycle could result in higher human-like collagen production than that in slow cycle; and the feedback regulation of glucose, increase of the pressure of fermentation bioreactor, and supply of oxygen-enriched air could all increase cell yield and human-like collagen production. The effects of inducement strength on protein expression were found important. When OD600 reached 90-100, the cultivation temperature was increased to 42℃ to begin induction for 2-3 h, and then shifted to 39℃ for 5-6h induction, the cell density and human-like collagen production could reach 96g·L-1 [DCW (dry cell mass)] and 19.8% (g·g-1 DCW) respectively.

Batch and fed-batch production of butyric acid by Clostridium butyricum ZJUCB

The production of butyric acid by Clostridium butyricum ZJUCB at various pH values was investigated. In order to study the effect of pH on cell growth, butyric acid biosynthesis and reducing sugar consumption, different cultivation pH values ranging from 6.0 to 7.5 were evaluated in 5-L bioreactor. In controlled pH batch fermentation, the optimum pH for cell growth and butyric acid production was 6.5 with a cell yield of 3.65 g/L and butyric acid yield of 12.25 g/L. Based on these results, this study then compared batch and fed-batch fermentation of butyric acid production at pH 6.5. Maximum value (16.74 g/L) of butyric acid concentration was obtained in fed-batch fermentation compared to 12.25 g/L in batch fermentation. It was concluded that culti- vation under fed-batch fermentation mode could enhance butyric acid production significantly (P<0.01) by C. butyricum ZJUCB.

Run-to-run Optimization for Fed-batch Fermentation Process with Swarm Energy Conservation Particle Swarm Optimization Algorithm

An iterative optimization strategy for fed-batch fermentation process is presented by combining a run-to-run optimization with swarm energy conservation particle swarm optimization (SEC-PSO). SEC-PSO, which is designed with the concept of energy conservation, can solve the problem of premature convergence frequently appeared in standard PSO algorithm by partitioning its population into several sub-swarms according to the energy of the swarm and is used in the optimization strategy for parameter identification and operation condition optimization. The run-to-run optimization exploits the repetitive nature of fed-batch processes in order to deal with the optimal problems of fed-batch fermentation process with inaccurate process model and unsteady process state. The kinetic model parameters, used in the operation condition optimization of the next run, are adjusted by calculating time-series data obtained from real fed-batch process in the run-to-run optimization. The simulation results show that the strategy can adjust its kinetic model dynamically and overcome the instability of fed-batch process effectively. Run-to-run strategy with SEC-PSO provides an effective method for optimization of fed-batch fermentation process.

Production of Ammonium Lactate by Fed-batch Fermentation of Rhizopus oryzaefrom Corncob Hydrolysate

L-(+)-Lactic acid production from corncob hydrolysate as a cheap carbohydrate source by fed-batch fermentation of Rhizopus oryzaeHZS6 was studied. After 96 h of fermentation in a 5 L fermentor, the final concentration of ammonium L-(+)-lactate, average productivity(based on initial xylose concentration) and maximum dry cell weight were 132.4 g/L, 1.38 g/(L·h), and 8.9 g/L respectively. The optical purity of L-(+)-lactate was 98.8%.

Improved 5-Aminolevulinic Acid Production with Recombinant Escherichia coli by a Short-term Dissolved Oxygen Shock in Fed-batch Fermentation

5-Aminolevulinic acid （ALA） is a common precursor for tetrapyrrole compounds in all kinds of organ isms and has wide applications in agriculture and medicines. In this study, a new strategy, i.e. short-term dissolved oxygen （DO） shock during aerobic fermentation, was introduced to produce 5-aminolevulinic acid with a recombi-nant E. coli. Effects of duration time of DO shock operation on plasmid concentration, intracellular ALA synthase （ALAS） activity and ALA production were investigated in Erlenmeyer shake flasks. The results indicated that both ALAS activity and ALA yield were enhanced in an anaerobic operation of 45 rain in the early exponential phase during fermentation, while they decreased when the anaerobic operation time was further increased to 60 rain. The DO shock protocol was confirmed with the fed-batch fermentation in a 15 L fermenter and the ALA production achieved 9.4 g.L-1 （72 mmol.L-1）, which is the highest yield in the fermentation broth reported up to now.

Strategies for Optimizing Feed Rate of Fed-Batch Yeast Fermentation by Fuzzy-Neural Network

In this paper,a novel fuzzy neural network model,in which an adjustable fuzzy sub-space was designed by uniform design,has been established and used in fed-batch yeast fermentationas an example.A brand-new optimization sub-network with special structure has been built andgenetic algorithm,guaranteeing the optimization in overall space,is introduced for the feed rateoptimization.On the basis of the model network,the optimal substrate concentration and theoptimal amount of fed-batch at different periods have been studied,aided with the optimizationnetwork and the genetic algorithm separately.The above results can be used as a basis for theestablishment of a fuzzy neural network controller.

NonliNonlinear GPC with In-place Trained RLS-SVM Model for DOC Control in a Fed-batch Bioreactor

In this study, Saccharomyces cerevisiae (baker's yeast) was produced in a fed-batch bioreactor at the optimal dissolved oxygen concentration (DOC) and growth medium temperature. However, it is very difficult to control the DOC using conventional controllers because of the poorly understood and constantly changing dynamics of the bioprocess. A generalized predictive controller (GPC) based on a nonlinear autoregressive integrated moving average exogenous (NARIMAX) model is presented to stabilize the DOC by manipulation of air flow rate. The NARIMAX model is built by an improved recursive least-squares support vector machine, which is trained by an in-place computation scheme and avoids the computation of the inverse of a large matrix and memory reallocation. The proposed nonlinear GPC algorithm requires little preliminary knowledge of the fermentation process, and directly obtains the nonlinear model in matrix form by using iterative multiple modeling instead of linearization at each sampling period. By application of an on-line bioreactor control, experimental results demonstrate the robustness, effectiveness and advantages of the new controller.

Remote Control of Fed-Batch Fermentation Systems

Bioreactor operation requires continuous monitoring of fermentation parameters and real-time control over bioreactor devices. Remote monitoring and control of the bioreactor＇s computer via the Internet avoids the necessity of personnel being continually onsite during operation. A two liter Sartorius-stedim Biostat~ A Plus fermentation system was networked and interfaced with the commercial software from GoToMyPC to allow remote control of the fermentation system utilizing the internet. The fermentation vessel was equipped with hardware calibrated for monitoring and controlling culture parameters during experimentations. The uniform resource locator controlled night-vision web camera allowed continuous monitoring of the glass fermentation vessel during the day and at night. The main window screen of the laboratory computer can be securely accessed from any portable device （i.e. laptop） capable of establishing an Internet connection and executing the commercial software from GoToMyPC. The secured internet protocol address, provided by GoToMyPC, assures that the system can only be controlled by authorized users who have been given access to the account. This interface permits the remote control of the Biostat A Plus fermentation system and possibly other automated or potentially automated culturing systems at the convenience of the user（s）.

On-line Scheduling Algorithm for Penicillin Fed-batch Fermentation

An on-line scheduling algorithm to maximize gross profit of penicillin fed-batch fermentation is proposed. According to the on-line classification method, fed-batch fermentation batches are classified into three categories. Using the scheduling strategy, the optimal termination sequence of batches is obtained. Pseudo on-line simulations for testing the proposed algorithm with the data from industrial scale penicillin fermentation are carried out.

Isolation of enriched-yielders and fed-batch production of alkaline protease from the newly isolated <i>Bacillus</i>sp. BHA

An alkalophilc and thermophilic Bacillus sp. BHA that produced a thermostable alkaline protease was isolated from decaying protein substrates. The isolate was found to grow in pH range 7 - 11 with an optimum pH 9.0 and temperature up to 55℃. The activity of alkaline protease of Bacillus sp. BHA (68.98 APU/ml) was found higher than the standard strains of Bacillus amyloliquefaciens MTCC 610 (8.98 APU/ml) and Bacillus subtilis MTCC 8349 (12.14 APU/ml, used in this study, and was comparable (68.98 APU/ml, equivalent to 30.38 APU/mg) to the activity of the commercially produced standard protease procured from Novo Nordisk, Denmark (30.35 APU/mg). Hence, the proteolytic activity produced by this isolate was further investigated in batch and fed-batch process. Sucrose was the best carbon source for the production of protease activity by that isolate. Different organic nitrogen sources (casein, peptone and beef extract) at 1% (w/v) with varying levels of sucrose (1% - 4% w/v) initially repress enzyme synthesis. The duration and extent of repression decreased with increased concentration of sucrose. Maximum protease activity was found in basal medium with 4% (w/v) sucrose and 1% (w/v) yeast extract. Yeast-extract was thought to be an inducer of enzyme synthesis. Further, the basal medium was unique with respect to the enzyme production, as protease production was growth associated with the peak enzyme production being detected at the time of maximum growth. Interestingly, a rise in 34.2% (104.86 APU/ml) of protease activity was detected at incubation temperature of 50℃ and when culture filtrate was assayed at 60℃, signifying a high temperature stability of the produced protease by this isolate. Additional studies on the enzyme characterization were resulted in recognition of highly significant properties of the activity towards casein at pH 9.0 and stability at high temperature with retention of 96% the enzyme activity at 60℃. The parametric study under feed intervals had enabled improvement in the maximum protease activities attainable from batch cultures in excess of 21.78% and 26.32% via two feeding strategies. A small continual increase in enzyme activity (132.46 APU/ml during 24 h - 120 h) and enhancement in protease production in excess of 36.84% was observed by fed-batch process than the batch experiment.

微生物培养基质量控制技术和标准

微生物培养基的酸碱度、凝胶强度和选择性等直接影响到培养基的质量,在理化试验方法中采用连接可渗透陶器型液体接头的电极和平头电极或者连接微型探头的电极可分别测定液体和固体培养基的pH值,而采用Gelometer和theLFRATextureAnalyser可测定固体培养基的凝胶强度。在微生物学方法中固体培养基采用倾注平板法、涂布法、划线法(半定量法)、改良的Miles-Misra法等测定生长情况,液体培养基采用稀释法测定生长率,用目标菌和杂菌的混合菌株评价选择性增菌培养基的选择性,利用OD值评价液体培养基生长率等。ICFMH(国际食品微生物学和卫生学委员会培养基工作组)、ISO、FDA以及我国卫生部等相继制定了培养基质量控制的标准,但目前还没有一个系统的适合我国国情的培养基质量控制国家标准,以致各相关单位采用的标准不一致,所以制定培养基质量控制国家标准非常关键。

三种桃砧木茎尖培养技术的研究

以砧选1号、东溪小仙桃、毛桃茎尖为试验材料进行组织培养,研究不同消毒处理、基本培养基、植物激素的种类和浓度对桃砧木茎尖初代、继代和生根培养的影响。结果表明:初代培养中最适宜消毒方法为75%酒精30 s和0.1%升汞(HgCl2)3 min,植株下部外植体成活率较高;MS(6-BA 0.5 mg·L-1,IBA 0.2 mg·L-1)为东溪小仙桃和砧选1号最佳初代培养基,成活率分别为73.33%和76.67%;适合毛桃和砧选1号的继代培养基为MS(6-BA 1.5 mg·L-1,IBA 0.2 mg·L-1),适合东溪小仙桃的继代培养基MS(6-BA 2.0 mg·L-1,IBA 0.5 mg·L-1);1/2MS基本培养基对嫩梢生根诱导效果最好,适宜毛桃和砧选1号的生根培养基为1/2MS(IBA 1.0 mg·L-1),适宜东溪小仙桃的为1/2MS(IBA 0.5 mg·L-1)。

面向科技融合的文化创意产业协同创新机制研究

针对文化创意产业与科技融合中存在的问题进行了研究,探索了在文化产业新内涵以及网络与信息化的信用保障体系下,对文化产业集群中的多领域、多单位主体以及人才之间建立起有效的信息互动共享与交流机制;依托西安交通大学文化创意产业研究中心的建设,力图搭建文化产业"产学研"与科技文化产业融合的合作桥梁,探求建立有效的文化创意协同创新服务机制和体系。

自然界中难分离培养微生物的分离和应用

采用在分离培养基中添加自然来源的抽提液,或加入一些特殊化合物,使其中处于Viable but non-culturable(VBNC)状态的微生物恢复其生长繁殖能力,从而得到分离。实验结果发现甜菜碱、丙酮酸钠、SOD以及过氧化氢酶可使分离到的微生物种类及菌落总数明显增加。还采用固液结合的方法来分离那些在普通平板培养基上不能形成肉眼可见菌落的那些微小菌落的微生物。采用这几种方法从4份土壤样品中共分离得到52株放线菌,103株细菌,17株真菌。对其中的放线菌和真菌进行了生物活性的测定,得到多株具有抗菌活性的微生物,经过多次复筛的平均阳性率为4．325％,略高于用常规方法分离得到的微生物。因此证明有效的分离方法将为今后微生物药物的筛选和药用微生物菌种的保藏提供更丰富的来源。

小球藻对养殖废水中N、P的去除研究

针对工厂化对虾养殖废水处理进行了初步研究,通过模拟试验进行小球藻N、P去除能力的探索。结果表明:被试藻类在水体中生长良好,小球藻能很好地去除水体的N、P,培养4 d后,水体中NH4-N的去除率达到80%以上、PO4-P的去除率达到85%以上;在适宜的温度、光照、pH值条件下,最适合小球藻生长的N/P值为8,小球藻的4 d增长量可以达到初始量的10倍。

WHO生存质量评估简表的等价性评价

目的评价WHO生存质量评估简表(WHOQOL-BREF)在13个国家的等价性。方法采用多组验证性因子分析方法,对世界卫生组织生存质量研究小组提供的13个国家的数据进行分析,评价WHOQOL-BREF不同国家的等价性。结果各个国家的各个领域的Cronbachα系数均大于0·7,分布在0·7至0·88之间。除了英国和挪威之外,其它国家的社会关系领域的Cronbachα系数均大于0·65。采用根据世界卫生组织生存质量研究小组研制量表时构建的四因子模型对数据分别进行拟合,拟合优度指数(CFI)均大于0·8,其中德国、西班牙和美国的拟合优度指数大于0·9。多组验证性因子分析发现模型拟合尚可,CFI等于0·88,各个国家的因子负荷不全相等,因子负荷的轮廓相似。结论WHOQOL-BREF在13个国家具有相同的因子结构,且有等价性。

PK15、Vero、BHK、CEF细胞增殖猪伪狂犬病病毒的比较

为了研究伪狂犬病病毒,从而预防该病的发生。[方法]对PK15、Vero、BHK、CEF 4种细胞增殖猪伪狂犬病病毒后细胞病变进行比较,并对4种细胞增殖的PRV分别进行毒价测定。[结果]4种细胞增殖PRV毒价分别为:PK15细胞107.15TCID50/ml;BHK细胞107.00TCID50/ml;Vero细胞106.96TCID50/ml;CEF细胞106.70TCID50/ml。[结论]PRV毒株在不同细胞上增殖CPE表现不同,毒价也存在差异。

不同有机酸对断奶仔猪肠道厌氧培养微生物菌群的影响

【目的】建立仔猪肠道微生物菌群调控的离体模型,并研究有机酸对断奶仔猪肠道微生物菌群的影响.【方法】每次试验选取2头40日龄杜×（长×大）仔猪,屠宰后取其空肠和回肠混合食糜,按照每管300μL分装于2 m L离心管,分别添加30 mmol·L^-1不同有机酸（甲酸、乙酸、丙酸、丁酸、乳酸、富马酸、柠檬酸、苯甲酸、苹果酸和山梨酸）,置于厌氧工作站中,厌氧培养4 h后提取食糜中基因组DNA,应用绝对定量PCR技术测定食糜中乳杆菌属Lactobacillus、双歧杆菌属Bifidobacterium、沙门菌属Salmonella和大肠埃希菌Escherichia coli的数量变化.随后进一步选择抑菌活性较强的甲酸、乙酸、丁酸、乳酸、柠檬酸研究其抑菌活性的浓度梯度效应.【结果和结论】成功建立了体外全食糜厌氧培养体系,研究结果发现,甲酸、丁酸和柠檬酸能呈剂量依赖性地抑制细菌增殖,而乙酸对总菌数量影响不大;对益生菌而言,柠檬酸能显著抑制乳杆菌属和双歧杆菌属的增殖,但低剂量的乳酸（10 mmol·L^-1）能显著促进乳杆菌属和双歧杆菌属的增殖,且低剂量的乙酸（15 mmol·L^-1）也能促进双歧杆菌属的增殖;所选择的有机酸在浓度达到10-15 mmol·L^-1时,均能有效抑制病原菌（沙门菌和大肠埃希菌）的增殖.

我国民族地区地方课程及其政策研究

地方课程是为了保障和促进课程适应不同地区的需要,由地方根据国家课程管理政策、课程计划、课程标准和当地的政治、经济、文化、民族及学生发展需要,结合本地的优势和优良传统,充分利用本地的课程资源而自主开发并由地方管理的课程。我国在少数民族语言文字教材的开发与利用方面积累了丰富的经验,在新课程改革背景下,民族地区地方课程开发的政策、目标与内容等均有着新的内涵。