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.

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.

Study on the Substrate Inhibition and the Method of Disarming Inhibition in the Fermentation Process of Hyaluronic Acid

[Objective] The research aimed to search and obtain the fermentation method of hyaluronic acid with the high yield.[Method] In the production process of hyaluronic acid by the microbial fermentation method,the influence of substrate concentration on the fermentation was explored.[Result] The glucose had the biggest influence on the hyaluronic acid fermentation.The low concentration of glucose only could synthetize a little bacteria and hyaluronic acid,and the high concentration of glucose could inhibit the growth of bacteria and the formation of hyaluronic acid.Via the exploratory experiment,the fed-batch fermentation could disarm the substrate inhibition.The concrete method was adding 2% glucose before the start of fermentation,and adding 2% glucose at the 14th hour of fermentation,and adding 2% glucose again at the 22nd hour of fermentation.[Conclusion] In the microbial fermentation process,the fed-batch fermentation could disarm the substrate inhibition and obtain the hyaluronic acid with the larger relative molecular mass and the higher yield.

STUDIES OF DISSOLVED OXYGEN IN PRODUCTION OF D-RIBOSE BY FERMENTATION

This paper mainly dealt with the dissolved oxygen in production of D-ribose by fermentation. The oxygen transfer coefficients of common flask, buffed flask and jar fermentor were determined.

An Approach to Continuous Approximation of Pareto Front Using Geometric Support Vector Regression for Multi-objective Optimization of Fermentation Process

The approaches to discrete approximation of Pareto front using multi-objective evolutionary algorithms have the problems of heavy computation burden, long running time and missing Pareto optimal points. In order to overcome these problems, an approach to continuous approximation of Pareto front using geometric support vector regression is presented. The regression model of the small size approximate discrete Pareto front is constructed by geometric support vector regression modeling and is described as the approximate continuous Pareto front. In the process of geometric support vector regression modeling, considering the distribution characteristic of Pareto optimal points, the separable augmented training sample sets are constructed by shifting original training sample points along multiple coordinated axes. Besides, an interactive decision-making(DM)procedure, in which the continuous approximation of Pareto front and decision-making is performed interactively, is designed for improving the accuracy of the preferred Pareto optimal point. The correctness of the continuous approximation of Pareto front is demonstrated with a typical multi-objective optimization problem. In addition,combined with the interactive decision-making procedure, the continuous approximation of Pareto front is applied in the multi-objective optimization for an industrial fed-batch yeast fermentation process. The experimental results show that the generated approximate continuous Pareto front has good accuracy and completeness. Compared with the multi-objective evolutionary algorithm with large size population, a more accurate preferred Pareto optimal point can be obtained from the approximate continuous Pareto front with less computation and shorter running time. The operation strategy corresponding to the final preferred Pareto optimal point generated by the interactive DM procedure can improve the production indexes of the fermentation process effectively.

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.

一株产L-苹果酸黑曲霉菌株的诱变筛选及发酵培养基优化

为筛选一株产L-苹果酸能力强的黑曲霉菌株,通过紫外诱变与高浓度放线菌酮迭代诱变的方法,将野生型菌株诱变为一株产L-苹果酸能力强的黑曲霉菌株,并对其种子或发酵培养基成分进行优化。结果表明,诱变所得一株产L-苹果酸能力强的黑曲霉CGMCC NO.40550菌株,其摇瓶发酵时种子培养基最适葡萄糖浓度为60 g/L、最适氮源为(NH_4)_2SO_4 4.95 g/L,黑曲霉菌球形成最优转速220 r/min;发酵培养基最适葡萄糖和最适(NH_4)_2SO_4浓度分别为180 g/L和4.95 g/L,Cu SO_4·5H_2O为其生产苹果酸最佳微量元素,最适添加量为0.065 g/L。通过单因素实验的优化,优化后的培养基更有利于L-苹果酸的合成,发酵96 h时L-苹果酸产酸量达到18.15 g/L,显著提高了245%,L-苹果酸占总酸的百分比达到71.69%。本研究为L-苹果酸的工业化生产奠定基础。

The Pichia pastoris enzyme production platform:From combinatorial library screening to bench-top fermentation on residual cyanobacterial biomass

The demand for industrial enzymes is continually rising,fueled by the growing need to shift towards more sustainable industrial processes.However,making efficient enzyme production strains and identifying optimal enzyme expression conditions remains a challenge.Moreover,the production of the enzymes themselves comes with unavoidable impacts,e.g.,the need to utilize secondary feedstocks.Here,we take a more holistic view of bioprocess development and report an integrative approach that allows us to rapidly identify improved enzyme expression and secretion conditions and make use of cyanobacterial waste biomass as feed for supporting Pichia pastoris fermentation.We demonstrate these capabilities by producing a phytase secreted by P.pastoris that is grown on cyanobacterium hydrolysate and buffered glycerol-complex(BMGY)medium,with genetic expression conditions identified by high-throughput screening of a randomized se-cretion library.When our best-performing strain is grown in a fed-batch fermentation on BMGY,we reach over 7000 U/mL in three days.

脱落酸的摇瓶发酵工艺优化研究

【目的】通过脱落酸的摇瓶发酵工艺优化,提高脱落酸的摇瓶发酵水平,从而减少摇瓶效价误差,有利于诱变效应的分析。【方法】通过工艺试验确定对脱落酸摇瓶发酵的影响因素,对影响因素进一步进行正交优化试验,得到脱落酸摇瓶培养基的最优配比组合浓度。【结果】脱落酸摇瓶配方中的麦麸可以完全被黄豆粉替代,替代后其摇瓶效价从0.171 g/L提高到0.550 g/L,提高幅度达221.6%。经过进一步正交试验,以黄豆粉、麦芽糖、乙二醇为影响因素,摇瓶产量为评价指标,摇瓶产量结果显示黄豆粉为最显著影响因子,其次为麦芽糖。得到最佳摇瓶配方为黄豆粉5 g/L、麦芽糖10 g/L、乙二醇4 g/L,花生粉4 g/L,葡萄糖4 g/L,硫酸镁1 g/L。摇瓶发酵效价从0.205 g/L提高到1.441 g/L,比对照提高602.9%,其提高幅度较大。【结论】发酵摇瓶中黄豆粉替代麦麸更有利于发酵过程中脱落酸菌产素水平的提高。

The uncoupled microbial fed-batch fermentation optimization based on state-dependent switched system

In the actual microbial fermentation process,excessive or insufficient substrate can produce inhibitory effects on cells growth.The artificial substrate feeding rules by past experiences have great blindness to keep substrate concentration in a given appropriate range.This paper considers that alkali feed depends on pH value of the solution and glycerol feed depends on glycerol concentration of the solution in the uncoupled microbial fed-hatch fermentation process,and establishes a state-dependent switched system in which the flow rates of glycerol and alkali,the number of mode switches,the mode sequence and the switching times are prior unknown.To maximize the yield of target product 1,3-Propanediol(1,3-PD),we formulate a switching optimal control problem with the flow rates of glycerol and alkali,the number of mode switches,the mode sequence and the switching times as decision variables,which is a mixed-integer dynamic programming problem.For solving the mixed-integer dynamic programming problem,the control parametrization technique,the time scaling transformation and the embedded system technology are used to obtain an approximate parameter optimization problem.By using a parallel optimization algorithm,we obtain the optimal control strategies.Under the obtained optimal control strategies,the 1,3-PD yield at the terminal time is increased significantly compared with the previous results.

卡那链霉菌培养基碳源、氮源及微量元素优化研究

通过单因素及多因素实验对卡那链霉菌生长繁殖的培养基进行了优化研究。结果表明:影响卡那链霉菌生长的固体培养基主要因素有碳源的选择及培养基灭菌前pH值调节,实验确定最佳的碳源为饴糖,培养基灭菌前pH:7.50左右;影响卡那链霉菌积累代谢产物的发酵培养基主要因素有碳源的选择,微量元素的添加,实验确定结果为:最佳碳源是乳糖,其次培养基中添加0.03%FeSO4后发酵液的滤速比对照提高了65.0%,摇瓶效价比对照提高了21.97%。

卑霉素摇瓶发酵工艺研究

根据代谢发酵控制原理,采用二次回归正交旋转组合设计,对卑霉素摇瓶发酵培养基组分及其接种量、装量和初始pH摇瓶发酵条件进行了优化。结果表明,卑霉素摇瓶发酵培养基的最优配方为:豆饼粉45 g/L,可溶性淀粉5 g/L,甘露醇24 g/L,葡萄糖5 g/L,硫酸铵2 g/L,硫酸镁0.05 g/L;最优发酵条件为:摇瓶装量100 mL/L,接种量8%,C aCO35 g/L(调节pH值),在温度28℃、发酵周期40 h的优化条件下,得到卑霉素的效价值为77.12μg/mL,较对照(64.11μg/mL)提高了20.29%。

平菇液体菌种摇瓶和发酵罐生长动力学模型的比较

作者选用玉米粉豆粕粉蔗糖液体培养基,分别采用摇瓶和40 L全自动机械搅拌通风发酵罐培养平菇天达300液体菌种,两种培养方式的菌丝体生长动力学模型均符合Logistic方程。摇瓶培养周期为8 d,最大比生长速率是0.050 h^(-1),菌丝体质量浓度是1.5001 g/dL。发酵罐培养周期是84 h,最大比生长速率是0.110 h^(-1),菌丝体质量浓度是1.4750 g/dL。应用发酵罐培养平菇天达300液体菌种更为高效。然而,摇瓶培养的液体菌种菌丝球直径小,单位体积培养液中菌丝球数量是发酵罐的1.4倍,可能与发酵罐培养过程中培养液的粘度下降速度快于摇瓶有关。

海洋红酵母培养条件的研究

通过碳源、氮源及主要营养与环境条件等对海洋红酵母产菌量的影响试验,以及蔗糖、蛋白胨、酵母膏三因素三水平的正交试验,获得了海洋红酵母的最佳发酵条件:蔗糖1.5%,蛋白胨1.0%,酵母膏0.5%,磷酸二氢钾0.15%,硫酸镁0.01%,氯化钠1.0%,初始pH5.0,接种量8%,500mL三角瓶中培养基装量为80mL,发酵温度为28℃,摇床200r/min。在此优化的培养条件下,海洋红酵母的产菌量可达9.7亿个/mL,比优化前发酵培养基产菌量(5.6亿个/mL)提高了73.2%,比单因素试验结果(8.1亿个/mL)提高了19.8%。

白色金针菇摇瓶发酵培养基的优化研究

以菌丝球干质量、密度、直径为考察指标,利用单因素试验和L9(34)正交试验对白色金针菇摇瓶发酵培养基进行优化。结果表明,最适摇瓶培养基配方为:葡萄糖10 g/L、红糖13 g/L、黄豆粉3 g/L、KH_2PO_40.5 g/L、MgSO_40.5 g/L、VB10.01 g/L。在此条件下,白色金针菇菌丝球干质量达到15.48 g/L,菌丝球密度66.48个/mL,菌丝球直径为1.45 mm。

大豆蛋白废水生产单细胞蛋白的菌种选择及其培养条件

针对大豆蛋白生产废水的水质特性,选择了产朊假丝酵母(Candida utilis)、热带假丝酵母(Candida tropicalis)、白地霉(Geotrichum candidum link)、解脂假丝酵母解脂变种(Candida lipolytica)和扣囊拟内孢霉(Endomycopsis fiburiger)等5种工业生产酵母,作为以大豆蛋白废水生产单细胞蛋白(Single Cell Protein,SCP)的菌种,并通过摇瓶培养实验,对其培养生长条件进行了研究。结果表明,白地霉的最佳培养条件为C/N37(马铃薯-葡萄糖培养基),pH6.5,25℃,180r/min;产朊假丝酵母为C/N5(麦氏琼脂培养基),pH6,25℃,180r/min;热带假丝酵母为C/N37(马铃薯-葡萄糖培养基),pH5.5,25℃,210r/min;解脂假丝酵母为C/N37(马铃薯-葡萄糖培养基),pH5.5,25℃,180r/min;扣囊拟内孢霉为C/N37(马铃薯-葡萄糖培养基),pH6,25℃,180r/min。5种酵母菌基本都适合生长在含糖量较高,pH偏酸性,温度在25℃左右的环境当中,比较适合利用大豆蛋白废水生产SCP,为菌种的复配提供了依据,为实现利用大豆蛋白废水生产SCP奠定了基础。

不同茯苓化学成分的研究

本文测定了天然茯苓、发酵茯苓、药性发酵茯苓和复合药性发酵茯苓的多糖、总糖、氨基酸和微量元素的含量。研究结果表明不同茯苓的化学成分有较大差异,探讨了上述差异产生的原因。上述研究为茯苓相关保健食品和药品的开发提供了科学依据和参考。