新型生物絮凝剂REA-11的代谢模型建立与代谢网络分析

利用代谢通量分析方法,对谷氨酸棒杆菌Corynebacterium glutamicum CCTCC M201005分批发酵不同阶段和不同溶氧浓度下的代谢网络模型进行了计算,考察了代谢节点对絮凝剂REA-11合成的影响,并对C. glutamicum生长代谢过程中能量和还原力的产生及消耗问题进行分析.结果发现,磷酸戊糖途径(PP)通量在整个发酵过程中始终维持在较高的水平;REA-11合成通量随溶氧浓度的增加而降低,菌体合成通量则随溶氧水平的增加而增加;ATP通量的增加可以促进菌体生长,而与REA-11的合成呈负相关.     

枯草芽孢杆菌E79分批发酵动力学

基于Logistic和Leudeking-Piret方程,根据分批发酵过程中菌体生长、产物积累、总糖消耗、还原糖消耗及反应体系pH值的变化规律构建枯草芽孢杆菌E79发酵过程中菌体细胞生长、产物合成及基质消耗的动力学模型,应用SPSS11.5软件对数据进行计算与分析,Oirgin 7.5软件经非线性拟合与优化,获得了最佳...     

谷氨酸棒杆菌生物合成L-鸟氨酸的代谢流分析

应用代谢流平衡模型,通过物料衡算和Matlab线性规划的方法得到谷氨酸棒杆菌1009生物合成L-鸟氨酸的代谢流分布与理想代谢流分布.结果表明：在分批培养条件下,生物合成L-鸟氨酸的过程中,有58.6%的C架进入糖酵解途径,41.4%的C架进入戊糖磷酸途径,L-鸟氨酸的产量达到理论最大产率的65.4%;与理论值相比,应降低三羧酸循环的代谢流,同时减少副产物氨基酸和有机酸的生成.     

乳链菌肽补料分批发酵过程动力学模型

针对Lactococcus lactis subsp lctis W28生产乳链菌肽的发酵体系,建立了变体积补料分批发酵生产乳链菌肽的动力学模型,确定了模型参数值.结果表明,改变补料速率后菌体生长、乳酸积累、蔗糖消耗及乳链菌肽合成的模型计算值与实测值的平均相对偏差为4.84%,11.91%,13.17%及3.25%,因此所建动力学模型能较好地反映变体积补料分批发酵生产乳链菌肽的过程.     

瓜氨酸生产相关基因簇在谷氨酸棒杆菌中的组成型表达

构建1种组成型载体并将载体应用在表达瓜氨酸相关基因簇argCJBDF上。通过去除pXMJ19诱导型启动子上游阻遏蛋白lacI基因的方法,构建组成型质粒pXMJ19-lacI,并将谷氨酸棒杆菌中合成瓜氨酸途径的基因簇argCJBDF克隆到改造过的组成型载体中,实现瓜氨酸合成相关基因簇argCJBDF在谷氨酸棒杆菌的组成型表达。结果表明:重组菌在30℃摇瓶发酵72 h后,N-乙酰谷氨酸激酶的酶活达到(0.323±0.015)U/mg,瓜氨酸的产量达到4.33 g/L。成功构建的组成型表达载体,实现了外源基因簇argCJBDF在谷氨酸棒杆菌中的组成型表达。     

生物絮凝剂γ-PGA絮凝性能的研究

目前,以γ-聚谷氨酸(γ-PGA)为主要成分的生物絮凝剂广泛应用于环保、医药、食品领域.主要考察了γ-PGA的絮凝性能,实验结果表明,γ-PGA絮凝活性较高,热稳定性较高,具有较强的抗pH冲击能力.但其投加量偏大,且对溶解性有机物的去除效率不高,比较适合应用于处理低浓度工业废水以及河流水体的净化.     

三段式谷氨酸棒杆菌发酵生产生物絮凝剂的过程及动力学模拟(英文)

Fermentation of bioflocculant with Corynebacterium glutamicum was studied by way of kinetic modeling. Lorentzian modified Logistic model, time-corrected Luedeking–Piret and Luedeking–Piret type models were pro-posed and applied to describe the cell growth, bioflocculant synthesis and consumption of substrates, with the correlation of initial biomass concentration and initial glucose concentration, respectively. The results showed that these models could well characterize the batch culture process of C. glutamicum at various initial glucose con-centrations from 10.0 to 17.5 g·L?1. The initial biomass concentration could shorten the lag time of cel growth, while the maximum biomass concentration was achieved only at the optimal initial glucose concentration of 16.22 g·L?1. A novel three-stage fed-batch strategy for bioflocculant production was developed based on the model prediction, in which the lag phase, quick biomass growth and bioflocculant production stages were sequentially proceeded with the adjustment of glucose concentration and dissolved oxygen. Biomass of 2.23 g·L?1 was obtained and bioflocculant concentration was enhanced to 176.32 mg·L?1, 18.62% and 403.63%higher than those in the batch process, respectively, indicating an efficient fed-batch culture strategy for bioflocculant production.     

捷安肽素固定化细胞分批发酵过程动力学分析

用Sigmoid模型构建了5 L发酵罐固定化细胞分批发酵生产捷安肽素的非结构动力学模型,并对细胞生长、捷安肽素合成、葡萄糖消耗和总氮消耗的比速率进行了计算与分析.结果表明,Sigmoid模型能较好地拟合固定化细胞分批发酵生产捷安肽素的发酵过程,拟合动力学模型的相关系数R2大于0.971.细胞生长、捷安肽素合成、葡萄糖消...     

过量表达琥珀酸输出蛋白SucE对谷氨酸棒杆菌厌氧生产琥珀酸的影响

谷氨酸棒杆菌Corynebacterium glutamicum ATCC 13032在厌氧条件下通过三羧酸循环还原臂合成琥珀酸。高效地将细胞内的琥珀酸输出到胞外,对琥珀酸的生物合成具有重要意义。本实验以C.glutamicum XZ为出发菌株过表达琥珀酸输出蛋白表达基因suc E。突变株C.glutamicum XZ(p Exhsuc E)的琥珀酸得率提高了7%,生产率提高了19%。通量分析表明,过表达suc E基因后乙醛酸循环的相对通量提高了50%。采用两阶段培养,突变株C.glutamicum XZ(p Exhsuc E)的琥珀酸产量达到518 mmol·L-1,厌氧阶段的比生产率为0.95 mmol g CDW-1·h-1,1 mol glucose的平均得率为1.5 mol。     

壳聚糖作絮凝剂进行生物微粒分离的研究

本文通过对生物微粒谷氨酸菌体带电性质的测定，采用壳聚糖作絮凝剂对谷氨酸发酵液进行絮凝处理。研究了ＰＨ值、温度、絮凝剂的加入量及混合方式等因素对生物微粒谷氨酸菌体絮凝分离的影响。为工业微生物的分离提供了一条现实可行的途径。     

Three-stage fermentation and kinetic modeling of bioflocculant by Corynebacterium glutamicum

Fermentation of bioflocculant with Corynebacterium glutamicum was studied by way of kinetic modeling. Lorentzian modified Logistic model, time-corrected Luedeking–Piret and Luedeking–Piret type models ...     

不同供氧水平对L-精氨酸分批发酵过程的影响

以钝齿棒杆菌Corynebacterium crenatum SYPA5-5为研究菌株,通过不同摇瓶装液量试验,考察发酵过程中供氧对L-精氨酸合成的影响。作者分别采用发酵动力学模型和代谢流量分析对实验结果进行分析后发现：在发酵前期,高供氧使HMP途径更加活跃,生成大量NADPH促进菌体生长;高供氧控制同样利于L-精氨酸的合成,一方面是由于菌体的高葡萄糖摄入量,另一方面是由于有更多的流量从α-KG流向Arg的前体物质Glu。     

Modelling of the Corynebacterium glutamicum biosynthesis under aerobic fermentation conditions

This work concerns the modelling of the Corynebacterium glutamicum biosynthesis. At the beginning, the impulsive growth model of C. glutamicum under glutamate inhibition is established. According to this model, the analysis of the bioprocess stability is presented. Then, new objective functions are proposed and optimisation of C. glutamicum growth is presented. The results of the optimisation indicate that, although the growth of C. glutamicum is an aerobic process, the maximum of biomass productivity occurs under controlled penetration into the area of aerobic fermentation. Analytical results presented in this work are validated by numerical simulations.     

Transcriptome and Gene Ontology (GO) Enrichment Analysis Reveals Genes Involved in Biotin Metabolism That Affect l-Lysine Production in Corynebacterium glutamicum

Corynebacterium glutamicum is widely used for amino acid production. In the present study, 543 genes showed a significant change in their mRNA expression levels in l-lysine-producing C. glutamicum ATCC21300 than that in the wild-type C. glutamicum ATCC13032. Among these 543 differentially expressed genes (DEGs), 28 genes were up- or downregulated. In addition, 454 DEGs were functionally enriched and categorized based on BLAST sequence homologies and gene ontology (GO) annotations using the Blast2GO software. Interestingly, NCgl0071 (bioB, encoding biotin synthase) was expressed at levels ~20-fold higher in the l-lysine-producing ATCC21300 strain than that in the wild-type ATCC13032 strain. Five other genes involved in biotin metabolism or transport—NCgl2515 (bioA, encoding adenosylmethionine-8-amino-7-oxononanoate aminotransferase), NCgl2516 (bioD, encoding dithiobiotin synthetase), NCgl1883, NCgl1884, and NCgl1885—were also expressed at significantly higher levels in the l-lysine-producing ATCC21300 strain than that in the wild-type ATCC13032 strain, which we determined using both next-generation RNA sequencing and quantitative real-time PCR analysis. When we disrupted the bioB gene in C. glutamicum ATCC21300, l-lysine production decreased by approximately 76%, and the three genes involved in biotin transport (NCgl1883, NCgl1884, and NCgl1885) were significantly downregulated. These results will be helpful to improve our understanding of C. glutamicum for industrial amino acid production.     

酵母细胞连续发酵过程振荡现象的研究进展

振荡现象在连续发酵过程中普遍存在,本文综述了酿酒酵母连续发酵中不同类型振荡现象的研究进展。一类以乙醇连续发酵过程中参数振荡为代表的特殊振荡现象,普遍存在于工业发酵过程,对发酵系统的稳定运行造成不利影响。本文论述了这类振荡现象产生的机理、调控策略的研究进展及其潜在的应用价值。     

Fermentative Production of Halogenated Tryptophan Derivatives with Corynebacterium glutamicum Overexpressing Tryptophanase or Decarboxylase Genes

The aromatic amino acid l -tryptophan serves as a precursor for many valuable compounds such as neuromodulators, indoleamines and indole alkaloids. In this work, tryptophan biosynthesis was extended by halogenation followed by decarboxylation to the respective tryptamines or cleavage to the respective indoles. Either the tryptophanase genes tnaAs from E. coli and Proteus vulgaris or the aromatic amino acid decarboxylase genes AADCs from Bacillus atrophaeus, Clostridium sporogenes, and Ruminococcus gnavus were expressed in Corynebacterium glutamicum strains producing (halogenated) tryptophan. Regarding indoles, final titers of 16 mg L⁻¹ 7-Cl-indole and 23 mg L⁻¹ 7-Br-indole were attained. Tryptamine production led to a much higher titer of 2.26 g L⁻¹ upon expression of AADC from B. atrophaeus. AADC enzymes were shown to be active with halogenated tryptophan in vitro and in vivo and supported production of 0.36 g L⁻¹ 7-Br-tryptamine with a volumetric productivity of 8.3 mg L⁻¹ h⁻¹ in a fed-batch fermentation.     

普那霉素发酵与吸附分离耦合过程动力学

根据S.pristinaespiralis E-71普那霉素发酵过程的代谢特性提出了一个针对产物合成期的普那霉素合成动力学方程,结合液膜-孔扩散理论,建立了描述2.5L通气搅拌发酵罐中JD-1大孔吸附树脂吸附分离原位耦合发酵过程的动力学模型,并获得产物生成速率常数、产物抑制常数及液膜传质和孔内扩散系数。结果表明该发酵-吸附耦合过程动力学模型能较好地描述这一原位分离耦合发酵生产普纳霉素过程。在此基础上,考察了树脂添加量及树脂半径对原位分离耦合发酵过程的影响,结果表明添加JD-1树脂能有效移走发酵液主体相中高达90%的普那霉素,且原位分离效果随树脂粒径减小而增强,在一定范围内随树脂添加量的增加而增强,当添加70g.L-1半径为0.195mm的树脂时,普纳霉素产量达到1.01g.L-1,其中被树脂吸附的高于95%。