ClostridiumsaccharobutylicumDSM13864细胞表面理化特性及固定化细胞产丁醇的性能

糖丁基梭菌Clostridium saccharobutylicum DSM 13864能利用多种糖类为底物发酵产丁醇。本文研究了该菌体细胞表面的理化特性,并以砖块作为细胞固定化材料进行丁醇发酵。采用细菌吸附有机溶剂(MATS)法证明糖丁基梭菌细胞表面有强烈的亲水性,并且等电点在pH值为3左右,这些特性有利于菌体与表面亲水多孔的砖块吸附。在60g/L葡萄糖发酵培养基中,以5～8目砖块作为固定化材料,流速为1.1L/min,发酵48h后,丁醇的浓度、得率和生产率分别达到11.02g/L、0.18g/g和0.23g/(L·h),相比悬浮细胞发酵分别提高了10.53%、5.88%和9.52%。结果表明:砖块作为一种固定化材料可有效提高糖丁基梭菌的发酵产丁醇水平。     

自产气气提与纤维床反应器耦合发酵生产丁醇

采用发酵产物中的二氧化碳（CO₂）和氢气（H₂）作为循环气提气源,对丙酮丁醇梭菌（Clostridium acetobutylicum CGMCC 5234）发酵产物进行原位气提,实现丙酮、丁醇和乙醇混合物（ABE）的连续纤维床固定化发酵生产。连续发酵实验进行了12批次共309 h,总溶剂ABE当量浓度为133.3 g·L^-1（其中丁醇 83.5 g·L^-1,丙酮38.4 g·L^-1,乙醇11.4 g·L^-1）,葡萄糖消耗率为1.29 g·（L·h） ^-1,总溶剂ABE产率为0.431 g·（L·h） ^-1,转化率为0.333 g·g^-1,其中丁醇产率为0.270 g·（L·h） ^-1,转化率为 0.209 g·g^-1,发酵液中丁醇浓度控制在8～12 g·L^-1,显著优于游离发酵的结果。气提提取之后冷凝的ABE溶液出现分层现象,其中丁醇相丁醇浓度高达603.7 g·L^-1,极大地减缓后续分离提纯的负担。结果表明,自产气循环气提与纤维床固定化耦合连续发酵生产ABE（特别是丁醇）的工艺具有可行性和竞争力。     

The effects of dilution rate and glucose concentration on continuous acetone–butanol–ethanol fermentation by Clostridium acetobutylicum immobilized on bricks

BACKGROUND: Owing to the rapid depletion of petroleum fuel, the production of butanol through biological routes has attracted increasing attention. However, low butanol productivity severely impedes its potential industrial production. It is known that the immobilization of whole cells can enhance productivity in the acetone‐butanol‐ethanol (ABE) continuous fermentation process. Therefore, the objective of this study was to develop a low‐cost continuous operation for butanol production. RESULTS: Bricks were chosen as cell support because of their low cost and ease of use for immobilization. The solvent productivity for the bricks with immobilized cells was 0.7 g L^?1 h^?1, 1.89 times that of free cells (0.37 g L^?1 h^?1) at a dilution rate of 0.054 h^?1. The productivity improvement can contribute to greater retention of biomass inside the reactor due to immobilization. The increase in glucose feed concentration raised total solvent production. However, it resulted in a decrease in yield (grams of solvents produced per gram of glucose introduced). Continuous operation with immobilized cells at a dilution rate of 0.107 h^?1 resulted in a solvent productivity of 1.21 g L^?1 h^?1, 2.1 times that of the operation at 0.027 h^?1. However, the yield (butanol produced per glucose consumed) was decreased to 0.19 from 0.29 under the same glucose feeding condition of 60 g L^?1. CONCLUSION: The increase in dilution rate and feed glucose concentration enhanced productivity, but decreased the utilization of substrates and the final solvent concentration. Therefore, a balance between productivity and glucose utilization is required to ensure continuous process operation. Copyright © 2011 Society of Chemical Industry     

种子扩大培养过程对类人胶原蛋白规模化生产的影响

为了建立最优的类人胶原蛋白(HLC)的种子扩大培养过程,考察了三级种子培养过程中不同移种阶段和不同种子培养基对发酵过程的影响。结果表明,在对数期后期移种,HLC产率最高;当种子培养基中葡萄糖浓度为20 g·L-1时,其后发酵过程所需的培养时间较短,HLC表达量较高,HLC平均产率最高,达到0.518 g·L-1·h-1...     

Assessment of in situ butanol recovery by vacuum during acetone butanol ethanol (ABE) fermentation

BACKGROUND: Butanol fermentation is product limiting owing to butanol toxicity to microbial cells. Butanol (boiling point: 118 °C) boils at a higher temperature than water (boiling point: 100 °C) and application of vacuum technology to integrated acetone–butanol–ethanol (ABE) fermentation and recovery may have been ignored because of direct comparison of boiling points of water and butanol. This research investigated simultaneous ABE fermentation using Clostridium beijerinckii 8052 and in situ butanol recovery by vacuum. To facilitate ABE mass transfer and recovery at fermentation temperature, batch fermentation was conducted in triplicate at 35 °C in a 14 L bioreactor connected in series with a condensation system and vacuum pump. RESULTS: Concentration of ABE in the recovered stream was greater than that in the fermentation broth (from 15.7 g L^?1 up to 33 g L^?1). Integration of the vacuum with the bioreactor resulted in enhanced ABE productivity by 100% and complete utilization of glucose as opposed to a significant amount of residual glucose in the control batch fermentation. CONCLUSION: This research demonstrated that vacuum fermentation technology can be used for in situ butanol recovery during ABE fermentation and that C. beijerinckii 8052 can tolerate vacuum conditions, with no negative effect on cell growth and ABE production. Copyright © 2011 Society of Chemical Industry     

Selective recovery of acetone-butanol-ethanol from aqueous mixture by pervaporation using immobilized ionic liquid polydimethylsiloxane membrane

An effective in situ recovery of acetone, butanol and ethanol (ABE) from fermentation broth is requisite to overcome the low productivity of ABE production. Pervaporation has proven to be one of the best methods for recovering ABE from fermentation broth. We fabricated an immobilized ionic liquid-polydimethylsiloxane (PDMS) membrane in which a [Tf₂N]^? based ionic liquid covalently bound to the PDMS backbone polymer and used it to recover ABE from aqueous solution by pervaporation. Permeate flux of immobilized IL-PDMS membrane was 7.8 times higher than that of conventional supported IL-PDMS membrane (where ILs are physically absorbed on the supported membrane). Butanol enrichment factor of immobilized IL-PDMS membrane was three-times higher than that of PDMS membrane. In addition, high enrichment factor both to acetone and ethanol as well as high operational stability of immobilized IL-PDMS membrane can enhance the efficacy of ABE recovery by employing this membrane.     

Tailoring polymeric composite gel beads-encapsulated microorganism for efficient degradation of phenolic compounds

Phenol and its derivatives are highly toxic pollutants in industrial wastewater for the ecological environ-ments, so there is essential attention to develop effective means of removing these harmful substances from water. In this work, the microorganism was immobilized into polymeric composite gel beads pre-pared by the effective recombination of natural abundant chitosan (CS) and industrial polyvinyl alcohol (PVA) for treating phenolic compounds. The degradation rate of 99.5％ can be achieved to treat 100 mg·L-1 of phenol at 30 ℃ using the fresh resultant immobilized microorganism, where only 21.1％degradation rate was obtained by the free microorganism under the identical conditions. The recycling experiments of repeated 90 times to treat 100 mg·L-1 of phenol displayed that the degradation rate of phenol was stable to 99％with the appearance of beads unchanged significantly, indicating the immobi-lized microorganism possessed excellent operating stability. Moreover, while the phenol derivatives of 100 mg·L-1 were treated catalytically including p-methylphenol, catechol, and o-aminophenol for 24 h by the immobilized microorganism, the degradation rates were all above 95％. The immobilized microor-ganism into PVA-CS polymeric composite with excellent operating stability and degradation activity would provide a feasible solution for treating phenolic compounds in water in industrial applications.     

利用肺炎克雷伯氏菌以葡萄糖和磷酸铵盐为底物生产2,3-丁二醇

1 INTRODUCTION Interest in microbial production of 2,3-butanediol has been increasing recently due to the extensive indus-trial application of this product. This colorless and odorless liquid with a high boiling point and a low freezing point is a potential valuable fuel additive. Its heating value is 27.198kJ·g-1, which is quite near the value of ethanol (29.055kJ·g-1). Besides, condensation of diol to methyl ethyl ketone (MEK) coupled with subsequent hydrogenation yields octane isom…     

H‐B‐E (hexanol‐butanol‐ethanol) fermentation for the production of higher alcohols from syngas/waste gas

CO, H₂, and CO₂ are major components of syngas and some industrial CO‐rich waste gases (e.g. waste gases from steel industries), besides some additional minor compounds. It was recently shown that those gases can be bioconverted, by acetogenic/solventogenic bacteria, into ethanol and higher alcohols such as butanol, but also hexanol, through the so‐called HBE fermentation. That process presents some advantages over existing chemical conversion processes. This paper reviews HBE fermentation from C1‐gases after briefly describing the more conventional ABE (acetone‐butanol‐ethanol) fermentation from carbohydrates by Clostridium acetobutylicum, in order to allow for comparison of both processes. Although acetone may appear in carbohydrate fermentation, alcohols are the only major end‐metabolites in the HBE process with Clostridium carboxidivorans. The few acetogenic bacteria known to metabolize C1‐gases and produce butanol or higher alcohols are described. Clostridium carboxidivorans has been used in most cases. Bioconversion of the gaseous substrates takes place in two stages, namely acidogenesis (production of acids) followed by solventogenesis (production of alcohols), characterized by different optimal fermentation conditions. Major parameters affecting each bioconversion stage as well as the overall fermentation process are analyzed. Although it has been claimed that acidification is required in ABE fermentation to initiate the solventogenic stage, strong acidification seems to some extent not to be a prerequisite for solventogenesis in the HBE process. Bioreactors potentially suitable for this type of bioconversion process are described as well. © 2017 Society of Chemical Industry     

Clostridium acetobutylicum细胞的无机载体吸附固定化及其应用研究

为避免渗透汽化膜原位分离过程中丁醇生产菌对膜的污染,对无机载体吸附固定Clostridium acetobutylicum XY16进行了研究,考察了多种无机载体对菌体的固定效率及其发酵产丁醇性能的影响.研究发现:在静电引力的作用下,携带正电荷的沸石对荷负电的菌体具有良好的吸附作用.在此基础上,对沸石载体进行负载阳离子改性,沸石负载铁离子改变了载体表面Zeta电位,可增强对菌体的固定效率,并提高发酵性能.当培养基中葡萄糖浓度为60 g?L?1时,添加Fe3+-沸石18%(W/V)进行批式发酵,总溶剂的转化率为0.31 g?g?1,对菌体的固定效率达到87%,比未改性沸石提高了22%,丁醇产量为13.5 g?L?1,总溶剂可达20 g?L?1,比沸石改性前分别提高了8%和11.1%.对该材料固载的细胞进行4次重复批式发酵,总溶剂的基质得率与游离细胞批式发酵结果类似.以上研究结果表明Fe3+-沸石对Clostridium acetobutylicum XY16具有较好的细胞固定效率,并对其生产性能具有一定的促进作用,适宜作为丁醇生产菌的吸附载体.     

渗透汽化法从丙酮-丁醇-乙醇中分离浓缩丁醇

发酵法生产丁醇的产物质量浓度很低,为了实现丁醇的高效分离浓缩,文中采用渗透汽化膜分离技术对模型发酵液(丙酮、丁醇、乙醇混合溶液,ABE)进行浓缩实验。结果表明:随着温度、真空度、错流速度、料液质量浓度的增大,丁醇通量上升;渗透汽化膜对丁醇选择性在温度50℃时最佳,并随真空度的减小而减小,随料液质量浓度的增大而降低。实验证明,渗透汽化法能实现丁醇的高效分离浓缩,并且利用串联阻力溶解扩散模型可较好地预测ABE溶液体系中各组分的传质和分离效果。     

PDMS/ceramic composite membrane for pervaporation separation of acetone–butanol–ethanol (ABE) aqueous solutions and its application in intensification of ABE fermentation process

Pervaporation (PV) has attracted increasing attention because of its potential application in bio-butanol recovery from fermentation process. In this work, PDMS/ceramic composite membrane was employed for PV separation of acetone–butanol–ethanol (ABE) aqueous solutions. The influence of coupling effect on the molecular transport during the PV process was systematically investigated. The separation performance and transport phenomena of ABE molecules were discussed based on the analysis and calculation of physicochemical properties such as solubility parameter, polarity parameter, interaction parameter, activity coefficient. The results suggested that the ABE separation factor was mainly determined by the intrinsic solubility parameter and driving force. Coupling effect in the ABE multicomponent system was closely related to the interaction parameters between components themselves and between component and membrane. Also, the PDMS membrane was integrated with ABE fermentation to construct an efficient intensification process. It was found that the rate matching of fermentation and in situ removal could improve the ABE productivity by 2 times.     

发酵-渗透汽化连续耦合合成ABE的动力学

采用PDMS膜生物反应器和丙酮丁醇梭菌进行了生产ABE的封闭循环连续发酵实验,研究了发酵和渗透汽化分离连续耦合条件下的发酵动力学行为。发酵-分离连续耦合实验运行持续时间长达192 h。运行过程中,细胞质量浓度维持在0.84～4.00 g/L,发酵液中ABE的总质量浓度为5.14～17.54 g/L,葡萄糖质量浓度大约为16.08～35.15 g/L,总体积产率为0.36 g/(L.h)。结果表明,膜生物反应器系统运行稳定,发酵-渗透汽化分离连续耦合生产ABE的操作模式具有可行性和优越性。     

基于果糖与葡萄糖不同混合比例的丙酮丁醇发酵

介绍了以不同底物的丁醇发酵结果,阐述了在以55g/L葡萄糖与果糖（1∶4）混合糖模拟菊芋物料为底物的丁醇发酵过程中存在果糖利用及丁醇产量较低等问题,研究了基于葡萄糖与果糖不同混合比例（1∶2、2∶3、3∶2及3∶1）的丁醇发酵性能。研究结果说明了随着混合比例提高,发酵时间由76h缩短至48h,菌体最大生物量OD620由2.1提高至4.3,而当葡萄糖与果糖混合比例为1∶2时,发酵过程中菌体细胞对果糖代谢能力最佳,且终点残糖浓度仅为2.1g/L,果糖利用效率达到95.03%,丁醇及总溶剂产量分别达到9.7g/L与16.0g/L。     

Characterization and application of a recombinant dopa decarboxylase from Harmonia axyridis for the efficient biosynthesis of dopamine

Here,a dopa decarboxylase (DDC) from Harmonia axyridis was heterogeneously expressed in Escherichia coli for the efficient biosynthesis of dopamine.For the production of recombinant DDC,the cultivation conditions including IPTG concentration,temperature and induction time were optimized and obtained an optimal specific enzyme activity of 51.72 U·mg-1 crude extracts.After the purification of DDC with a recovery yield of 68.79％,its activity was further characterized.The Vmax,Km,Kcat,and Kcat/Km of DDC for dihydroxyphenylalanine (dopa) were 0.02 mmol·ml-1·s-1,2.328 mmol·ml-1,10435.90 s-1 and 4482.77 ml·mmol-1·s-1,respectively.The highest DDC activity was observed at the condition of pH 7.5 and 45 ℃.With the purified DDC,the feasibility to produce dopamine from L-dopa was evaluated.The optimal yield was determined at the following bioconversion conditions:pH of 7.0,the reaction temper-ature of 40 ℃,0.4 mmol·L-1 of PLP and 4 g·L-1 of L-dopa.Subsequently,a fed-batch process for the pro-duction of dopamine was developed and the effect of oxygen was evaluated.The titer,yield and productivity of dopamine reached up to 21.99 g·L-1,80.88％ and 14.66 g·L-1h-1 at 90 min under anaer-obic condition.     

丙丁梭菌/酿酒酵母混合培养耦联乙酸外添强化丙酮合成─侧重LCA的ABE发酵

提出梭菌/酵母混合培养耦联乙酸外添体系强化丙酮合成的ABE发酵新策略,可以同时强化丁醇特别是丙酮的合成。与对照组相比,外添化学合成乙酸时,丁醇、丙酮质量浓度和丙酮/丁醇质量比分别达到13.91、8.27 g/L和0.59,增幅分别为19.6%、41.1%和18.0%;外添廉价的乙酸发酵上清液时,相应的发酵指标达到14.23、8.55 g/L和0.60,增幅分别为22.4%、46.0%和20.0%,发酵原料成本降低、丙酮发酵生产的可行性提高。结果表明,该发酵策略可刺激有利于梭菌生存和丁醇合成的4种氨基酸的分泌;可以在保证丁醇正常合成的前提下,适度抑制NADH再生、降低细胞能量周转、强化丙酮生物合成,进而显著改善了ABE发酵性能。     

Separation of a Biofuel: Recovery of Biobutanol by Salting‐Out and Distillation

The second generation biofuel butanol can be produced by acetone‐butanol‐ethanol (ABE) fermentation, but the separation from the broth is still challenging. Therefore, dipotassium hydrogen phosphate was investigated as salting‐out agent. The ABE fermentation broth was enriched by a prefractionator after being preheated. The enriched ABE solution was salted out by K₂HPO₄ solutions at different temperatures. The water in the supplemented ABE solution was largely removed by the salting‐out method. The energy requirements for the prefractionator and the butanol column were significantly reduced. The total energy demand for the recovery of acetone, butanol, and ethanol by salting‐out and subsequent distillation was optimized. With the salting‐out process, the entire salting‐out and distillation method turned out to be more energy‐saving than the conventional one.     

卷枝毛霉发酵产壳聚糖酶的条件优化

以壳聚糖为诱导物,诱导卷枝毛霉产生壳聚1糖酶,并对产酶备件进行了优化。通过单因素实验确定最佳产酶条件为：壳聚糖浓度0．8g·L-1、培养温度40℃、培养基pH值5．5、培养时间84h、摇床转速180r·min-1。     

Alternatives for the Purification of the Blend Butanol/Ethanol from an Acetone/Butanol/Ethanol Fermentation Effluent

Biobutanol is a biofuel with potential to substitute gasoline. It can be generated through fermentation of lignocellulosic material, by which acetone, butanol, and ethanol (ABE) are obtained and subsequently separated. Nevertheless, the blend ethanol/butanol itself is a fuel, so its separation could be not even necessary. An alternative is proposed to simplify the purification step of the ABE mixture, avoiding the separation of the ethanol/butanol blend. Intensification alternatives are suggested for the resulting structure. The proposed schemes are optimized through a stochastic approach, minimizing the total annual cost and the eco‐indicator 99. The individual risk index is computed for selected designs. The suggested designs reduce the individual risk index by around 30–66 %.     

Selective separation of n‐butanol from aqueous solutions by pervaporation using silicone rubber‐coated silicalite membranes

BACKGROUND: To use butanol as a liquid fuel and feedstock, it is necessary to establish processes for refining low‐concentration butanol solutions. Pervaporation (PV) employing hydrophobic silicalite membranes for selective recovery of butanol is a promising approach. In this study, the adsorption behavior of components present in clostridia fermentation broths on membrane material (silicalite powder) was investigated. The potential of PV using silicone rubber‐coated silicalite membranes for the selective separation of butanol from model acetone–butanol–ethanol (ABE) solutions was investigated. RESULTS: The equilibrium adsorbed amounts of ABE per gram of silicalite from aqueous solutions of binary mixtures at 30 °C increased as follows: ethanol (95 mg) < acetone (100 mg) < n‐butanol (120 mg). The amount of butanol adsorbed is decreased by the adsorption of acetone and butyric acid. In the separation of ternary butanol/water/acetone mixtures, the enrichment factor for acetone decreased, compared with that in binary acetone/water mixtures. In the separation of a model acetone–butanol–ethanol (ABE) fermentation broth containing butyric acid by PV using a silicone rubber‐coated silicalite membrane, the permeate butanol concentration was comparable with that obtained in the separation of a model ABE broth without butyric acid. The total flux decreased with decreasing feed solution pH. CONCLUSION: A silicone rubber‐coated silicalite membrane exhibited highly selective PV performance in the separation of a model ABE solution. It is very important to demonstrate the effectiveness of PV in the separation of actual clostridia fermentation broths, and to identify the factors affecting PV performance. Copyright © 2011 Society of Chemical Industry