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Fang Gao Andrew J. Daugulis 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(2):302-306
BACKGROUND: Biphasic systems with immiscible solvents have been studied for in situ product removal, and have shown improvements in bioreactor performance, however, problems associated with solvent biocompatibility, bioavailability and operation have been identified. One alternative is the solid–liquid system in which polymer beads are used, absorbing and removing target compounds from the aqueous phase while maintaining equilibrium conditions. This work aims to identify polymer properties that may be important in polymer selection for selected biotransformation molecules including 2‐phenylethanol, cis‐1,3‐indandiol, iso‐butanol, succinic acid and 3‐hydroxybutyrolactone. RESULTS: Relatively hydrophobic compounds (e.g. 2‐phenylethanol) tend to be absorbed by polymers better than hydrophilic ones (e.g. iso‐butanol) based on partition coefficient tests; values as high as 80 were obtained for the former and < 3 for the latter. Owing to the presence of polar functional groups on these compounds, polar polymers such as Hytrel® performed better than non‐polar ones such as Kraton®. Crystallinity and intermolecular hydrogen‐bonding were also found to be important polymer properties. CONCLUSION: Polymers showed excellent results in absorbing hydrophobic compounds such as aromatic alcohols, and positive results in absorbing hydrophilic compounds but to a lesser extent. Grafting hydrophilic functional groups onto polymers may be a promising approach for extending polymer uptake capabilities and is currently being investigated. Copyright © 2009 Society of Chemical Industry 相似文献
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Julian T S Dafoe Andrew J Daugulis 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2011,86(11):1379-1385
BACKGROUND: A solid‐liquid two‐phase partitioning bioreactor (TPPB) was used in the biotransformation of indene to cis‐(1S,2R)‐indandiol by Pseudomonas putida 421‐5 (ATCC 55687). Metered substrate feeding in single‐phase operation, or delivery from an immiscible liquid, have previously been employed to regulate the exposure of the biocatalyst to inhibitory concentrations of the substrate. In contrast, the solid‐liquid platform provided in situ substrate addition (ISSA) as well as simultaneous it in situ product removal (ISPR) as a means of overcoming substrate and product toxicity. Three different modes of operation were compared for their effects on the performance of this biotransformation: single‐phase, fed‐batch operation was carried out as a benchmark in 2.75 L aqueous medium, and subsequently with the inclusion of either 700 g liquid silicone oil or 700 g solid polymer beads. RESULTS: Biphasic modes achieved a 3‐fold productivity improvement with respect to single‐phase (30 to 90 mg L?1 h?1), and solid‐liquid productivity was similar to liquid‐liquid operation while achieving more extensive removal of inhibitory compounds resulting in a slightly higher product titer (1.29 vs 1.16 g L?1). The operability of the reactor was improved by the phase stability of the solid polymer beads relative to immiscible organic solvents, preventing emulsion formation and facilitating analytics. CONCLUSION: Solid polymer beads replaced the immiscible liquid auxiliary phase for substrate delivery while performing simultaneous inhibitory molecule sequestration. Copyright © 2011 Society of Chemical Industry 相似文献
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Jean‐Marc Aldric Philippe Thonart 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2008,83(10):1401-1408
BACKGROUND: In the framework of biological processes used for waste gas treatment, the impact of the inoculum size on the start‐up performance needs to be better evaluated. Moreover, only a few studies have investigated the behaviour of elimination capacity and biomass viability in a two‐phase partitioning bioreactor (TPPB) used for waste gas treatment. Lastly, the impact of ethanol as a co‐substrate remains misunderstood. RESULTS: Firstly, no benefit of inoculation with a high cellular density (>1.5 g L?1) was observed in terms of start‐up performance. Secondly, the TPPB was monitored for 38 days to characterise its behaviour under several operational conditions. The removal efficiency remained above 63% for an inlet concentration of 7 g isopropylbenzene (IPB) m?3 and at some time points reached 92% during an intermittent loading phase (10 h day?1), corresponding to a mean elimination capacity of 4 × 10?3 g L?1 min?1 (240 g m?3 h?1) for a mean IPB inlet load of 6.19 × 10?3 g L?1 min?1 (390 g m?3 h?1). Under continuous IPB loading, the performance of the TPPB declined, but the period of biomass acclimatisation to this operational condition was shorter than 5 days. The biomass grew to approximately 10 g L?1 but the cellular viability changed greatly during the experiment, suggesting an endorespiration phenomenon in the bioreactor. It was also shown that simultaneous degradation of IPB and ethanol occurred, suggesting that ethanol improves the biodegradation process without causing oxygen depletion. CONCLUSION: A water/silicone oil TPPB with ethanol as co‐substrate allowed the removal of a high inlet load of IPB during an experiment lasting 38 days. Copyright © 2008 Society of Chemical Industry 相似文献
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Two‐phase partitioning bioreactors (TPPBs) have been recently demonstrated to be capable of using solid polymers as the absorbing/desorbing phase. In this paper, we examine the possibility of using a siloxane‐based copolymer as this phase. Copolymers were prepared using vinyl terminated oligo(dimethylsiloxane‐co‐diphenylsiloxane), copolymerized with varying amounts of the comonomers ethylene glycol dimethacrylate (EGDMA), N‐vinyl pyrrolidone (NVP), or acrylic acid (AA), via free radical polymerization. The absorption rate of phenol as a representative pollutant into these polymers from water was measured. The inclusion of a water‐soluble comonomer resulted in swelling of the polymers in water, enhanced total phenol absorption, but reduced phenol diffusivity. 相似文献
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Jennifer V. Littlejohns Kim B. McAuley Andrew J. Daugulis 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(2):173-184
BACKGROUND: Airlift solid–liquid two‐phase partitioning bioreactors (SL‐TPPBs) have been shown to be effective for the treatment of gas streams containing benzene, toluene, ethylbenzene and o‐xylene (BTEX). The airlift SL‐TPPB is a low‐energy system that utilizes a sequestering phase of solid silicone rubber beads (10%v/v) that will uptake and release large amounts of BTEX in order to maintain equilibrium conditions within the system. This increases mass transfer from the gas phase during dynamic loading periods and improves degradation performance. This study discusses the development and analysis of a steady‐state, tanks‐in‐series mathematical model, arising from mass balances on BTEX and oxygen in the gas, aqueous and polymer phases to predict the performance of the airlift SL‐TPPB over various gas flow rates and BTEX loadings. RESULTS: An estimability analysis on model parameters determined that the parameters to which model output is most sensitive are those that affect biological activity, which were targeted for estimation. The developed tanks‐in‐series model was able to predict the removal of BTEX components and dissolved oxygen concentrations over various inlet loadings (20, 60 and 100 mg L?1 h?1) and gas flow rates (2,3 and 4 L min?1) that resulted in a range of system performance from effective BTEX treatment to oxygen limiting conditions. CONCLUSIONS: The model developed, with estimated parameters, provides a valuable tool to determine operating conditions that will result in favourable performance of the airlift SL‐TPPB. Copyright © 2009 Society of Chemical Industry 相似文献
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Guillermo Quijano Raúl Chávez‐Avila Raúl Muñoz Frédéric Thalasso Alberto Ordaz 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(10):1407-1412
BACKGROUND: Two‐phase partitioning bioreactors (TPPBs) are based on the addition of a non‐aqueous phase (NAP) to a biological process in order to overcome a limited delivery of gaseous substrates to the microorganisms in the case of compounds with low affinity for water. However, the high power input (Pg/V) required to disperse the NAP is often the major limitation for TPPB applications at full scale. Therefore, the accurate determination of the overall mass transfer coefficient (KLa) at low Pg/V values is a critical issue as these operational conditions are more attractive from a scale‐up point of view. RESULTS: NAP addition altered the typical shape of the dissolved oxygen curves used for KLa determination at the lowest Pg/V values tested (70–80 W m?3). Below a threshold Pg/V value of 600 W m?3, the presence of the NAP increased the error in KLa measurements up to 115% relative to controls deprived of NAP. CONCLUSIONS: The error in KLa measurements at low Pg/V values might be related to failures in the fundamental assumption regarding liquid phase homogeneity in the mass transfer model used. Copyright © 2010 Society of Chemical Industry 相似文献
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Marco Rito‐Palomares Andrew Lyddiatt 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2000,75(7):632-638
A two‐stage extraction process for the recovery of intracellular proteins from brewers' yeast was selected as a practical model system to study the implementation of polyethylene glycol (PEG)–phosphate aqueous two‐phase systems (ATPS). Disrupted all suspensions generated by homogenisation and bead milling were used to study the impact of cell debris upon the partition behaviour of the intracellular products (bulk protein, fumarase and pyruvate kinase). Regardless of their origin debris particles did not significantly influence the partition behaviour of the intracellular products in selected ATPS distant from the binodal and at volume ratios greater than one. Recycling of used PEG into the initial extraction stage did not significantly influence the protein partition behaviour in batch ATPS. In the polymer recycling studies in continuous ATPS using spray columns, the addition of fresh materials to make up the deficits of phase‐forming chemicals compensate any negative effect of the continuous recycling of the top PEG‐rich phase. The findings of these studies raise the potential application of ATPS processes for protein recovery from complex biological systems. © 2000 Society of Chemical Industry 相似文献
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Impact of polyethylene glycol as additive on the formation and extraction behavior of ionic‐liquid based aqueous two‐phase system 
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下载免费PDF全文 Mohammad Vahidnia Gholamreza Pazuki Shiva Abdolrahimi 《American Institute of Chemical Engineers》2016,62(1):264-274
Developing a novel Ionic‐liquid (IL) based aqueous two‐phase system (ATPS) with polyethylene glycol (PEG) as adjuvant for the separation of biomolecules is studied. This original work involves addition of various concentration of PEG (2000, 4000, and 6000 gr/mol) to 1‐butyl‐3‐methylimidazolium acetate+ potassium hydrogen phosphate ATPS to investigate their subsequent effect on phase diagrams and partitioning coefficient of α‐amylase. In another innovative aspect of this work, response surface methodology (RSM) based on three‐variable central composite design was employed to understand the effect of phase forming components on extraction studies of α‐amylase. The addition of small amount of PEG improved the partitioning coefficient of biomolecule. The effective excluded volume theory was applied to correlate the salting‐out ability. As a result, it can be stated that the proposed system can effectively be used in separation and purification studies instead of task specific ILs. © 2015 American Institute of Chemical Engineers AIChE J, 62: 264–274, 2016 相似文献
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Adam J. Hepburn Andrew J. Daugulis 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2012,87(1):42-50
BACKGROUND: Succinic acid (SA) is an intermediate in the production of commodity chemicals, but SA bioproduction has not yet been commercialized due to end product inhibition and high product separation costs. Two‐phase partitioning bioreactors (TPPBs) can increase volumetric productivity through in situ product removal, although SA uptake by polymers requires a pH below the pKA2 of SA (4.2). It was proposed to reversibly reduce the pH with CO2 sparging for absorption of SA, followed by nitrogen stripping to allow continued bioproduction after returning to metabolic pH levels. RESULTS: At 1 atm CO2 sparging lowered the pH of RO water to 3.8 but only to 4.75 in medium, requiring acid/base pH adjustment in subsequent experiments. Actinobacillus succinogenes was temporarily exposed to pH 4.2 for between 5 min and 4 h to observe the effect on subsequent growth; cells could grow after up to 4 h of low pH exposure, sufficient time for SA uptake. Because atmospheric CO2 could not adequately lower the pH of medium, a TPPB was operated with the pH being shifted using strong acid/base; SA was recovered in situ, however, the accumulation of salts hindered further cell growth. CONCLUSION: Several key elements of this novel processing strategy were successfully demonstrated, and work is continuing with high pressure CO2 to achieve the desired pH adjustment levels. Copyright © 2011 Society of Chemical Industry 相似文献
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Murni M. Ahmad Steinar Hauan Todd M. Przybycien 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2010,85(12):1575-1587
BACKGROUND: Aqueous two‐phase extraction (ATPE) has many advantages as an efficient, inexpensive large‐scale liquid–liquid extraction technique for protein separation. However, the realization of ATPE as a protein separation technology at industrial scales is rather limited due to the large, multidimensional design space and the paucity of design approaches to predict phase and product behavior in an integrated fashion with overall system performance. This paper describes a framework designed to calculate suitable flowsheets for the extraction of a target protein from a complex protein feed using ATPE. The framework incorporated a routine to set up flowsheets according to target protein partitioning behavior in specific ATPE systems and a calculation of the amounts of phase‐forming components needed to extract the target protein. The thermodynamics of phase formation and partitioning were modeled using Flory‐Huggins theory and calculated using a Gibbs energy difference minimization approach. RESULTS: As a case study, suitable flowsheets to recover phosphofructokinase from a simple model feedstock using poly(ethylene glycol)‐dextran (PEG6000‐DxT500) and poly(ethylene glycol)‐salt (PEG6000‐Na3PO4) two‐phase systems were designed and the existence of feasible solutions was demonstrated. The flowsheets were compared in terms of product yield, product purity, phase settling rate and scaled process cost. The effect of the mass flowrates of phase‐forming components on product yield and purity was also determined. CONCLUSION: This framework is proposed as a basis for flowsheet optimization for protein purification using ATPE systems. Copyright © 2010 Society of Chemical Industry 相似文献
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Jian‐Hang Zhu Dong‐Zhi Wei Xue‐Jun Cao Ye‐Qing Liu Zhong‐Yi Yuan 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2001,76(11):1194-1200
In order to develop an aqueous two‐phase system (ATPS) for cephalexin synthesis with extractive bioconversion, the partitioning behaviour of cephalexin and 7‐aminodeacetoxicephalosporanic acid (7‐ADCA) in poly(ethylene glycol) (PEG)/salt ATPS were examined. Parameters such as PEG size, salt type and tie line length were investigated to find a primary extraction system. In PEG400/ammonium sulfate and PEG400/magnesium sulfate systems, the partition coefficient of cephalexin (KC) was larger than 1 while that of 7‐ADCA (KA) deviated about 1.5. Addition of neutral salts, surfactants and water‐miscible solvents were also investigated in the primary ATPS in order to improve the separation efficiency. KC greatly increased when neutral salts and surfactants were added to the PEG400/ammonium sulfate primary systems whereas KA was only slightly higher than that of the additive‐free ATPS. In an improved ATPS for extractive bioconversion, consisting of PEG400 (20% w/w), ammonium sulfate (17.5% w/w), methanol (5% w/w) and NaCl (3% w/w), a KC value of up to 15.2 was achieved; KA was 1.8; KP (partition coefficient of phenylglycine methyl ester) was 1.2 and the recovery yield of cephalexin was 94.2%. The results obtained from the extractive bioconversion of cephalexin in the improved ATPS showed that it is feasible to perform such an enzymatic process in an ATPS and the system offers the potential as a model for enzymatic synthesis of some water soluble products. © 2001 Society of Chemical Industry 相似文献
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Patrick B. Smith Walter C. Buzanowski Judy J. Gunderson Duane B. Priddy Lance Pfenninger 《应用聚合物科学杂志》2001,82(8):1963-1970
The phase partitioning of additives in polymer blends has a large impact on the performance of the blend. Therefore, it is necessary to be able to quantify the level of the additives in each phase. A 1H–NMR method is presented to determine the partitioning of additives between the rubber and rigid phases of a high‐impact polystyrene (HIPS) material. In one case, a HIPS material was modified with 2,6‐di‐tert‐butyl‐4‐methyl‐phenol (Ionol, CAS# 128‐37‐OMF) as a stabilizer for both phases. HIPS materials with varying levels of Ionol were melt‐blended by extrusion and the total level of additives was determined analytically for these standard materials. The 1H–NMR method was used to determine the level of Ionol in the poly(butadiene) rubber phase. The Ionol was found to preferentially partition into the rubber phase with a partition coefficient of about 2. A second example of the same concept, instead utilizing 13C–NMR, involved the analysis of the partition coefficient for both Tinuvin P and Tinuvin 770 (CAS# 2440‐22‐4 and 52829‐07‐9), partitioning between the rigid and rubber phases of an ethylene–propylene–diene‐modified (EPDM) toughened styrene–ran–acrylonitrile (SAN) copolymer. The partition coefficient was determined to be 0.5 for Tinuvin P and 1.3 for Tinuvin 770. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1963–1970, 2001 相似文献
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Tobias Vallon Matthias Glemser Dr. Sumire Honda Malca Dr. Daniel Scheps Dr. Joachim Schmid Dr. Martin Siemann‐Herzberg Prof. Dr. Bernhard Hauer Prof. Dr. Ralf Takors 《化学，工程师，技术》2013,85(6):841-848
A two‐phase biotransformation process for selective hydroxylation of n‐octane to 1‐octanol via Pseudomonas putida KT2440 harboring heterologously expressed P450 monooxygenase from Mycobacterium marinum is presented. Maximum cell‐specific conversion rates of 12.7 mgoctanol gCDWh–1 were observed not only in shaking flasks but also in 3.7‐L‐bioreactor studies. The bioreactor experiments were performed avoiding explosive gas mixtures by lowering volumetric power input, aeration rates and substrate concentrations. Based on a stoichiometric network of P. putida KT2440 topological studies were carried out. As a conclusion, potential limitations of NAD(P)H and/or ATP supply at production conditions can be excluded. Hence, the great potential of the host for further increasing conversion is outlined. 相似文献
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Settu Saravanan Jonnalagadda Raghava Rao Thanapalan Murugesan Balachandran Unni Nair Thirumalachari Ramasami 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2006,81(11):1814-1819
Leather processing involves discharge of high‐value soluble globular proteins in the wastewater. The recovery of value‐added products from the wastewaters is gaining more importance in the context of recovery of wealth from waste. The recovery of these globular proteins from tannery wastewater was selected as a practical model system to study the implementation of polyethylene glycol (PEG)‐sulfate aqueous two‐phase systems (ATPS). The partition coefficient of bovine serum albumin is comparable to that of soluble proteins from tannery wastewaters. The influence of concentration of polymer, salt, pH and temperature on the partitioning of soluble proteins from tannery wastewaters has been studied. The PEG6000 + sodium sulfate + water system provide better partitioning of these soluble proteins as compared to PEG6000 + ammonium sulfate system. The maximum protein recovery yield for PEG6000 + sodium sulfate + water system at 20 °C is 92.75%. The influence of temperature indicates the recovery of proteins from tannery wastewater to be better at lower temperature. The findings of these studies raise the potential application of ATPS processes for protein recovery from complex biological systems. Copyright © 2006 Society of Chemical Industry 相似文献