Automation of an experimental system for the microbial epoxidation of propene and 1-butene

Brink, L.E.S.; Tramper, J.; Riet, K. van ’t; Luyben, K. Ch. A. M.

doi:10.1016/s0003-2670(00)81509-3

Cited by 16 publications

(3 citation statements)

References 6 publications

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“…However, a benefit of using calcium alginate as an immobilization matrix is its high water content. The high water content surrounding the cells can help retain activity, but the hydrophilicity of the gel however leads to low diffusion rates, especially for hydrophobic substrates (35, 14). These low diffusion rates then lead to lower reaction rates.…”

Section: Resultsmentioning

confidence: 99%

Microbial Oxidation of Naphthalene to cis‐1,2‐Naphthalene Dihydrodiol Using Naphthalene Dioxygenase in Biphasic Media

McIver

Garikipati

Bankole

et al. 2008

Biotechnology Progress

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The selective oxidation of aryl substrates to chiral cis‐1,2‐dihydrodiols is an industrially important reaction for the production of intermediates that can be used to produce fine chemicals, pharmaceuticals, and many other bioactive natural products. More specifically, the oxidation of naphthalene to produce optically pure (+)‐ cis‐(1 R,2 S)‐1,2‐napthalene dihydrodiol (NDHD) to be used as a chiral synthon for specialty chemicals has gained much interest. Escherichia coli JM109(DE3) pDTG141 expresses naphthalene dioxygenase which catalyzes this reaction. Poor substrate solubility and substrate toxicity are barriers to using the power of these enzymes in large‐scale aqueous whole cell systems. A biphasic reaction system was chosen to overcome these barriers. The optimal biphasic conditions for E. coli JM109(DE3) pDTG141 were determined to be 20% dodecane as the organic solvent containing 40 g/L naphthalene. The productivity of the biotransformation using resting cells was 1.75 g‐diol/g‐cdw/h for the first 6 h with 20% organic phase, which was increased from 0.59 g‐diol/g‐cdw/h for growing cells with 40% organic phase. The biocatalytic activity was retained for at least 12 h. The biocatalyst could be recycled for at least four runs in both suspended and immobilized form. The stability of the 12 h recycle was improved by immobilization in calcium alginate beads. The process has been improved both environmentally and economically by reducing the amount of solvent used and by recycling the biocatalyst.

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Section: Resultsmentioning

confidence: 99%

Microbial Oxidation of Naphthalene to cis‐1,2‐Naphthalene Dihydrodiol Using Naphthalene Dioxygenase in Biphasic Media

McIver

Garikipati

Bankole

et al. 2008

Biotechnology Progress

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“…When the experiments with immobilized cells were performed with larger particles and/or higher cell loads, lower reaction rates were measured as a result of these diffusion limitations. 16,22 As the reaction proceeds, an increasing difference is found between experimental epoxide concentrations and calculated values from alkene consumption rates.I6 Hydrolysis of the produced propene oxide to 1,2-propanediol cannot explain the difference. Literature values'' (2.3 x lop6 s-') as well as experimentally determined values (1.5 x s-') of the first-order reaction constant for hydrolysis at the experimental conditions used (30°C, pH -6) are an order of magnitude too small to explain this discrepancy.…”

Section: Generalmentioning

confidence: 99%

Optimization of organic solvent in multiphase biocatalysis

Brink

Tramper

1985

Biotech & Bioengineering

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253

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The microbial epoxidation of propene and 1-butene was used to study some fundamental aspects of two-liquid-phase biocatalytic conversions. Introduction of a water-immiscible organic solvent phase in a free-cell suspension gave rise to a series of undesired phenomena, e.g., inactivation by the solvent, clotting of biomass, and aggregation of cells at the liquid-liquid interface. Immobilization of the cells in hydrophilic gels, e.g., calcium alginate, prevented direct cell-organic solvent contact and the related clotting and aggregation of biomass. However, the gel entrapment did not seem to provide additional protection against the organic solvent. The influence of various organic solvents on the retention of immobilized-cell activity was related to solvent properties like the polarity (as expressed by the Hildebrand solubility parameter) and the molecular size (as expressed by the molecular weight or molar volume). High activity retention was favored by a low polarity in combination with a high molecular weight. The solubility parameter also proved useful to describe the capacity of various organic solvents for oxygen and alkene oxides. This facilitated the optimization of the solvent polarity.

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“…Propene and oxygen-consumption rates of the gel-entrapped cells in the packed-bed reactor were measured by on-line gas chromatographic analysis of the gaseous substrates in the circulating gas stream as described p r e v i~u s l y .~~ The concentrations of the substrates in the organic or aqueous reactor-inlet stream in equilibrium with the gas phase could then be calculated using Henry's law. 43 The on-line gas chromatograph was coupled to an integrator and a microcomputer. This enabled automatic operation of the gas-sampling valve in conjunction with a column-switching ~a l v e .~~,~~ Besides data acquisition and reduction, the coupling to the computer also made it possible to control the concentrations of the two substrates in the gas phase and, consequently, in the reactor-inlet stream by computer-controlled addition of the gaseous substrates.…”

Section: Packed-bed Reactor Systemmentioning

confidence: 99%

Facilitated mass transfer in a packed‐bed immobilized‐cell reactor by using an organic solvent as substrate reservoir

Brink

Tramper

1987

J of Chemical Tech & Biotech

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A B S T R A C TThe production of propene oxide f r o m propene and oxygen by nongrowing cells entrapped in calcium alginate was used to study the behaviour of a packed-bed immobilized-cell reactor operated with an organic solvent as the substrate reservoir. As a result of the high solubility of propene in the solvent used, n-hexadecane, oxygen was considered to be the limiting substrate. Dilution of the biocatalyst bed with small glass particles appeared necessary to attain a high liquidlsolid contacting efficiency between the hydrophilic gel particles and the hydrophobic solvent. The bed dilution had the advantage of avoiding bed compaction and reducing pressure drops. The use of an organic Solvent as the transport medium prevented oxygen depletion along the length of the packed-bed reactor. This eliminated the need for a separate gas phase in the bioreactor. A mathematical reactor model was developed to describe the combined effects of contacting pattern and external and internal diffusion limitations on the instrinsic kinetics of the immobilized cells. Experiments with the packed-bed immobilized-cell reactor were performed using an aqueous solution or n-hexadecane as the reaction medium. Predicted oxygen conversions compared favourably to the observed values without the need f o r fitting factors.

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Automation of an experimental system for the microbial epoxidation of propene and 1-butene

Cited by 16 publications

References 6 publications

Microbial Oxidation of Naphthalene to cis‐1,2‐Naphthalene Dihydrodiol Using Naphthalene Dioxygenase in Biphasic Media

Microbial Oxidation of Naphthalene to cis‐1,2‐Naphthalene Dihydrodiol Using Naphthalene Dioxygenase in Biphasic Media

Optimization of organic solvent in multiphase biocatalysis

Facilitated mass transfer in a packed‐bed immobilized‐cell reactor by using an organic solvent as substrate reservoir

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