Bioreactor biphasic

In 1982, Lilly [21] reviewed the first two-liquid phase biocatalysis. In 1987 and 1992, Lilly s group [39,40] published reviews dealing with process engineering of biphasic bioreactors. In 1993, Van Sonsbeek et al. [41] gave an overview on biocatalysis in different biphasic... 

On the other hand, biocatalyst stability can be affected by the presence of organic-aqueous interface. In our previous work [25], we studied the effect of interface with octane on the lipoxygenase stability in an octane-buffer pH 9.6 biphasic system. This loss in activity is more pronounced than that observed in the aqueous system. During lipoxygena-tion, the active enzyme concentration [E] in the aqueous phase of our biphasic bioreactor was ... 

Various criteria can influence the choice of organic solvent that can be used in a biphasic bioreactor degree of solubility of substrates and/or products, inactivation effect, toxicity, flammability, and essentially reactant partition between the phases. Much research has been carried out on this topic [7,8,14,15,33,67]. 

In the biphasic bioreactor, we found that the presence of octane causes an inactivation of lipoxygenase dissolved in the aqueous phase [Eq. (1)]. This loss in activity is more pronounced than that observed in the aqueous system. 

Many interesting biocatalytic reactions involve organic components that are poorly water-soluble. When using organic-aqueous biphasic bioreactor, availability of poorly water-soluble reactants to cells and enzymes is improved, and product extraction can be coupled to the bioreaction. Many applications in two-phase media can use the existing standard-type bioreactors, such as stirred-tank, fluidized-bed, and column reactors with minor adjustments. 

This chapter shows how a biphasic medium can help in reducing loss of volatile compounds in a gaseous phase exiting from a bioreactor, in comparison with pure aqueous systems. It also emphasises the usefulness of solvents having low vapour pressure (heavy organic solvents or ionic liquids) in the reduction of the release of compounds into the environment. There are, from this point of view, common interests between engineering needs and environmental concerns in the flavouring industry. 

One of the major disadvantages of using these enzymes to reduce ketones is generally the very poor aqueous solubility of the substrates (usually <5-10 mM) and the fact that the co-factor regeneration system is sensitive to organic solvents. To address this limitation, biphasic and membrane bioreactors have been used that allow for moderate to high conversions with often >99% ee for selected products. This has been demonstrated with the (.S )-Adi I from Rhodococcus erythropolis,36-37... 

In biphasic reactors or two-phase partitioning bioreactors (TPPB), the substrate is located mostly in the immiscible phase and diffuses to the aqueous phase. The enzyme catalyzes conversion of the substrate at the interface and/or in the aqueous phase. The product/s of the reaction then may partition to the organic phase. The system is self-regulated, as the substrate delivery to the aqueous phase is only directed by the partitioning ratio between the two phases and the enzymatic reaction rate [53]. The use of ionic liquid/supercritical carbon dioxide for enzyme-catalyzed transformation is gaining attention [69]. 

Isono Y, Nakajima M (2000) Membrane phase separation of aqueous/alcohol biphase mixture and its application for enzyme bioreactor. Prog Biotechnol 2000 63-68... 

Several authors have demonstrated the capability of enzymes to catalysing reaction in scCO /IL biphasic systems [34,37,38]. The synthesis of butyl propionate, which is a flavour agent, was successfully carried out in a recirculating bioreactor in scCOj/IL biphasic systems at 50°C and 80 bars [38]. This reactor was made from stainless steel (internal volume=178 mL) equipped with valves, pressure and flow... 

Production of an optically active diltiazem intermediate (2R, 3S)-methoxyophenylglyci-date methyl ester ((-)-MPGM) from racemic MPGM by the action of lipase from Serratia marcescens in a toluene aqueous biphasic system (Tanabe Seiyaku Co., Ltd.). For the continuous production of (-)-MPGM, a hollow fiber bioreactor was set up in collaboration with Sepracor Inc. The introduction of this enzymatic step allowed the shortening of the diltiazem synthesis from nine down to five steps. 

The production of other profens as well, like the enantiospecific esterification of racemic ketoprofen in non-aqueous solvent under reduced pressure (De Crescenzo et al. 2000 Ong et al. 2005) and the anti-inflammatory drug naproxen by kinetic resolution of the racemic ester in a in an aqueous-organic biphasic system in a stirred tank membrane bioreactor (Xin et al. 2001)... 

Isono Y, Nakajima M (2000) Membrane phase separation of aqueous/alcohol biphase mixture and its application for enzyme bioreactor. Prog Biotechnol 16 63-68 Jaspers CJ, Jimenez G, Penninckx MJ (1994) Evidence for a role of manganese peroxidase in the decolorization of Kraft pulp bleach plant effluent by Phanerochaete chrysosporium effects of initial culture conditions on enzyme production. J Biotechnol 37(3) 229-234 Johannes C, Majeherezyk A, Huttermaim A (1996) Degradation of anthracene by laccase ofTram-etes versicolor in the presence of different mediator compounds. Appl Microbiol Biotechnol 46(3) 313-317... 

Conversion (o) ee (ee of substrate). Reaction was performed in a 2 L bioreactor at 30 °C and 200 rpm using an isopropyl ether-water biphasic system with 100 mM ( )-MPGM and 900 U of chitosan-SmL. The pH was automatically controlled at 8.0-8.3 hy titrating 2% ammonia. The immobilized lipase was reused in new reactions after ee of the last run reached 99.9%. From the 7 batch of reaction, 15 g of fresh immobilized lipase (corresponding to io% of the initial amount, ca. 90 U) was supplemented at the beginning of each reaction cycle. After the 12 batch of reaction, 15 g of used immobilized lipase was substituted by 15 g of fresh lipase (ca. 90 U). The partial renewal of the immobilized biocatalyst was continued for 10 cycles (12 -21 ). 

Deng, H.-T., Xu, Z.-K., Dai, Z.-W., Wu, J. and Seta, P. 2005. Immobilization of Candida rugosa lipase on polypropylene microfiltration membrane modified by glycopolymer Hydrolysis of olive oil in biphasic bioreactor. 

Other interesting appUcations regard (S)-Naproxen through biphasic EMRs. In these cases, the presence of the emulsion combined with the enzyme bioreactor improves the catalytic activity and enantiose-lectivity of the immobilized enzyme, along with the mass transfer of the hydrophobic reagent (Naproxen esters and triglycerides) note that the immobilization procedure preserves enzyme stability without altering its enantioselectivity. 

The synthesis of butyl propionate in a recirculating bioreactor was carried out in an IL/supercritical carbon dioxide biphasic system at 50°C and 80 bar using immobilized C. antarctica lipase B (Figure 3.27) [37]. Selectivity increased (reaching more than 99.5%) when the ionic liquid/snpercritical carbon dioxide biphasic systems were nsed rather than supercritical carbon dioxide alone. 

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