Microemulsions have been considered as adequate media for carrying out bioconversions however, their use is limited by the difficulty in isolating products due to the presence of surfactants that hinder phase separation. Nevertheless, microemulsions can be transformed to gels by adding a gelling agent mainly biopolymer such as cellulose derivatives [1], to form the so-called microemulsion-based organogels (MBGs). MBGs are rigid and stable in various non-polar or relatively polar organic solvents, and enzymes immobilized in such media maintain their catalytic activity and stability for long periods [2], therefore, MBGs can be used for the catalysis of interesting synthetic reactions with great biotechnological interest.
In the present work C. antarctica and R. miehei lipases were immobilized in hydroxyl-propyl-methyl cellulose (HPMC)- MBGs and used for the synthesis of various high added value products under continuous flow conditions. For this purpose, two continuous flow systems have been used based on packed bed reactors: one commercial for the production of monoacylglycerides, and one home-build for the production of lipid and phenolic esters as well as terpene alcohol esters. In all cases, high productivities were obtained as compared to analogue batch reactions. Moreover, the study on the reuse of the system showed that it can be reused 15 times without activity loss, a number two fold higher than for immobilized lipases in batch conditions.
[1] C. Delimitsou, M. Zoumpanioti, A. Xenakis, H. Stamatis (2002) Biocatal. Biotransform. 20, 319.
[2] M. Zoumpanioti, H. Stamatis, A. Xenakis (2010) Biotechnol. Advances, 28, 395.
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