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Chitosan flocculation: An effective method for immobilization of E. coli for biocatalytic processes

Paper ID Volume ID Publish Year Pages File Format Full-Text
23523 43446 2013 7 PDF Available
Title
Chitosan flocculation: An effective method for immobilization of E. coli for biocatalytic processes
Abstract

•E. coli cells containing ω-transaminase were immobilized using chitosan flocculation.•Minimal diffusion limitations despite very high loading of immobilized cells.•Reusability was demonstrated in five batches producing (S)-4′-α-cyano-methylbenzylamine.•Floc characteristics can be altered by varying the cell to chitosan ratio.•Simple and effective immobilization method using a low cost material.

Immobilization of Escherichia coli cells containing a ω-transaminase was carried out by flocculation with chitosan and the preparation was used in asymmetric synthesis of (S)-4′-cyano-α-methylbenzylamine, recycled in five consecutive batches. Chitosans with different molecular weights and degrees of acetylation were compared and effects of varying the chitosan properties, cell concentration and ratio of cells to chitosan were studied.Immobilization was achieved by increasing the pH to slightly alkaline, which induced the formation of large fast sedimenting flocs. Although an effective immobilization was obtained using most types of chitosan, high molecular weight and low degree of acetylation were considered favourable properties, resulting in good floc stability and quick sedimentation. It was found that it was possible to affect the floc characteristics, by changing the ratio of cells to chitosan in such a way that preparations resembling either entrapped or cross-linked cells could be obtained. The volume of the sedimented preparation decreased approximately 50% when increasing the cell to chitosan ratio from 2 g/g to 10 g/g at a constant amount of cells. Despite very high concentrations of cells (10–100 g cells/g chitosan) in the flocculated preparations, diffusion limitations were minimal. Flocculation with chitosan was considered a simple and effective method for immobilization of E. coli cells for biocatalytic processes.

Keywords
Chitosan; Immobilization; Flocculation; ω-Transaminase; Asymmetric synthesis; Chiral amines
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Chitosan flocculation: An effective method for immobilization of E. coli for biocatalytic processes
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Publisher
Database: Elsevier - ScienceDirect
Journal: Journal of Biotechnology - Volume 165, Issue 2, 20 May 2013, Pages 138–144
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us