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

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Chitosan flocculation: An effective method for immobilization of E. coli for biocatalytic processes. / Rehn, Gustav; Grey, Carl; Branneby, Cecilia; Adlercreutz, Patrick.

I: Journal of Biotechnology, Vol. 165, Nr. 2, 2013, s. 138-144.

Forskningsoutput: TidskriftsbidragArtikel i vetenskaplig tidskrift

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TY - JOUR

T1 - Chitosan flocculation: An effective method for immobilization of E. coli for biocatalytic processes.

AU - Rehn, Gustav

AU - Grey, Carl

AU - Branneby, Cecilia

AU - Adlercreutz, Patrick

PY - 2013

Y1 - 2013

N2 - 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 2g/g to 10g/g at a constant amount of cells. Despite very high concentrations of cells (10-100g 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.

AB - 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 2g/g to 10g/g at a constant amount of cells. Despite very high concentrations of cells (10-100g 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.

U2 - 10.1016/j.jbiotec.2013.03.014

DO - 10.1016/j.jbiotec.2013.03.014

M3 - Article

VL - 165

SP - 138

EP - 144

JO - Journal of Biotechnology

T2 - Journal of Biotechnology

JF - Journal of Biotechnology

SN - 1873-4863

IS - 2

ER -