Abstract
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.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.