Kinetics and performance of a co-immobilised system of amyloglucosidase and Zymomonas mobilis

High operational stability and productivity of co-immobilised systems are important aspects for their successful application in industrial processes. A dynamic model is required to describe artificially co-immobilised systems because the time needed to reach steady state normally exceeds the operati...

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Bibliographic Details
Published in:	Biotechnology and bioengineering Vol. 63; no. 6; pp. 694 - 704
Main Authors:	Hellendoorn, L, Ottengraf, S.P.P, Heuvel, J.C. van den, Pennings, J.A.M.M, Santos, V.A.P.M. dos, Wijiffels, R.H
Format:	Journal Article
Language:	English
Published:	New York John Wiley & Sons, Inc 20-06-1999 Wiley
Subjects:	amyloglucosidase Biocatalysts Bioconversion Biological and medical sciences Biomass Biotechnology Biotechnology - methods co-immobilised systems Coimmobilization Computer simulation dynamic modelling Enzyme inhibition Enzymes, Immobilized - chemistry Enzymes, Immobilized - metabolism Ethanol Ethanol - metabolism Fundamental and applied biological sciences. Psychology glucan 1,4-alpha-glucosidase Glucan 1,4-alpha-Glucosidase - chemistry Glucan 1,4-alpha-Glucosidase - metabolism Glucose Growth kinetics immobilization Immobilization techniques Kinetics Mathematical models Methods. Procedures. Technologies Models, Biological Polyethylenes stability Zymomonas - enzymology Zymomonas mobilis Productivity Glucan 1,4-α-glucosidase Stability Ethanol Enzyme Coimmobilization Immobilization Maltose Optimization Glycosidases Production Bacteria Hydrolases Kinetics Mathematical model Immobilized enzyme Entrapped microorganism Zymomonas mobilis
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Summary:	High operational stability and productivity of co-immobilised systems are important aspects for their successful application in industrial processes. A dynamic model is required to describe artificially co-immobilised systems because the time needed to reach steady state normally exceeds the operational life span of these systems. Time dependent intraparticle concentration profiles and macroscopic conversion were modelled to study the operational stability and productivity of these systems theoretically. The model was used to describe experimental results of ethanol production from maltose by a co-immobilised system of amyloglucosidase and Zymomonas mobilis. Furthermore, the influence of the immobilisation procedure with glutaraldehyde and polyethyleneimine could also be studied with and incorporated in the model. From the model it could be derived that co-immobilised systems performing a consecutive reaction evolve towards a steady state, characterised by a constant concentration of the intermediate in the particle if product inhibition is neglected. Such a situation develops independently of the biomass concentration and the radial position, and has important consequences for co-immobilised systems. When the concentration of the intermediate in the bulk liquid is lower than this constant value in the biocatalyst particle, two regions may be distinguished in the particle: an inactive peripheral region without biomass and an active core with a biomass concentration depending on the substrate and immobilised enzyme concentration. Unlike immobilised single cell systems, it is possible to obtain a real steady state and therefore a stable situation for co-immobilised systems. However, a high operational life time could only be achieved at the expense of the productivity of the biocatalyst particle. A stability criterion is derived which agrees very well with the simulation results.
Bibliography:	istex:4F8CCC780BC756D88218CDCEB624F89CCBC6E8F4 ark:/67375/WNG-5R80LN1L-V ArticleID:BIT7 ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 ObjectType-Article-1 ObjectType-Feature-2
ISSN:	0006-3592 1097-0290
DOI:	10.1002/(SICI)1097-0290(19990620)63:6<694::AID-BIT7>3.0.CO;2-M