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Xylitol production by immobilized recombinant Saccharomyces cerevisiae in a continuous packed-bed bioreactor

Roca, E. (University of Santiago de Compostela, Santiago de Compostela, Spain.) ; Meinander, N ; Hahn-Hagerdal, B

Biotechnology and bioengineering, 1996-08, Vol.51 (3), p.317-326 [Periódico revisado por pares]

Hoboken: Wiley Subscription Services, Inc., A Wiley Company

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  • Título:
    Xylitol production by immobilized recombinant Saccharomyces cerevisiae in a continuous packed-bed bioreactor
  • Autor: Roca, E. (University of Santiago de Compostela, Santiago de Compostela, Spain.) ; Meinander, N ; Hahn-Hagerdal, B
  • Assuntos: Biological and medical sciences ; Biotechnology ; continuous packed-bed reactor ; Fundamental and applied biological sciences. Psychology ; immobilization ; Methods. Procedures. Technologies ; Microbial engineering. Fermentation and microbial culture technology ; recombinant yeast ; SACCHAROMYCES CEREVISIAE ; xylitol
  • É parte de: Biotechnology and bioengineering, 1996-08, Vol.51 (3), p.317-326
  • Notas: 9731986
    F60
    ArticleID:BIT7
    Spanish Commission of Science and Technology, Spanish Govt. - No. BI092 0568
    istex:61A8FDB956BA6F779BAA6C70C87A9290F7754BFC
    Knut and Alice Wallenberg Foundation
    Swedish Ethanol Development Foundation (SSEU)
    Nordiz Industrial Fund (NIF)
    Swedish Natural Science Research Council
    ark:/67375/WNG-2W22B26W-B
    National Swedish Board for Technical Development (NUTEK)
    ObjectType-Article-2
    SourceType-Scholarly Journals-1
    ObjectType-Feature-1
    content type line 23
    ObjectType-Article-1
    ObjectType-Feature-2
  • Descrição: Continuous xylitol production with two different immobilized recombinant Saccharomyces cerevisiae strains (H475 and S641), expressing low and high xylose reductase (XR) activities, was investigated in a lab-scale packed-bed bioreactor. The effect of hydraulic residence time (HRT; 1.3-11.3 h), substrate/cosubstrate ratio (0.5 and 1), recycling ratio (0, 5, and 10), and aeration (anaerobic and oxygen limited conditions) were studied. The cells were immobilized by gel entrapment using Ca-alginate as support and the beads were treated with Al(3+) to improve their mechanical strength. Xylose was converted to xylitol using glucose as cosubstrate for regeneration of NAD(P)H required in xylitol formation and for generation of maintenance energy. The stability of the recombinant strains after 15 days of continuous operation was evaluated by XR activity and plasmid retention analyses. Under anaerobic conditions the volumetric xylitol productivity increased with decreasing HRT with both strains. With a recycling ratio of 10, volumetric productivities as high as 3.44 and 5.80 g/L.h were obtained with the low XR strain at HRT 1.3 h and with the high XR strain at HRT 2.6 h, respectively. However, the highest overall xylitol yields on xylose and on cosubstrate were reached a higher HRTs. Lowering the xylose/cosubstrate ratio from 1 to 0.5 increased the overall yield of xylitol on xylose but the productivity and the xylitol yield on cosubstrate decreased. Under oxygen limited conditions the effect of the recycling ratio on production parameters was masked by other factors, such as an accumulation of free cells in the bioreactor and severe genetic instability of the high XR strain. Under anaerobic conditions the instability was less severe, causing a decrease in XR activity from 0.10 to 0.10 and from 3.18 to 1.49 U/mg with the low and high XR strains, respectively
  • Editor: Hoboken: Wiley Subscription Services, Inc., A Wiley Company
  • Idioma: Inglês
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