Bioprocess and Biosystems Engineering

, Volume 31, Issue 5, pp 493–498

Semi-continuous xylose-to-xylitol bioconversion by Ca-alginate entrapped yeast cells in a stirred tank reactor

  • Walter Carvalho
  • Larissa Canilha
  • Silvio S. Silva
Original Paper

DOI: 10.1007/s00449-007-0187-z

Cite this article as:
Carvalho, W., Canilha, L. & Silva, S.S. Bioprocess Biosyst Eng (2008) 31: 493. doi:10.1007/s00449-007-0187-z

Abstract

Candida guilliermondii FTI 20037 cells were entrapped in Ca-alginate beads and used for xylose-to-xylitol bioconversions during five successive batches in a stirred tank reactor. Supplemented sugarcane bagasse hemicellulosic hydrolysate was used as the fermentation medium. The average volume of the Ca-alginate beads was reduced by about 30% after the 600 h taken to perform the five bioconversion cycles, thus demonstrating physical instability under the conditions prevailing in the reactor vessel. In spite of this, almost steady bioconversion rates and yields were observed along the repeated batches. In average values, a production of 51.6 g l−1, a productivity of 0.43 g l−1 h−1 and a yield of 0.71 g g−1 were attained in each batch, variation coefficients being smaller than 10%.

Keywords

Sugarcane bagasse hemicellulosic hydrolysateXylitolCa-alginate entrapped cellsSemi-continuous fermentation

List of symbols

D

diameter of the Ca-alginate beads (mm)

P

xylitol concentration (g l−1)

QP

xylitol productivity [QP = P/t] (g l−1)

S

xylose concentration (g l−1)

t

fermentation time (h)

V

volume of individual Ca-alginate beads (mm3)

VI

volume of Ca-alginate beads in the reactor (l)

VM

volume of fermentation medium in the reactor (l)

VR

volume of reactor [V= V+ VM] (l)

XI

concentration of immobilized cells in the Ca-alginate beads (g l−1)

XM

concentration of free cells in the fermentation medium (g l−1)

XR

concentration of cells in the reactor (g l−1)

XRI

concentration of immobilized cells in the reactor (g l−1)

XRI%

percentage of immobilized cells in the reactor (%)

XRM

concentration of free cells in the reactor (g l−1)

YP/S

xylose to xylitol bioconversion yield [YP/S = ΔP/ − ΔS] (g g−1)

μP

specific rate of xylitol production (g g−1 h−1)

μS

specific rate of xylose consumption (g g−1 h−1)

μXR

specific rate of cell growth (h−1)

μXRI

specific rate of immobilized cell growth (h−1)

μXRM

specific rate of free cell growth (h−1)

Copyright information

© Springer-Verlag 2007

Authors and Affiliations

  • Walter Carvalho
    • 1
  • Larissa Canilha
    • 1
  • Silvio S. Silva
    • 1
  1. 1.Departamento de BiotecnologiaEscola de Engenharia de LorenaLorenaBrazil