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Applied Microbiology and Biotechnology

, Volume 46, Issue 3, pp 240–249 | Cite as

Uptake of lactose and continuous lactic acid fermentation by entrapped non-growing Lactobacillus helveticus in whey permeate

  • J. Øyaas
  • I. Storrø
  • D. W. Levine
ORIGINAL PAPER

Abstract

 Continuous production of lactic acid from lactose has been carried out in a stirred-tank reactor with non-growing Lactobacillus helveticus entrapped in calcium alginate beads. A considerably longer operation half-life was obtained in a continuously operated reactor than in a batch-operated reactor. It is possible to simulate the action of entrapped non-growing cells on the basis of information from diffusion and kinetic experiments with suspended free cells. The simulation fit the experimental data over a broad range of substrate concentrations if the specific lactic acid production rate, qP, was used as a variable parameter in the model. The dynamic mathematical model used is divided into three parts: the reactor model, which describes the mass balance in a continuously operated stirred-tank reactor with immobilized biomass, the mass-transfer model including both external diffusion and internal mass transfer, and the kinetic model for uptake of substrate on the basis of a Michaelis-Menten-type mechanism. From kinetic data obtained for free biomass experiments it was found, with the use of non-linear parameter estimation techniques, that the conversion rate of lactose by L. helveticus followed a Michaelis-Menten-type mechanism with KS at half-saturation=0.22±0.01 g/l. The maximum specific lactose uptake rate for growing cells, qS,max, varied between 4.32±0.02 g lactose g cells-1 h-1 and 4.89 ±0.02 g lactose g cells-1 h-1. The initial specific lactose uptake rate for non-growing cells, qS,0, was found to be approximately 40% of the maximum specific lactose uptake rate for growing cells.

Keywords

Lactic Acid Lactose Alginate Calcium Alginate Lactic Acid Production 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag Berlin Heidelberg 1996

Authors and Affiliations

  • J. Øyaas
    • 1
  • I. Storrø
    • 2
  • D. W. Levine
    • 1
  1. 1.Department of Biotechnology, Norwegian Institute of Technology, 7034 Trondheim, NorwayNO
  2. 2.SINTEF, Applied Chemistry, 7034 Trondheim, Norway. Fax: 47 73596995NO

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