• Log In
  • New issue alert
  • Submit a manuscript
  • Register
  • Home
  • About
  • Editorial Board
  • Search
  • Archives
  • Current
  • Forthcoming

Share

Article Panel


Vol 10, No 2 (2007)
»Table of Contents
Reading Tools
  • About the author
  • How to cite this article
  • Indexing metadata
  • Print version
  • Look up terms
  • Finding References
  • Review policy

Related items
  • Author's work


Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivatives 4.0 International.
Fermentation technologies for the production of exopolysaccharide-synthesizing Lactobacillus rhamnosus concentrated cultures | Champagne | Electronic Journal of Biotechnology
doi: 10.2225/vol10-issue2-fulltext-10
Electronic Journal of Biotechnology, Vol 10, No 2 (2007)

Fermentation technologies for the production of exopolysaccharide-synthesizing Lactobacillus rhamnosus concentrated cultures

Claude P. Champagne, Nancy J. Gardner, Christophe Lacroix



Abstract

The exopolysaccharide (EPS)-producing cultures such as Lactobacillus rhamnosus RW-9595M present a challenge for the culture producers because the high viscosity of the fermented growth medium makes it difficult to recover the cells by centrifugation or filtration. This study examined four approaches to reduce viscosity of the medium while producing high cell densities: incubation temperature, extended incubation in the stationary growth phase, production in alginate gel beads and fed-batch fermentation technology. Automated spectrophotometry (AS) was used to study the effects of temperature, pH and lactate level on growth of the strain. In AS assays, there was no significant difference in final maximal biomass production at temperatures ranging between 34ºC to 44ºC, but lower yields were noted at 46ºC. A pH below 6.0 and a lactate concentration higher than 4% almost completely prevented growth. Under batch fermentation conditions, the viscosity of the medium obtained at 37ºC was two fold higher than for 44ºC. For cultures produced at 37ºC, centrifugation at 10000 g during 5 min did not allow complete recovery of cells, in contrast to cultures grown at 44ºC. An extended period of incubation (5 hrs) in the stationary growth phase did not reduce the final viscosity of the growth medium. For similar biomass levels, the glucose-based fed-batch fermentation allowed a 40% reduction in viscosity of the fermented medium in comparison to traditional batch cultures. High-density cell populations (3 x 1010 CFU/g) were obtained when L. rhamnosus RW-9595M was grown in alginate beads. However, overall biomass yields in the immobilized cell bioreactor were half of those obtained in free-cell fermentations. Therefore three methods of producing concentrated EPS-producing cultures are proposed.




Full Text: | Full Text | Reprint PDF |

ISSN:  0717-3458

Contact: edbiotec@pucv.cl

Pontificia Universidad Católica de Valparaíso
Av. Brasil 2950, Valparaíso, Chile
Copyright © 1997- 2023 by Electronic Journal of Biotechnology