Advanced

Altered nucleotide sugar metabolism in Streptococcus thermophilus interferes with nitrogen metabolism

Svensson, Malin LU ; Lohmeier-Vogel, Elke LU ; Waak, E.; Svensson, U. and Rådström, Peter LU (2007) In International Journal of Food Microbiology 113(2). p.195-200
Abstract
Exopolysaccharide (EPS)-producing Streptococcus thermophilus strains have attracted interest recently, since the EPSs act as natural viscosifiers and texture enhancers of fermented foods. We have previously reported that the low level of EPS production by S. thermophilus LY03 could be improved by altering the activities of enzymes in the central carbon metabolism involved in the nucleotide sugar metabolism. In this study, we observed a reduced growth in milk for the strains with increased UDP-glucose pyrophosphorylase (GalU) activity together with either enhanced phosphoglucomutase activity, and/or enhanced activity of the Leloir enzymes. Rapid growth of these mutants in milk could be restored by the addition of four specific amino acids,... (More)
Exopolysaccharide (EPS)-producing Streptococcus thermophilus strains have attracted interest recently, since the EPSs act as natural viscosifiers and texture enhancers of fermented foods. We have previously reported that the low level of EPS production by S. thermophilus LY03 could be improved by altering the activities of enzymes in the central carbon metabolism involved in the nucleotide sugar metabolism. In this study, we observed a reduced growth in milk for the strains with increased UDP-glucose pyrophosphorylase (GalU) activity together with either enhanced phosphoglucomutase activity, and/or enhanced activity of the Leloir enzymes. Rapid growth of these mutants in milk could be restored by the addition of four specific amino acids, i.e. Glu, His, Met, and Val. This amino acid requirement was confirmed in a defined medium. Furthermore, the P-31 NMR spectra showed higher levels of the GalU reactants pyrophosphate (PPi) and UDP-glucose in the engineered strain, TMB 6013, compared to the parent strain, LY03. These products plus Glu and the GalU reactant UTP are known to be involved in the nitrogen regulatory system in many bacteria. Thus, these results suggest that the reaction catalyzed by GalU is connected to the nitrogen demand of these engineered strains. (c) 2006 Elsevier B.V. All rights reserved. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
fermented milk, UDP-glucose, Streptococcus thermophilus, pyrophosphorylase
in
International Journal of Food Microbiology
volume
113
issue
2
pages
195 - 200
publisher
Elsevier
external identifiers
  • wos:000243774100011
  • scopus:33845875706
ISSN
0168-1605
DOI
10.1016/j.ijfoodmicro.2006.06.032
language
English
LU publication?
yes
id
3be2e7ac-6c9f-4bb9-bf55-502a2d878285 (old id 676219)
date added to LUP
2007-12-18 16:05:53
date last changed
2017-10-29 03:40:50
@article{3be2e7ac-6c9f-4bb9-bf55-502a2d878285,
  abstract     = {Exopolysaccharide (EPS)-producing Streptococcus thermophilus strains have attracted interest recently, since the EPSs act as natural viscosifiers and texture enhancers of fermented foods. We have previously reported that the low level of EPS production by S. thermophilus LY03 could be improved by altering the activities of enzymes in the central carbon metabolism involved in the nucleotide sugar metabolism. In this study, we observed a reduced growth in milk for the strains with increased UDP-glucose pyrophosphorylase (GalU) activity together with either enhanced phosphoglucomutase activity, and/or enhanced activity of the Leloir enzymes. Rapid growth of these mutants in milk could be restored by the addition of four specific amino acids, i.e. Glu, His, Met, and Val. This amino acid requirement was confirmed in a defined medium. Furthermore, the P-31 NMR spectra showed higher levels of the GalU reactants pyrophosphate (PPi) and UDP-glucose in the engineered strain, TMB 6013, compared to the parent strain, LY03. These products plus Glu and the GalU reactant UTP are known to be involved in the nitrogen regulatory system in many bacteria. Thus, these results suggest that the reaction catalyzed by GalU is connected to the nitrogen demand of these engineered strains. (c) 2006 Elsevier B.V. All rights reserved.},
  author       = {Svensson, Malin and Lohmeier-Vogel, Elke and Waak, E. and Svensson, U. and Rådström, Peter},
  issn         = {0168-1605},
  keyword      = {fermented milk,UDP-glucose,Streptococcus thermophilus,pyrophosphorylase},
  language     = {eng},
  number       = {2},
  pages        = {195--200},
  publisher    = {Elsevier},
  series       = {International Journal of Food Microbiology},
  title        = {Altered nucleotide sugar metabolism in Streptococcus thermophilus interferes with nitrogen metabolism},
  url          = {http://dx.doi.org/10.1016/j.ijfoodmicro.2006.06.032},
  volume       = {113},
  year         = {2007},
}