Transient Accumulation of Glycine Betaine and Dynamics of Endogenous Osmolytes in Salt-Stressed Cultures of Sinorhizobium meliloti - Université de Rennes Accéder directement au contenu
Article Dans Une Revue Applied and Environmental Microbiology Année : 1997

Transient Accumulation of Glycine Betaine and Dynamics of Endogenous Osmolytes in Salt-Stressed Cultures of Sinorhizobium meliloti

Roland Talibart
  • Fonction : Auteur
Mohamed Jebbar
Kamila Gouffi
  • Fonction : Auteur
Vianney Pichereau
Gwenola Gouesbet
Carlos Blanco
  • Fonction : Auteur
  • PersonId : 1122537
Théophile Bernard
  • Fonction : Auteur
  • PersonId : 857728
Jean-Alain Pocard
  • Fonction : Auteur

Résumé

The fate of exogenously supplied glycine betaine and the dynamics of endogenous osmolytes were investigated throughout the growth cycle of salt-stressed cultures of strains of Sinorhizobium meliloti which differ in their ability to use glycine betaine as a growth substrate, but not as an osmoprotectant. We present (sup13)C nuclear magnetic resonance spectral and radiotracer evidence which demonstrates that glycine betaine is only transiently accumulated as a cytoplasmic osmolyte in young cultures of wild-type strains 102F34 and RCR2011. Specifically, these strains accumulate glycine betaine as a preferred osmolyte which virtually prevents the accumulation of endogenous osmolytes during the lag and early exponential phases of growth. Then, betaine levels in stressed cells decrease abruptly during the second half of the exponential phase. At this stage, the levels of glutamate and the dipeptide N-acetylglutaminylglutamine amide increase sharply so that the two endogenous solutes supplant glycine betaine in the ageing culture, in which it becomes a minor osmolyte because it is progressively catabolized. Ultimately, glycine betaine disappears when stressed cells reach the stationary phase. At this stage, wild-type strains of S. meliloti also accumulate the disaccharide trehalose as a third major endogenous osmolyte. By contrast, glycine betaine is always the dominant osmolyte and strongly suppresses the buildup of endogenous osmolytes at all stages of the growth cycle of a mutant strain, S. meliloti GMI766, which does not catabolize this exogenous osmoprotectant under any growth conditions.

Dates et versions

hal-03374005 , version 1 (11-10-2021)

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Citer

Roland Talibart, Mohamed Jebbar, Kamila Gouffi, Vianney Pichereau, Gwenola Gouesbet, et al.. Transient Accumulation of Glycine Betaine and Dynamics of Endogenous Osmolytes in Salt-Stressed Cultures of Sinorhizobium meliloti. Applied and Environmental Microbiology, 1997, 63 (12), pp.4657-4663. ⟨10.1128/aem.63.12.4657-4663.1997⟩. ⟨hal-03374005⟩

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