Cadmium tolerance plasticity in Rhizobium leguminosarum bv. viciae: glutathione as a detoxifying agent

Etelvina Maria De Almeida Paula Figueira*, Ana Isabel Gusmão Lima, Sofia Isabel Almeida Pereira

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

65 Citations (Scopus)

Abstract

Rhizobium leguminosarum bv. viciae strains expressing different degrees of tolerance to metal stress were used in this work to study the basic mechanisms underlying heavy metal tolerance. We used various parameters to evaluate this response. The strains' growth responses under different Cd2+ concentrations were determined and we reported variation in Cd2+ tolerance. Total soluble protein content decreased drastically, revealing the toxic effects that intracellular Cd2+ imposes on cellular metabolism, but this decrease in protein content was particularly evident in sensitive and moderately tolerant strains. Tolerant strains presented the highest intracellular and wall-bound Cd2+ concentrations. Cd2+ induced increases in the expression of some specific proteins, which were identical in all tolerant strains. Glutathione levels remained unaltered in the sensitive strain and increased significantly in tolerant and moderately tolerant strains, suggesting the importance of glutathione in coping with metal stress. This work suggests that efflux mechanisms may not be the only system responsible for dealing with heavy metal tolerance. A clear correlation between glutathione levels and Cd2+ tolerance is reported, thus adding a novel aspect in bacteria protection against heavy metal deleterious effects.

Original languageEnglish
Pages (from-to)7-14
Number of pages8
JournalCanadian Journal of Microbiology
Volume51
Issue number1
DOIs
Publication statusPublished - Jan 2005
Externally publishedYes

Keywords

  • Glutathione
  • Heavy metal
  • Protein expression
  • Rhizobia
  • Thiol quantification

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