El glutatión juega un rol importante en el crecimiento de Bradyrhizobium sp en condiciones de estrés ambiental

BIANUCCI ELIANA, SOBREVALS LUCIANO, FABRA ADRIANA, CASTRO STELLA.

Villa Giardino, Córdoba

Congreso; XV Jornadas científicas de la Sociedad de Biología de Córdoba; 2005

Sociedad de Biología de Córodoba

The glutathione (GSH) plays an important role in the mechanism of defense of the microorganisms against different environmental stresses. The objective of the work was to investigate the role of GSH in Bradyrhizobium sp. SEMIA 6144 under different environmental stresses such as acid (pH 5.5), saline (0.3 M NaCl), oxidative (0.5 mM H2O2) and the toxic agent methylglyoxal (1.5 mM). For that, a GSH-deficient mutant (Bradyrhizobium sp 6144-DS7Z) was obtained by disruption of gshA gene, which encodes the enzyme g-glutamylcysteine synthetase. Growth of the mutant strain was significantly reduced in MSM medium and the GSH content was very low, about 4% of the wild-type level. The defect caused by disruption of the gshA gene in the growth of mutant strain cannot be reversed by the addition up to 100 µM GSH in MSM medium. However, the growth of the mutant strain in a rich medium (YEM) was greater suggesting that at least some of the functions of GSH could be provided by peptides and amino acids but not all. It is well known that GSH participates in the mechanism of regulation of the cytoplasmic pH increasing K+ level. Thus, the wild-type strain increased K+ level when cells were exposed to acid stress. In conclusion, the data presented in this study demonstrate that GSH plays an important role in the survival of Bradyrhizobium sp SEMIA 6144 under different stress conditions.