INSIBIO   05451
INSTITUTO SUPERIOR DE INVESTIGACIONES BIOLOGICAS
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Protection against oxidative stress depends on phosphate concentration in Escherichia coli stationary phase
Autor/es:
SCHURIG-BRICCIO LA; RODRÍGUEZ-MONTELONGO L; RINTOUL MR; RAPISARDA VA
Lugar:
Santiago de Chile (Chile)
Reunión:
Congreso; VI Meeting of the Society for Free Radical Biology and Medicine, South American Group (Free Radicals and Antioxidants in Chile); 2009
Institución organizadora:
Society for Free Radical Biology and Medicine
Resumen:
E. coli gradually decline the capacity to resist oxidative stress during stationary phase. However, we have previously reported that, E. coli cells grown in media containing at least 37 mM phosphate, maintained in stationary phase ndh expression, high viability and low NADH/NAD+ ratio. Here, the effect of different phosphate concentrations in the growth media was evaluated. We assayed several respiratory and defense genes expression, reactive oxygen species (ROS) production, damage to lipids and proteins, and the tolerance to H2O2 and copper in stationary E. coli cells. Media with different phosphate concentrations: LPM, limited phosphate medium (0.1 mM); SPM, sufficient phosphate medium (2 mM); and HPM, high phosphate medium (37 mM) were used. Interestingly, cells grown in LPM and HPM maintained a higher viability than cells grown in SPM until 96 h of culture. Nevertheless, the expression of several aerobic respiratory genes (ndh, nuoAB, sdhC, cydA and ubiC) and defense genes (katG and ahpC) were maintained until 96 h of culture only in HPM. Additionally, in this medium, ROS production was minimal and consequently the levels of thiobarbituric acid-reactive substances (TBARS) and protein carbonylation were lower than the expected for stationary cells. The ROS and TBARS production were high and similar in LPM and in SPM. It is important to note that a high expression of defense genes (katG and ahpC) was observed in LPM stationary cells. Together, our results indicate that cells grown in HPM exhibit advantages to resist endogenous and exogenous (H2O2 or copper) oxidative stress in stationary phase.