Magnesium chemical rescue to cobalt-poisoned cells from Rhodobacter sphaeroides

Rhodobacter sphaeroides is able to tolerate high cobaltous ion concentrations, notwithstanding the detrimental effects on growth parameters and bacteriochlorophyll content (Giotta et al. 2006). In order to study the influence of magnesium concentration on cobalt toxicity, growth experiments were performed with variable magnesium and cobalt concentrations. At high cobalt concentration the increase of Mg2+ in the growth medium results in a significant increase in growth rate and population size reached at the stationary phase, contrasting cobalt toxic effect. Moreover cobalt-exposed bacteria showed a reduced Mg content with respect to control cells. These results demonstrate the existence of an interrelationship in the metabolism of magnesium and cobalt.