Characterization of superoxide dismutase in Streptococcus thermophilus

Streptococcus thermophilus AO54 possesses a single manganese-containing superoxide dismutase (MnSOD). The enzyme was found to be insensitive to cyanide or to a modified H2O2 treatment. The enzyme is expressed in a growth-phase-dependent fashion, increasing three- to fourfold upon entry into stationary phase. The specific activity for MnSOD was the same under anaerobic or aerobic conditions and was not induced by the presence of paraquat under aerobic conditions.