Importance of catalase in adaptive response and resistance to hydrogen peroxide in Haloferax IRU1

Haloferax IRU1 is an extremely halophilic Archaeon, which is highly resistant to the lethal effects of hydrogen peroxide. To investigate the role of catalase in the tolerance of Haloferax IRU1 to hydrogen peroxide stress, theexpression and activity of catalase by this archaeon was studied. When cells were treated with several levels of hydrogen peroxide, activity and expression of catalase increased, in comparison to that of untreated cells. This suggests that catalase is an important factor in the tolerance of Haloferax IRU1 to hydrogen peroxide stress.To investigate the adaptive response to the lethal effects of hydrogen peroxide in Haloferax IRU1, cultures when pretreated with sub-lethal levels of hydrogen peroxide, became more resistant to its lethal effects and exhibited higher levels of catalase than those of un-pretreated cultures. This indicates that catalase is induced during the adaptive response of this strain to hydrogen peroxide stress.