Enhanced superoxide production by membrane vesicles from Halobacterium halobium in a hyposaline environment

Membrane vesicles were prepared from the halophilic archaebacterium, Halobacterium halobium, which was grown either in medium containing 4 M NaCl or in a relatively hyposaline medium containing 1.25 M NaCl. Membrane vesicles prepared from bacteria grown in the lower salt environment consumed more oxygen, oxidized more NADH and generated more superoxide than vesicles prepared from cells grown in the normal 4 M NaCl containing medium. The enhanced respiratory activity of the membrane fragments obtained from the halophile which was grown and assayed in a hyposaline environment, along with the concomitant increased flux in superoxide, demonstrate a relation between an environmental perturbation and an altered electron transport activity.