Oxygen responses of the free-living anaerobic amoeboflagellate Psalteriomonas lanterna

Abstract The effects of O₂ on growth of the anaerobic amoeboflagellate Psalteriomonas lanterna were studied. The organism tolerates low oxygen tensions (about 1% O₂ atm. sat.) and under these conditions growth was stimulated in mixed populations. Catalase could not be found in the cells, whereas superoxide dismutase was present. Addition of O₂ resulted in loss of the methanogenic endosymbionts and favoured the transformation to amoeba cells. Symbiont-free cells did not grow under anaerobic conditions probably due to the accumulation of H₂.