SYMBIOTIC ASSOCIATION OF PSALTERIOMONAS-VULGARIS N SPEC WITH METHANOBACTERIUM-FORMICICUM

The free-living anaerobic flagellate Psalteriomonas vulgaris n. spec. is described. The organism has four flagella of equal length which arise immediately subapically to the anterior part of the cell, within the apex of the ventral groove. The ultrastructural organization of the mastigont system and the ventral groove show the characteristics of the genus Psalteriomonas. The cells harboured methanogenic endosymbionts which were associated with hydrogenosome-like organelles in which hydrogenase could be localized. The methanogenic bacteria were isolated and identified as Methanobacterium formicicum. After addition of 5% O2 to the cultures, the cells lost the methanogenic endosymbionts. P. vulgaris lacked cytochrome oxidase and catalase but contained superoxide dismutase.