organelle of some anaerobic ciliates , trichomonads and fungi . The hydrogenosomes of trichomonads (the most studied of the hydrogenosome-containing microorganisms) produce molecular hydrogen , acetate , carbon dioxide and ATP by the combined actions of pyruvate:ferredoxin oxido-reductase , hydrogenase , acetate:succinate CoA transferase and succinate thiokinase . Superoxide dismutase ,