Hydrogenosomes and Mitosomes: Mitochondria of Anaerobic Eukaryotes

Volume 9 of the series Microbiology Monographs pp 1-20


Anaerobic Eukaryotes in Pursuit of Phylogenetic Normality: the Evolution of Hydrogenosomes and Mitosomes

  • William MartinAffiliated withInstitute of Botany, University of Düsseldorf Email author 

* Final gross prices may vary according to local VAT.

Get Access


The evolutionary relationship of hydrogenosomes and mitosomes to mitochondria is no longer an issue of contention for specialists who work on the organelles. Hydrogenosomes and mitosomes are mitochondria in the evolutionary sense in that they descend from one and the same eubacterial endosymbiont, but the evolutionary significance of eukaryotic anaerobes that possess hydrogenosomes, mitosomes, and anaerobically functioning mitochondria is an issue of some contention. This chapter serves to further develop the thesis that the role of oxygen in eukaryote evolution needs to be reconsidered and viewed in light of what geologists have discovered relatively recently regarding oxygen in Earth history. According to newer findings from geochemical studies, there existed during a protracted period of Earth ocean history, during which the oceans were mostly anoxic and sulfidic (“Canfield” oceans). This period started about 2.3 billion years ago and only came to an end about 580 million years ago. This was the time during which eukaryotes arose and diversified into their major lineages. In light of this, anaerobic eukaryotes with mitochondria are not, in an evolutionary sense, strange, obscure, unexpected, or otherwise out of the ordinary, hence no special or unusual mechanisms are required to explain their origin. They are normal in every respect, and so are their mitochondria.