Anaerobic eukaryote evolution: hydrogenosomes as biochemically modified mitochondria?

Hydrogenosomes are energy generating organelles which are found in a variety of anaerobic microbial eukaryotes. Recent data suggest that some of these hydrogenosomes may be bichemically modified mithochondria, subverting the conventional role of this compartment from one of oxidative phosphorylation, to one of hydrogen evolving fermentation. The origins of the key enzymes which are responsible for hydrogen porduction are currently obscure but they are not considered to be typical of most eukaryotes.