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Piromyces sp. E2
The Indian Elephant (Elephas maximus) is one of the many hosts of Piromyces sp. Photo from Jayanand Govindaraj via Wikipedia.

Members of the phylum Chytridiomycota are unique among the fungi in possessing flagellated zoospores. Furthermore, the anaerobic chytrid fungi represent a unique order (Neocallismasticales) within the chytrids that possess hydrogenosomes (hydrogen- and ATP-producing organelles), lack mitochondria, and grow as commensal organisms in the gut of a variety of herbivores. These obligate anaerobic chytrid symbionts play a key role in the digestion of plant cell wall material and provision of hydrogen to the herbivore digestive tract ecosystem. They have been found in virtually all herbivorous mammals studied so far, including elephants, llamas, donkeys, horses, capybaras, and ruminants. Physiologically, they are particularly interesting because they perform a bacterial-type mixed-acids fermentation. Genes from anaerobic chytrids have been used in biotechnology applications, such as expression in the yeast Saccharomyces cerevisiae for ethanol production. Sequencing the genome of Piromyces sp. E2 will generate scientifically valuable data for studying the evolution of unicellular eukaryotes in general, and more specifically the anaerobic fungi within the phylum Chytridiomycota; for hydrogenosome biochemistry and evolutionary origins; for microbial ecology and symbiosis; and for the evolution and physiology of cell motility (flagella).

Piromyces is of particular interest for an analysis of the evolution of hydrogenosomes and for its adaptation to anaerobic environments. It may be shown that the hydrogenosomes of Piromyces evolved from fungal mitochondria. A biological feature documented so far only in this organism is the retargeting of functional "mitochondrial" enzymes to the cytoplasm. Knowledge of the genome would allow a thorough analysis of this phenomenon, which will provide further insights into mitochondrial functions/dysfunctions and the evolution of the various, rather divergent types of aerobic and anaerobic mitochondria.

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