 Autotrophic Epsilonproteobacteria use the reverse Krebs cycle to fix carbon dioxide into biomass, a pathway originally thought to be of little environmental significance.The oxygen sensitivity of this pathway is consistent with their microaerophilic or anaerobic niche in these environments, and their likely evolution in the Mesoproterozoic oceans, which are thought to have been sulfidic with low levels of oxygen available from cyanobacterial photosynthesis.The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)  and National Center for Biotechnology Information (NCBI)
and the phylogeny is based on 16S rRNA-based LTP release 106 by 'The All-Species Living Tree' Project 

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