<Tr> <Td> sulfate respiration </Td> <Td> obligate anaerobes </Td> <Td> sulfate SO </Td> <Td> sulfide HS </Td> <Td> - 0.22 </Td> <Td> Many Deltaproteobacteria species in the orders Desulfobacterales, Desulfovibrionales, and Syntrophobacterales </Td> </Tr> <Tr> <Td> methanogenesis (carbonate reduction) </Td> <Td> methanogens </Td> <Td> carbon dioxide CO </Td> <Td> methane CH </Td> <Td> - 0.25 </Td> <Td> Methanosarcina barkeri </Td> </Tr> <Tr> <Td> sulfur respiration (sulfur reduction) </Td> <Td> facultative anaerobes and obligate anaerobes </Td> <Td> sulfur S </Td> <Td> sulfide HS </Td> <Td> - 0.27 </Td> <Td> Desulfuromonadales </Td> </Tr> <Tr> <Td> acetogenesis (carbonate reduction) </Td> <Td> obligate anaerobes </Td> <Td> carbon dioxide CO </Td> <Td> acetate </Td> <Td> - 0.30 </Td> <Td> Acetobacterium woodii </Td> </Tr>

Which state of cellular respiration is an anaerobic process