English: Hypothetical metabolic pathways and reversed electron transport in the anammoxosome. (a) Anammox catabolism that uses nitrite as the electron acceptor for the creation of a proton motive force over the anammoxosomal membrane. (b) Proton motive force- driven reversed electron transport combines central catabolism with nitrate reductase (NAR) to generate ferredoxin for carbon dioxide reduction in the acetyl-CoA pathway. HAO, hydrazine oxidoreductase; HD, hydrazine dehydrogenase; HH, hydrazine hydrolase; NIR, nitrite oxidoreductase; Q, quinine. Light blue diamonds, cytochromes; blue arrows, reductions; pink arrows, oxidations.