ɔːlðˈoʊ ɪt wʌz lˈɔŋ bᵻlˈiːvd ðæt ðiːz ˈɔːɹɡənˌɪzəmz ɹᵻkwˈaɪɚɹ ˈɑːksɪdʒən tə mˌeɪk ðiːz kənvˈɜːʒənz, ɹˈiːsənt lˈɪɾɚɹᵻtʃɚ sədʒˈɛsts ðæt ˌænɛɹˈoʊbɪk ˌɑːksɪdˈeɪʃən ˈɔːlsoʊ ɛɡzˈɪsts fɔːɹ ðiːz sˈɪstəmz.
Although it was long believed that these organisms require oxygen to make these conversions, recent literature suggests that anaerobic oxidation also exists for these systems.