Higher proton motive force

[Samizv]

Hi, I was just wondering about this question on my first year biology course; Nitrosomonas uses ammonia to reduce an electron transport chain and then ammonia is reduced to nitrate, while Nitrobacters uses nitrate, which is reduced to nitrite...which would produce a higher proton motive force, and how would you predict it?
Thanks

[JackBean]

ammonia is oxidized to nitrate