 Nitrosomonadales comprises the families "Nitrosomonadaceae" (type family), "Methylophilacae", "Thiobacillaceae", "Sterolibacteriacae", "Spirillaceae" and "Gallionellaceae".The order comprises morphologies including rods, spirillae and curved rods.Most organisms are chemolithoautotrophs with some methylotrophs and heterotrophs 
Rhodocyclales comprises the families "Rhodocyclaceae" (type family), "Azonexaceae" and "Zoogloeaceae".