'Nitrospira' is a genus of bacteria in the phylum Nitrospirae. The first member of this genus was described 1986 by Watson et al. isolated from the Gulf of Maine. The bacterium was named Nitrospira marina. The second member of this genus was discovered in 1995 from a corroded iron pipe in a Moscow heating system. The bacterium was named Nitrospira moscoviensis and is a gram-negative nitrite-oxidising organism with a helical to vibroid morphology 0.9-2.2 x 0.2-0.4 micrometres in size.