Nitrospina gracilis Watson and Waterbury 1971 (Approved Lists 1980) Teske A. Alm E. Regan J.M. Toze S. Rittmann B.E. Stahl D.A. Evolutionary relationships among ammonia- and nitrite-oxidizing bacteria 1994 176 6623 6630 Journal of Bacteriology J Bacteriol 0021-9193 1098-5530 7961414