Nitrospira defluvii Spieck et al. 2006 Spieck E. Hartwig C. McCormack I. Maixner F. Wagner M. Lipski A. Daims H. Selective enrichment and molecular characterization of a previously uncultured Nitrospira-like bacterium from activated sludge. 2006 8 3 405 415 Environmental Microbiology Environ Microbiol 1462-2912 1462-2920 10.1111/j.1462-2920.2005.00905.x 16478447