prokaryotes - bacteria see Domain Bacteria Woese et al. 1990 Domain "Bacteria" Woese et al. 1990 Phylum "Proteobacteria" Garrity et al. 2005 see Superphylum Proteobacteria Craig et al. 2010 Class Alphaproteobacteria Garrity et al. 2006 Order Rhizobiales Kuykendall 2006 Family Beijerinckiaceae Garrity et al. 2006 Genus Methylovirgula Vorob'ev et al. 2009