Abiotrophia Kawamura et al., 1995 (verified source for family)
Acaricomes Pukall et al., 2006 (verified source for family)
Acetanaerobacterium Chen & Dong, 2004 (verified source for family)
Acetimonas Orla-Jensen, 1909 accepted as Acetobacter Beijerinck, 1898 (Approved Lists, 1980) (verified source for family)
Acetitomaculum Greening & Leedle, 1995 (verified source for family)
Acetivibrio Patel, Khan, Agnew & Colvin, 1980 (verified source for family)
Acetoanaerobium Sleat et al., 1985 (name verified source)
Acetobacter Beijerinck, 1898 (Approved Lists, 1980) (name verified source)
Acetobacterium Balch, Schoberth, Tanner & Wolfe, 1977 (Approved Lists, 1980) (verified source for family)
Acetofilamentum Dietrich et al., 1989 (verified source for family)
Acetogenium Leigh & Wolfe, 1983 accepted as Thermoanaerobacter Wiegel & Ljungdahl, 1982 (additional source)
Acetogluconobacter Asai, 1935 accepted as Gluconobacter Asai, 1935 (Approved Lists, 1980) (verified source for family)
Acetohalobium Zhilina & Zavarzin, 1990 (verified source for family)
Acetomadura accepted as Microbispora Nonomura & Y. Ohara, 1957 (Approved Lists, 1980) (verified source for family)
Acetomicrobium Soutschek et al., 1985 (verified source for family)
Acetonema Kane & Breznak, 1992 (name verified source)
Acetothermus Dietrich et al., 1988 (verified source for family)
Acholeplasma Edward & Freundt, 1970 (Approved Lists, 1980) (verified source for family)
Achromatium Schewiakoff, 1893 (Approved Lists, 1980) (verified source for family)
Achromobacter Yabuuchi & Yano, 1981 (verified source for family)
Acidaminobacter Stams & Hansen, 1985 (name verified source)
Acidaminococcus Rogosa, 1969 (Approved Lists, 1980) emend. Jumas-Bilak et al., 2007 (name verified source)
Acidianus Segerer et al., 1986 (verified source for family)
Acidicaldus Johnson et al., 2006 (verified source for family)
Acidimicrobium Clark & Norris, 1996 (verified source for family)
Acidiphilium Harrison, 1981 (verified source for family)
Acidisphaera Hiraishi, Matsuzawa, Kanbe & Wakao, 2000 (verified source for family)
Acidithiobacillus Kelly & Wood, 2000 (verified source for family)
Acidobacterium Kishimoto et al., 1991 (verified source for family)
Acidocella Kishimoto et al., 1996 (verified source for family)
Acidomonas Urakami, Tamaoka, Suzuki & Komagata, 1989 (verified source for family)
Acidothermus Mohagheghi, Grohmann, Himmel, Leighton & Updegraff, 1986 (verified source for family)
Acidovorax Willems, Falsen, Pot, Jantzen, Hoste, Vandamme, Gillis, Kersters & De Ley, 1990 (verified source for family)
Acinetobacter Brisou & Prévot, 1954 (Approved Lists, 1980) (verified source for family)
Acinomyces accepted as Fusobacterium Knorr, 1922 (Approved Lists, 1980) (verified source for family)
Acinothrix Novácek, 1938 accepted as Planctomyces M. Gimesi, 1924 (Approved Lists, 1980) (source of synonymy)
Acrocarpospora Tamura et al., 2000 (verified source for family)
Actibacter Kim, Kim, Hahm, Kim, Chun & Cha, 2008 (verified source for family)
Actinoalloteichus Tamura et al., 2000 (verified source for family)
Actinobacillus Brumpt, 1910 (Approved Lists, 1980) (verified source for family)
Actinobaculum Lawson, Falsen, Akervall, Vandamme & Collins, 1997 (verified source for family)
Actinobifida Krasil'nikov & Agre, 1964 accepted as Thermoactinomyces Tsilinsky, 1899 (Approved Lists, 1980) (source of synonymy)
Actinobispora Jiang et al., 1991 (verified source for family)
Actinocatenispora Thawai et al., 2006 (verified source for family)
Actinocorallia Iinuma et al., 1994 (verified source for family)
Actinokineospora Hasegawa, 1988 (additional source)
Actinomadura H. Lechevalier & M.P. Lechevalier, 1968 (Approved Lists, 1980) (basis of record)
Actinomyces Harz, 1877 (Approved Lists, 1980) (basis of record)
Actinomycetospora Jiang et al., 2008 (verified source for family)
Actinoplanes Couch, 1950 (Approved Lists, 1980) (basis of record)
Actinopolymorpha Wang, Zhang, Xu, Ruan & Wang, 2001 (verified source for family)
Actinopolyspora Gochnauer, K.G. Johnson & Kushner, 1975 (Approved Lists, 1980) (basis of record)
Actinopycnidium Krasil'nikov, 1962 (Approved Lists, 1980) (verified source for family)
Actinospica Cavaletti, Monciardini, Schumann, Rohde, Bamonte, Busti, Sosio, Donadio, 2006 (verified source for family)
Actinospicaceae Cavaletti, Monciardini, Schumann, Rohde, Bamonte, Busti, Sosio, Donadio, 2006 emend. Zhi, Li & Stackebrandt, 2009 (extant flag source)
Actinospicaceae Cavaletti, Monciardini, Schumann, Rohde, Bamonte, Busti, Sosio, Donadio, 2006 emend. Zhi, Li & Stackebrandt, 2009 (basis of record)
Actinosporangium Krasil'nikov & Yuan, 1961 (Approved Lists, 1980) (verified source for family)
Actinosynnema T. Hasegawa, H. Lechevalier & M.P. Lechevalier, 1978 (Approved Lists, 1980) (basis of record)
Actinotalea Yi, Schumann & Chun, 2007 (verified source for family)
Adhaeribacter Rickard, Stead, O'May, Lindsay, Banner, Handley & Gilbert (basis of record)
Adlercreutzia Maruo et al., 2008 (basis of record)
Advenella Coenye et al., 2005 (verified source for family)
Aegyptianella Carpano, 1929 (Approved Lists, 1980) (verified source for family)
Aequorivita Bowman & Nichols, 2002 (verified source for family)
Aeriscardovia Simpson et al., 2004 (verified source for family)
Aerococcus Williams et al., 1953 (Approved Lists, 1980) (verified source for family)
Aeromicrobium Miller et al., 1991 (verified source for family)
Aeromonas Stanier, 1943 (Approved Lists, 1980) (verified source for family)
Aeropyrum Sako, Nomura, Uchida, Ishida, Morii, Koga, Hoaki & Maruyama, 1996 (verified source for family)
Aestuariibacter Yi et al., 2004 (verified source for family)
Aestuariimicrobium Jung, Kim, Song, Lee, Oh & Yoon, 2007 (verified source for family)
Afipia Brenner, Hollis, Moss, English, Hall, Vincent, Radosevic, Birkness, Bibb, Quinn, Swaminathan, Weaver, Reeves, O'Connor, Hayes, Tenover, Steigerwalt, Perkins, Daneshvar, Hill, Washington, Woods, Hunter, Hadfield, Ajello, Kaufmann, Wear & Wenger, 1992 (verified source for family)
Agarivorans Kurahashi & Yokota, 2004 (verified source for family)
Aggregatibacter Nørskov-Lauritsen & Kilian, 2006 (verified source for family)
Agitococcus Franzmann & Skerman, 1981 (verified source for family)
Agreia Evtushenko et al., 2001 (verified source for family)
Agrobacterium Conn, 1942 (Approved Lists, 1980) (verified source for family)
Agrococcus Groth, Schumann, Weiss, Martin & Rainey, 1996 (verified source for family)
Agromonas Ohta & Hattori, 1985 (verified source for family)
Agromyces Gledhill & Casida, 1969 (Approved Lists, 1980) emend. Zgurskaya, Evtushenko, Akimov, Voyevoda, Dobrovolskaya, Lysak & Kalakoutskii, 1992 (verified source for family)
Ahrensia Uchino et al., 1999 (verified source for family)
Akkermansiaceae Hedlund & Derrien, 2012 (basis of record)
Akkermansiaceae Hedlund & Derrien, 2012 (extant flag source)
Albibacter Doronina et al., 2001 (verified source for family)
Albidovulum Albuquerque, Santos, Travassos, Nobre, Rainey, Wait, Empadinhas, Silva & da Costa, 2003 (verified source for family)
Albimonas Lim, Jeon, Jang, Park, Shin, Yeo & Kim, 2008 (verified source for family)
Alcaligenes Castellani & Chalmers, 1919 (Approved Lists, 1980) (verified source for family)
Alcanivoracaceae corrig. Golyshin et al., 2005 (extant flag source)
Alcanivoracaceae corrig. Golyshin et al., 2005 (basis of record)
Alcanivorax Yakimov et al., 1998 (verified source for family)
Algibacter Nedashkovskaya, Kim, Han, Rhee, Lysenko, Rohde, Zhukova, Frolova, Mikhailov & Bae, 2004 (verified source for family)
Algicola Ivanova et al., 2004 (verified source for family)
Algoriphagus Bowman, Mancuso Nichols & Gibson, 2003 (verified source for family)
Alicycliphilus Mechichi, Stackebrandt & Fuchs (verified source for family)
Alicyclobacillus Wisotzkey, Jurtshuk, Fox, Deinhard & Poralla, 1992 (verified source for family)
Aliivibrio Urbanczyk, Ast, Higgins, Carson & Dunlap, 2007 (verified source for family)
Alishewanella Fonnesbech Vogel, Venkateswaran, Christensen, Falsen, Christiansen & Gram, 2000 (verified source for family)
Alistipes Rautio, Eerola, Vaisanen-Tunkelrott, Molitoris, Lawson, Collins & Jousimies-Somer, 2003 (verified source for family)
Alkalibacillus Jeon et al., 2005 (verified source for family)
Alkalibacter Garnova, Zhilina, Tourova, Kostrikina & Zavarzin, 2005 (verified source for family)

 Taxonomic remark

 for Candidatus Nostocoida van Veen, 1973

Unaccepted name (status = Candidatus), now = Tetrasphaera (several species), refer Euzéby. [details]