Abiotrophia
defectiva

Acetobacter
aceti - pasteurianus - pomorum

Acholeplasma
laidlawii

Achromobacter
piechaudii - ruhlandii - xylosoxidans

Acidaminococcus
fermentans

Acidiphilium
acidophilum

Acidithiobacillus
thiooxidans

Acidomonas
methanolica

Acidovorax
anthurii - avenae - delafieldii - facilis - konjaci - temperans

Acinetobacter
baumannii - calcoaceticus - genomospecies - haemolyticus - johnsonii - junii - lwoffii - radioresistens - sp.

Actinoalloteichus
cyanogriseus

Actinobacillus
capsulatus - delphinicola - equuli - hominis - indolicus - lignieresii - minor - muris - pleuropneumoniae - porcinus - rossii - salpingitidis - scotiae - seminis - sp. - succinogenes - suis - ureae

Actinobaculum
schaalii - suis

Actinocorallia
longicatena

Actinomadura
formosensis - luteofluorescens - macra - madurae - pelletieri - rubrobrunea - rugatobispora - spadix - umbrina - verrucosospora - vinacea - viridis - yumaensis

Actinomyces
bovis - bowdenii - catuli - denticolens - europaeus - funkei - georgiae - gerencseriae - graevenitzii - hordeovulneris - howellii - hyovaginalis - israelii - marimammalium - meyeri - naeslundii - neuii - odontolyticus - radicidentis - radingae - slackii - sp - sp. - turicensis - urogenitalis - viscosus

Aerococcus
christensenii - sanguicola - urinae - viridans

Aeromonas
allosaccharophila - bestiarum - caviae - encheleia - enteropelogenes - eucrenophila - hydrophila - ichthiosmia - jandaei - media - popoffii - salmonicida - schubertii - sobria - veronii

Afipia
birgiae - broomeae - clevelandensis - felis - genomospecies - massiliensis

Agrobacterium
sp.

Agrococcus
citreus - jenensis

Agromyces
cerinus - fucosus - hippuratus - mediolanus - ramosus

Ahrensia
kielensis

Alcaligenes
defragrans - faecalis - latus - sp. - tolerans

Alcanivorax
borkumensis

Algicola
bacteriolytica

Alicyclobacillus
acidocaldarius - acidoterrestris

Alishewanella
fetalis

Alistipes
putredinis

Alloiococcus
otitis

Alterococcus
agarolyticus

Alteromonas
fuliginea - macleodii

Alysiella
filiformis

Aminobacter
aminovorans

Ammoniphilus
oxalaticus - oxalivorans

Amycolatopsis
japonica - mediterranei - rubida - sacchari - thermoflava

Anaerococcus
lactolyticus - octavius - prevotii - tetradius - vaginalis

Anaeroglobus
geminatus

Aneurinibacillus
aneurinilyticus - migulanus - thermoaerophilus

Antarctobacter
heliothermus

Aquabacterium
citratiphilum - commune - parvum

Aquamicrobium
defluvii

Aquaspirillum
itersonii - polymorphum - serpens - sinuosum - sp.

Arcanobacterium
bernardiae - haemolyticum - phocae - pluranimalium - pyogenes

Arcobacter
butzleri - cryaerophilus - nitrofigilis - skirrowii

Arhodomonas
aquaeolei

Arthrobacter
agilis - albus - atrocyaneus - aurescens - citreus - creatinolyticus - crystallopoietes - cumminsii - duodecadis - globiformis - histidinolovorans - ilicis - luteolus - mysorens - nasiphocae - nicotianae - nicotinovorans - oxydans - pascens - polychromogenes - protophormiae - ramosus - sp. - sulfureus - uratoxydans - ureafaciens - viscosus - woluwensis

Asanoa
ferruginea

Asticcacaulis
biprosthecium - excentricus

Atopobacter
phocae

Atopobium
parvulum - vaginae

Avibacterium
avium - gallinarum - paragallinarum - volantium

Azomonas
macrocytogenes

Azospirillum
irakense - lipoferum

Azotobacter
beijerinckii - chroococcum - vinelandii