Abiotropha
balaenopterae

Abiotrophia
sp

Acetobacter
aceti - estunensis - lovaniensis - orleanensis - pasteurianus - pomorum - sp.

Acetobacterium
malicum

Achromobacter
cholinophagum - piechaudii - ruhlandii - xylosoxidans

Acidiphilium
acidophilum - cryptum - sp.

Acidithiobacillus
ferrooxidans - thiooxidans

Acidobacterium
capsulatum

Acidocella
aromatica

Acidovorax
delafieldii - facilis - sp.

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

Acrocarpospora
corrugata

Actinobacillus
delphinicola

Actinocorallia
herbida - libanotica

Actinokineospora
diospyrosa - globicatena - inagensis - riparia - terrae

Actinomadura
atramentaria - citrea - cremea - formosensis - hibisca - madurae - nitritigens - sp. - spadix - verrucosospora - viridis

Actinomyces
hyovaginalis - sp.

Actinoplanes
auranticolor - brasiliensis - campanulatus - consettensis - cyaneus - cylindrica - deccanensis - derwentensis - digitatis - durhamensis - ferrugineus - garbadinensis - globisporus - humidus - ianthinogenes - italicus - kinshanensis - kunmingensis - liguriae - lobatus - missouriensis - palleronii - pallidoaurantiacus - pekinensis - penicillatus - philippinensis - pilifera - purpeobrunneus - pyriformis - rectilineatus - regularis - roseosporangius - rutilosporangius - teichomyceticus - tuftoflagellus - utahensis - violaceochromogenes - violaceus - yunnanensis

Actinopolyspora
halophila - mortivallis

Actinosynnema
mirum

Aerococcus
urinae - urinae-equi - viridans

Aeromicrobium
erythreum - fastidiosum

Aeromonas
allosaccharophila - bestiarum - caviae - encheleia - enteropelogenes - eucrenophila - hydrophila - ichthiosmia - media - salmonicida - schubertii - sobria - sp. - veronii

Agrobacterium
agile - ferrugineum - luteum - sanguineum - sp.

Agrococcus
citreus - jenensis

Agromonas
oligotrophica

Agromyces
mediolanus - ramosus

Ahrensia
kielensis

Alcaligenes
faecalis - latus - sp.

Alcanivorax
borkumensis

Alicyclobacillus
acidocaldarius - acidoterrestris

Alkalibacterium
olivapovliticus

Allochromatium
vinosum

Alloiococcus
otitis

Alteromonas
macleodii - marinoglutinosa - sp.

Aminobacter
aminovorans

Aminomonas
aminovorus

Ammoniphilus
oxalaticus - oxalivorans

Amycolatopsis
coloradensis - eurytherma - mediterranei - methanolica - orientalis - sacchari

Anaerococcus
prevotii

Ancalomicrobium
adetum

Ancylobacter
aquaticus - sp.

Aneurinibacillus
aneurinolyticus - migulanus - thermoaerophilus

Aquabacterium
citratiphilum - commune - parvum

Aquaspirillum
anulus - arcticum - delicatum - giesbergeri - itersonii - metamorphum - peregrinum - polymorphum - putridiconchylium - serpens - sinuosum - sp.

Arcanobacterium
haemolyticum - pluranimalium - pyogenes

Arenibacter
latericius

Arhodomonas
aquaeolei

Arthrobacter
agilis - atrocyaneus - aurescens - chlorophenolicus - citreus - crystallopoietes - duodecadis - globiformis - histidinolovorans - mysorens - nicotianae - oxydans - paraffineus - pascens - polychromogenes - protophormiae - ramosus - sialophilus - sp. - stabilis - sulfureus - uratoxydans - ureafaciens - viscosus

Asaia
bogorensis

Asticcacaulis
excentricus

Atopobium
minutum - parvulum - rimae

Azoarcus
communis - indigens

Azomonas
agilis - insignis - macrocytogenes

Azorhizobium
caulinodans

Azorhizophilus
paspali

Azospirillum
amazonense - brasilense - halopraeferens - lipoferum

Azotobacter
beijerinckii - chroococcum - vinelandii