Bacillus
acidovorans - alcalophilus - aminovorans - amyloliquefaciens - atrophaeus - azotoformans - badius - benzoevorans - carboniphilus - cereus - chitinolyticus - circulans - cirroflagellosus - clausii - coagulans - cohnii - ehimensis - endophyticus - epiphytus - fastidiosus - filicolonicus - firmus - flexus - freudenreichii - fumarioli - gibsonii - haloalkaliphilus - halodurans - horti - insolitus - jeotgali - laevolacticus - lentus - licheniformis - lubinskii - macroides - marismortui - maroccanus - medusa - megaterium - methanolicus - mojavensis - mycoides - niacini - pacificus - pseudofirmus - pseudogordonae - pseudomycoides - psychrodurans - psychrosaccharolyticus - psychrotolerans - pumilus - racemilacticus - schlegelii - silvestris - siralis - smithii - sp. - sphaericus - sporothermadurans - subtilis - thermocloaceae - thuringiensis - vallismortis - vedderi - viscosus

Bacteriovorax
starrii

Bdellovibrio
bacteriovorus

Beijerinckia
acida - congensis - derxii - fluminensis - indica - mobilis

Beneckea
hyperoptica

Bergeyella
zoohelcum

Beutenbergia
cavernae

Bifidobacterium
adolescentis - angulatum - animalis - bifidum - breve - catenulatum - dentium - infantis - longum - pseudocatenulatum - pseudolongum - pullorum - thermophilum

Blastobacter
aggregatus - capsulatus - denitrificans

Blastochloris
viridis

Blastococcus
aggregatus

Bordetella
bronchiseptica

Brachybacterium
alimentarium - conglomeratum - faecium - paraconglomeratum - rhamnosum - tyrofermentans

Brackiella
oedipodis

Bradyrhizobium
japonicum

Brevibacillus
agri - borstelensis - brevis - choshinensis - formosus - invocatus - laterosporus - parabrevis - reuszeri

Brevibacterium
avium - casei - epidermidis - iodinum - linens - liquefaciens - otitidis - sp. - stationis

Brevundimonas
bacteroides - diminuta - vesicularis

Brochothrix
campestris - thermosphacta

Budvicia
aquatica

Burkholderia
ambiferia - cepacia - cocovenenans - graminis - phenacinium - pyrrocinia - vandii - vietnamiensis