| bifidobacteriaceae bacterium sp2-iso-ab41 | -3 | species | bacteria | bacteria | 865753 |
| beutenbergia | 4 | genus | bacteria | | 84756 |
| bermanella | 1 | genus | bacteria | | 599651 |
| bergeriella | 2 | genus | bacteria | | 334108 |
| belnapia | 1 | genus | bacteria | | 365532 |
| bellilinea | 2 | genus | bacteria | | 475960 |
| belliella | 24 | genus | bacteria | | 232244 |
| beijerinckia | 22 | genus | bacteria | | 532 |
| beggiatoa | 50 | genus | bacteria | | 1021 |
| bdellovibrio | 33 | genus | bacteria | | 958 |
| baylisascaris melis | -3 | species | | helminths | |
| baylisascaris laevis | -3 | species | | helminths | |
| baylisascaris columnaris | 1 | species | invertebrates | helminths | 575210 |
| baylisascaris | 22 | genus | invertebrates | | 6258 |
| barnesiella | 5 | genus | bacteria | | 397864 |
| balneola | 1 | genus | bacteria | | 455358 |
| balneimonas | 2 | genus | bacteria | | 266832 |
| balnearium | 3 | genus | bacteria | | 223787 |
| bacteroides xylanisolvens | 2 | species | bacteria | bacteria | 371601 |
| bacteroides rodentium | 1 | species | bacteria | bacteria | 691816 |
| bacteriovorax | 8 | genus | bacteria | | 146784 |
| bacillus thioparans | 1 | species | bacteria | bacteria | 370439 |
| bacillus fordii | 2 | species | bacteria | bacteria | 254759 |
| bacillus flexus | 5 | species | bacteria | bacteria | 86664 |
| bacillus endophyticus | 2 | species | bacteria | bacteria | 135735 |
| bacillus aquimaris | 4 | species | bacteria | bacteria | 189382 |
| babesia taylori | -3 | species | | protozoa | |
| babesia odocoilei | 14 | species | invertebrates | protozoa | 36766 |
| azovibrio | 3 | genus | bacteria | | 146935 |
| azospirillum | 80 | genus | bacteria | | 191 |
| azospira | 17 | genus | bacteria | | 146937 |
| azorhizophilus | 1 | genus | bacteria | | 157913 |
| azorhizobium | 54 | genus | bacteria | | 6 |
| azonexus | 3 | genus | bacteria | | 146936 |
| azomonas | 13 | genus | bacteria | | 69961 |
| azohydromonas | 2 | genus | bacteria | | 312063 |
| azoarcus | 48 | genus | bacteria | | 12960 |
| averyella | 1 | genus | bacteria | | 347014 |
| auxarthron umbrinum | 5 | species | plants | fungi | 203537 |
| aureispira | 2 | genus | bacteria | | 365032 |
| aureimonas | -3 | genus | bacteria | | 414371 |
| aureimarina | -3 | genus | bacteria | | 414367 |
| aulosira | 10 | genus | bacteria | | 212347 |
| atriotaenia procyonis | 2 | species | | helminths | |
| atopostipes | 2 | genus | bacteria | | 292480 |
| atopococcus | 2 | genus | bacteria | | 269773 |
| atopobacter | 2 | genus | bacteria | | 136491 |
| astrosporangium | 1 | genus | bacteria | | 404932 |
| asticcacaulis | 12 | genus | bacteria | | 76890 |
| asteroleplasma | 1 | genus | bacteria | | 2152 |
| aspromonas | 1 | genus | bacteria | | 518685 |
| aspiculuris tetraptera | 17 | species | invertebrates | helminths | 451377 |
| aspergillus westerdijkiae | 5 | species | plants | fungi | 357447 |
| aspergillus viridinutans | 4 | species | plants | fungi | 75553 |
| aspergillus ustus | 23 | species | plants | fungi | 40382 |
| aspergillus unguis | 4 | species | plants | fungi | 40381 |
| aspergillus tubingensis | 22 | species | plants | fungi | 5068 |
| aspergillus tritici | 1 | species | plants | fungi | 478866 |
| aspergillus terreus | 55 | species | plants | fungi | 33178 |
| aspergillus sydowii | 16 | species | plants | fungi | 75750 |
| aspergillus rugulosus | 2 | species | plants | fungi | 41736 |
| aspergillus persii | 1 | species | plants | fungi | 306094 |
| aspergillus penicillioides | 9 | species | plants | fungi | 41959 |
| aspergillus ochraceus | 42 | species | plants | fungi | 40380 |
| aspergillus novofumigatus | 2 | species | plants | fungi | 340412 |
| aspergillus nidulans | 151 | species | plants | fungi | 162425 |
| aspergillus lentulus | 6 | species | plants | fungi | 293939 |
| aspergillus kanagawaensis | 3 | species | plants | fungi | 41751 |
| aspergillus insulicola | 3 | species | plants | fungi | 138276 |
| aspergillus insuetus | 2 | species | plants | fungi | 469274 |
| aspergillus fumigatus | 109 | species | plants | fungi | 746128 |
| aspergillus flavus | 81 | species | plants | fungi | 5059 |
| aspergillus carbonarius | 26 | species | plants | fungi | 40993 |
| aspergillus calidoustus | 3 | species | plants | fungi | 454130 |
| aspergillus amstelodami | 23 | species | plants | fungi | 5054 |
| ascidianibacter | -3 | genus | bacteria | | 499061 |
| ascarops dentata | 1 | species | | helminths | |
| ascarops | 9 | genus | | | |
| ascaridia razia | -3 | species | | helminths | |
| ascaridia numidae | 2 | species | | helminths | 1004783 |
| ascaridia dissimilis | 6 | species | | helminths | |
| ascaridia columbae | 6 | species | invertebrates | helminths | 65462 |
| asanoa | 1 | genus | bacteria | | 195964 |
| asaia lannensis | 2 | species | bacteria | bacteria | 415421 |
| asaccharobacter | 2 | genus | bacteria | | 553372 |
| arthrospira | 25 | genus | bacteria | | 35823 |
| arthronema | 3 | genus | bacteria | | 241432 |
| arsukibacterium | 1 | genus | bacteria | | 336830 |
| arsenicicoccus | 2 | genus | bacteria | | 267408 |
| aromatoleum | 8 | genus | bacteria | | 551759 |
| arhodomonas | 2 | genus | bacteria | | 2368 |
| arenimonas | 2 | genus | bacteria | | 490567 |
| arenibacter | 7 | genus | bacteria | | 178469 |
| arcicella | 4 | genus | bacteria | | 217140 |
| archangium | 16 | genus | bacteria | | 47 |
| archaeoglobus | 59 | genus | bacteria | | 2233 |
| aquitalea | 3 | genus | bacteria | | 407217 |
| aquisalimonas | 2 | genus | bacteria | | 406099 |
| aquisalibacillus | 1 | genus | bacteria | | 485576 |
| aquincola | 3 | genus | bacteria | | 391952 |