| Genus | Species Num | Strain Num | SOURCE |
|---|---|---|---|
| Brevibacterium | 3 | 3 | HMP/MGYG |
| Brevundimonas | 2 | 2 | HMP |
| Brucella | 9 | 13 | HMP |
| Buchnera | 1 | 4 | HMP |
| Bulleidia | 1 | 1 | HMP |
| Burkholderia | 12 | 16 | HMP |
| Butyricicoccus | 1 | 1 | MGYG |
| Butyricimonas | 2 | 2 | MGYG |
| Butyrivibrio | 1 | 2 | HMP/MGYG |
| Caldanaerobacter | 1 | 2 | HMP |