Serology is a traditional method used for phenotypic classification of bradyrhizobia which have now been replaced by advanced genotypic analyses including 16S, ITS, multilocus sequence analysis (MLSA) and whole genome analysis. Bradyrhizobium strains are tested for reaction against polyclonal rabbit anti-Bradyrhizobium antisera.
Serology of University of Delaware Bradyrhizobium Culture Collection (UDBCC)
Polyclonal rabbit anti-Bradyrhizobium antisera were produced against 12 USDA reference strains (USDA 6, USDA 31, USDA 38, USDA 46, USDA 62, USDA 76, USDA 94, USDA 110, USDA 122, USDA 123) to perform serological reactions. Antisera are labelled according to the USDA reference strains used except for USDA 138 which is identified as 6 (after USDA 6).
Each serogroup is labelled as name(s) of antisera against which each strain shows reactions, ordered by strengths of the reactions (strongest to weakest).
Table 1: Definition of serogroup terms
| Serogroup | Reactions |
|---|---|
| 110 | Single reaction: Against USDA 110 antiserum |
| 31-110 | Multiple reactions: Against USDA 31 and USDA 110 antisera. Stronger reaction against USDA 31 antiserum compared to USDA 110 |
| 31-110-122 | Multiple reactions: Against USDA 31, USDA 110 and USDA 122 antisera. Strength of reaction goes from strongest to weakest against USDA 31, USD 110, and USD 122 antisera. |
| 122w | Weak reaction against USDA 122 antiserum |
| NR | No reaction |