Evaluation of Enzyme‐linked Immunosorbent Assay (ELISA) for Serological Identification of Different <i>Rhizobium</i> Strains*

Abstract

A double‐antidody sandwich method of enzyme‐linked immunosorbent assay (ELISA) previously used for serotyping of peanut Rhizobium isolates was applied for serological identification of fast‐ and slow‐growing Rhizobium strains belonging to different species. This technique is highly sensitive for specific detection of culture and nodule antigens and enabled the rapid screening of large numbers of nodules. ELISA absorbance values of heat‐treated, ultrasonically and mechanically disintegrated cells of the tested strains were consistently higher than those of untreated cells. The antisera to strains R. leguminosarum 250V and R. meliloti 111 obtained from individual rabbits differed in their suitability for ELISA, although they were very efficient in homologous agglutination reactions. The ELISA reactions of culture and nodule antigens were identical for all strains investigated.