Analysis of lectin binding by Bradyrhizobium japonicum strains grown on nitrocellulose filters using peroxidase-labeled lectin.

A procedure was developed to assess the ability of wild-type and mutant strains of Bradyrhizobium japonicum to bind soybean lectin. The lectin-binding ability of bacteria grown on nitrocellulose filters was determined using peroxidase-labeled soybean lectin. The assay produced clear differences between strains known to be unable to bind soybean lectin and those which can. The assay gave results identical to those of the fluorescein isothiocyanate-soybean lectin-binding assay of T. V. Bhuvaneswari, S. G. Pueppke, and W. D. Bauer (1977, Plant Physiol. 60, 486-491) with regard both to the ability of particular B. japonicum strains to bind lectin and to the inhibition caused by N-acetyl-D-galactosamine. The method was used to screen Tn5-induced mutants of B. japonicum 2143 for their inability to bind soybean lectin. The procedure provides a sensitive and convenient method to screen Bradyrhizobium strains for the ability to bind soybean lectin.