IMPROVED ENUMERATION OF BRADYRHIZOBIUM-JAPONICUM IN COMMERCIAL SOYBEAN INOCULANTS USING SELECTIVE MEDIA

Two selective media proposed for the enumeration of Bradyrhizobium jap onicum were tested using six strains of different origin and eight dif ferent commercial soybean inoculants. These media contained tetracycli ne, rifampicin and chloramphenicol to control bacterial contaminants, and cycloheximide and pimafucin to control fungal contaminants. They w ere compared with previously described selective media and plant infec tion technique counts. The proposed media provided better control of c ontaminants than previously described media, gave counts of B. japonic um similar to those obtained by the plant infection technique, and so may be used for quality control of commercial inoculants.