抄録
Cell surface hydrophobicity of Bradyrhizobium japonicum strains 123ET and 138NR was studied as a factor in competition for the attachment to root and the nodulation of soybean. Hydrophobicity of the strains, which was measured by a biphasic water-hydrocarbon system, significantly changed with culture age having a maximum value in mid-log phase. Three days-old soybean (Glycine max cv. Tamahomare) were inoculated with the mixture of two strains, and grown for 3 weeks in sterilized vermiculite tubes. Bradyrhizobia attached to the seedling roots were released at 90 min after the inoculation by sonication and enumerated by plate counting. Two strains were distinguished by the difference in antibiotic resistance. Nodule occupancies by the strains were determined by the ratio of the strains on the seedling root surface, not in the inocula. Logarithm of the ratio of the strains on the root was highly correlated with the difference in hydrophobicity of the strains.
