Fatty Acids, Antibiotic Resistance, and Deoxyribonucleic Acid Homology Groups of Bradyrhizobium japonicum

The fatty acid compositions and multiple antibiotic resistance patterns of 32 strains of Bradyrhizobium japonicum correlated with two major deoxyribonucleic acid homology groups. In group I, the fatty acid composition was 1.3% 16:1 cis9 acid, 3.6% 16:1C acid, 8.8% 16:0 acid, 1.2% 19:0 cyclopropane acid, and 81.2% 18:1 acid. Group II contained 0.5% 16:1C acid, 11.1% 16:0 acid, 0.8% 17:0 cyclopropane acid, 24.7% 19:0 cyclopropane acid, and 62.3% 18:1 acid. Group I strains were susceptible to rifampin (500 μg/ml), tetracycline (100 μg/ml), streptomycin (100 μ/ml), chloramphenicol (500 μg/ml), erythromycin (250 μg/ml), carbenicillin (500 μg/ml), and nalidixic acid (50 μg/ml), whereas group II strains were resistant to these antibiotics. Both groups were resistant to trimethoprim (50 μg/ml) and vancomycin (100 μg/ml).