RESUMEN
The majority of the 50Bradyrhizobium japonicum strains tested were resistant to ampicillin, kanamycin, streptomycin and tetracycline in concentrations below 100 µg/ml but resistant to chloramphenicol in concentrations equal to or above 100 µg/ml. Two strains had high levels of resistance to ampicillin and to streptomycin and six strains were very sensitive to several antibiotics.
RESUMEN
Of 50 strains ofB. japonicum, 64%, 44% and 54% were resistant to the fungicides captan, pentachloronitrobenzene and tetramethylthiuram disulphate, respectively, at concentrations above those recommended for treatment of soybeans. 100% and 84% of the strains were resistant to the herbicides trifluralin and metribuzin, respectively, also at concentrations above those recommended for soybeans. No strain was resistant to alachlor above 3.5 µg/ml but 40% were sensitive to 2.5 µg/ml, these being, respectively, the maximum and minimum concentrations recommended for soybeans.