and for P. putida, Ap, Sill" Su, or Nal at 200 j.tg/ml, Cm at400 j.tg/ml, and Km or Tc at 25 j.tg/ml

Antibiotics, according to strain sensitivity, were used at the following concentrations: tetracycline 2 μg/ml for Rm1021, BM7, BM299 and BM300, 4 μg/ml for LMG18864, 10 μg/ml for other Sinorhizobium strains and for E. coli; streptomycin 600 μg/ml and kanamycin 200 μg/ml were used for Rm1021; kanamycin for E. coli S17.1 was used at 40 μg/ml; gentamicin was used at 20 μg/ml for all strains