All isolates and HD-1 were grown in Embrapa medium (8 g/l nutrient broth; 1 g/l yeast extract; 1 g/l KH2PO4; 1 mg/l CaCO3; 1 mg/lMgSO4Æ7H2O; 0.1 mg/l FeSO4Æ7H2O;
0.1 mg/lMnSO4Æ7H2O; 0.1 mg/l ZnSO4Æ7H2O; pH adjusted to 7.0 by addition of NaOH), for 72 h., 200 rpm, 30 C. Cultures (600 ml) were centrifuged at 12,800g for 30 min, at 4 C (BR4i centrifuge Jouan), the cell pellets were frozen for 16 h and lyophilized for 18 h in Labconco model Lyphlock 18 freeze-dryer. Dried powders were resuspended in water to 10% (w/v) for use in bioassays.