Donor plants were collected in spring from the area contam-inated with heavy metals surrounding zinc smelter in the Silesia region in Poland. Soil was separated from roots by washing with sterile water (selection of rhizosphere bacteria). Roots were thendisinfected with a solution of 70% ethanol for 3 min and then thor-oughly washing them with sterile water. The root surfaces were then sterilized in 3% sodium hypochlorite for 0, 2.5, and 10 min andagain washed with sterile water (endophytic bacteria isolation).Finally, roots were added with 0.9% NaCl (1:10) and maceratedwith mortar and pestle under sterile conditions. For tests 1 g ofmacerated tissue was placed in a tube containing 9 ml sterile 0.9%NaCl. Appropriate dilutions of tissue were prepared and next eachdilution was then plated on 4 types of media: Congo Red agar(CRA, Sigma Aldrich, congo red acid morpholine propanesulfonicicacid pigmentation) or nitrogen-free base (NFb) solid media (man-nitol 5 g; K2HPO40.6 g; KH2PO41.8 g; MgSO4·4H2O 0.2 g; NaCl0.1 g; CaCl2·2H2O 0.2 g; bromothymol blue (BTB) 2 ml, vitamins0.5 ml; microelements 1 ml, to isolate a free-living diazotrophicbacteria, Luria agar (LA) (Sigma Aldrich, L3272) to isolate nutrition-ally demanding bacteria, and yeast extract mannitol agar (YEMA)(Sigma Aldrich, Y3252) to isolate Rhizobiaceae bacteria. Plates were incubated at 30◦C for 2 (RCA, NFb, and LA) or 7 days (YEMA) to iso-late bacteria. Evaluation morphology and mobility of each isolated bacterial strain was examined by light microscopy. Isolated bacteria were tested for Gram coloration with a kit (Britania Laboratories)and for oxidase activity with disks (Britania Laboratories).