Donor plants were collected in spring from the area contam-inated with heavy metals surrounding zinc smelter in the Silesiaregion in Poland. Soil was separated from roots by washing withsterile 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 werethen 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 wereincubated at 30◦C for 2 (RCA, NFb, and LA) or 7 days (YEMA) to iso-late bacteria. Evaluation morphology and mobility of each isolatedbacterial strain was examined by light microscopy. Isolated bacteriawere tested for Gram coloration with a kit (Britania Laboratories)and for oxidase activity with disks (Britania Laboratories).