The objective of this study was to explore possible improvement of plant growth using the activity of the bacterial enzyme ACC (1-aminocyclopropane-1-carboxylate) deaminase (endophytes and rhizobacteria). The beneficial effect of ACC deaminase activity was tested on plants growing under stress conditions (high concentrations of heavy metals: cadmium, lead, zinc in the soil). The bacteria were isolated from three plants species: Festuca rubra L., Agrostis capillaris L., Arabidopsis thaliana L. Heynh, acquired from the area contaminated with heavy metals. Strains with the highest ACC deaminase activity were used to prepare a bacterial consortium and inoculate the plants. It has been shown that inoculation of plants with ACC producing bacteria has a positive effect on their growth under stress conditions. The bacterial entophytes strains showed a higher activity of ACC deaminase, which resulted in a higher biomass growth of inoculated plants. PGPB bacteria may limit the toxicity of harmful ions and thus the increase the adaptive properties of plants. Moreover, it was discovered that the bacteria mainly belonging to genus Bacillus and Pseudomonas had the highest AAC deaminase activity in multiple heavy metal contaminated environment. The use of selected microorganisms and plants will provide results in an increasing efficiency of phytoremediation.