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Bacterial ACC Deaminase Activity in Promoting Plant Growth on Areas Contaminated with Heavy Metals

The objective of this study was to explore the 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 the 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. The 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. The 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 ACC deaminase activity in the environment contaminated with multiple heavy metals. The use of selected microorganisms and plants will provide results in an increasing efficiency of phytoremediation.