BIOREMEDIATION AND AGRICULTURAL CROP GROWTH PROMOTION BY PSEUDOMONAS STRAINS

Abstract

This study evaluated the bioremediation and phytostimulation effects of Pseudomonas spp. strains in soil contaminated with heavy metals (Zn, Cu, Cd). The study determined the growth parameters (temperature, pH, growth medium) of Pseudomonas spp. strains. The study focused on contaminated soil and the model plant Phaseolus vulgaris. The elemental composition was determined using ICP-MS.  The results showed that bacteria of the genus Pseudomonas selectively influence the migration and bioavailability of heavy metals in the soil-plant system. Zn concentrations in plant tissues ranged from 5 to 15 mg/ml without significant differences, demonstrating that Zn is a physiologically regulated element. The copper concentration remained low in all variants (approximately 2.20, 2.46, and 2.56 mg/mL), which is attributed to the immobilization of bacteria. Significant changes in cadmium concentration were observed. While it was 34.57 mg/mL in the control, it increased to 51.85 mg/mL in the 0.001 M concentration variant and to 78.5 mg/mL in the 0.01 M concentration variant, indicating an increase in its translocation into the plant. The results of the soil analysis also confirmed this pattern. The concentration of Zn decreased from 7.59 mg/ml to 1.77–3.62 mg/ml, copper changed from 1.68 mg/ml to 1.18–3.22 mg/ml, and cadmium rose sharply from 11.53 mg/ml to 45–95.5 mg/ml. This indicates an increase in the mobilization of soluble forms of Cd. Overall, Pseudomonas bacteria have a minor effect on Zn, immobilize Cu, and mobilize Cd. These results are important when selecting a bioremediation strategy. Stabilization is effective for Cu, and there is potential for using phytoextraction technologies for Cd.