Characterization of Bacterial Isolates from Tailings Pond and Their Resistance to Heavy Metals and Antibiotics

lWater samples were collected from a tailings pond wastewater site in the Rudnik mountain area, where polymetallic ore flotation processes generate high concentrations of Pb²⁺, Zn²⁺, and Cu²⁺. The study aimed to identify microorganisms resistant to heavy metals and assess their potential for bioremediation. Growth capabilities under varying conditions, including temperature, pH, and NaCl concentrations, were analyzed using a spectrophotometer. Minimal inhibitory and lethal concentrations of tested substances were determined for both planktonic cells and their biofilms. Key isolates, namely Bacillus altitudinis PMFKG-R3, B. pumilus PMFKG-R15, B. cereus PMFKG-R46, Pseudomonas veronii PMFKG-R30, and Pantoea agglomerans PMFKG-R20, demonstrated growth ability at both 22 and 37°C and exhibited halotolerance, albeit sensitivity to acidic pH. Most isolates in both planktonic and biofilm forms displayed notable resistance to heavy metals, particularly Pb²⁺ and Zn²⁺, in line with the sampling location. Notably, planktonic cells were sensitive to antibiotics, while biofilms exhibited slightly higher resistance. Promising candidates for bioremediation purposes were identified in P. veronii PMFKG-R30 and P. agglomerans PMFKG-R20, which displayed resistance to heavy metals and sensitivity to antibiotics.