Investigation of heavy metal resistance in some bacterial strains isolated from industrial soils

Abstract

Soil samples were collected from an industrial area in Kazanli{dotless}, Mersin, Turkey. Six heavy metals, Cr, Cu, Ni, Co, Cd, and Zn, were tested. ICP-AES analyses were carried out to detect the heavy metal levels of the soil samples. The analysis of test samples revealed high levels of Ni and Cr. A total of 272 Pseudomonas spp. and 161 Bacillus spp. strains were isolated from soils from 4 different sampling locations. The maximum tolerable metal concentrations (MTCs) of Cr, Cu, Ni, Co, Cd, and Zn for each isolate were determined. Resistance to Cr was found in 73.9% of the bacterial strains isolated from soil samples, whereas 26% of the isolates exhibited resistance to Ni, 18.4% to Zn, 11.5% to Cd, 9.2% to Co, and 7.3% to Cu. Observed maximum MTCs were 5 mM for Zn and Cu, 3 mM for Ni, and 2 mM for Cr. Plasmids of sizes 1.8, 2.1, and 28 kb were detected in most Pseudomonas spp. strains with resistance to Cu, Cr, Zn, and Ni. © TÜBİTAK.