Behavior of fluorescent Pseudomonas under different concentrations of heavy metals (Zn and Cu)

The use of chemical fertilizers has resulted in the depletion of soils in mineral elements and telluric microorganisms. Thus, for an improvement in crop growth, the exploitation of telluric microorganisms such as Pseudomonas can be an alternative. Laboratory work has made it possible to isolate strains of Pseudomonas from the rhizospheres of tomato, eggplant and onion. These strains were also tested in the presence of different concentrations of certain metals (CuSO4 and ZnSO4 (0, 1, 3, 4, 5 and 6 mmol/l). The tests carried out in the laboratory in the presence of Cu and Zn revealed a very significant reduction in the number of colonies of the strains of Pseudomonas for the concentrations of 5 and 6 mmol/l. The results showed better zinc tolerance for both tomato and onion rhizosphere strains. In the presence of Cu, the strain isolated from tomato rhizosphere shows more tolerance to heavy metals. These results made it possible to isolate different strains of Pseudomonas and to specify their tolerance thresholds for heavy metals