Fig. 6.

The stages of determining the content of copper ions in the studied samples. At Stage I, the number of copper ions in native cells D.v-Cu.S and D.v-Cu.R was determined (the number of cells of the two strains in the suspension was the same - 3.9 × 10⁹ and the volume of cell suspensions was equalized) and the number of copper ions that were present in their culture medium. At Stage II, the cells were destroyed, and 7 g/l of copper sulfate was added to the obtained biomass (its amount was the same for the two strains), followed by determination of the amount of copper bound to the D.v-Cu.S and D.v-Cu.R biomass and the amount of remaining – unbound copper in the medium. At Stage III, the amount of easily removed (“weakly bound”) copper with biomass D.v-Cu.S and D.v-Cu.R was determined by water extraction. The squares represent the average values of the amount of copper from three determinations, and the histograms represent the comparative differences in the amount of copper ions in the studied samples between D.v-Cu.S and D.v-Cu.R.