FIG. 2.
Growth and polyphosphate levels of A. ferrooxidans in the presence of copper ions. A. ferrooxidans cultures were inoculated in sulfur medium with 1.75 mM Pi in the presence of the indicated concentration of CuSO4, and cells were counted daily (A). To determine polyphosphate levels (B), the cells in A were harvested in the early stationary phase, and polyphosphate was extracted and quantified by the nonradioactive enzymatic method. Two independent determinations were performed. The error bars represent the standard deviations.