PolyP was visualized on the native 7.5% or 10% polyacrylamide Ready Gels from Bio-Rad (Helcules, CA, USA). Electrophoresis was performed at 100 V for 1–1.5 h. Gels were incubated for 1 h. in fixative solution consisting of 25% methanol/ 5% glycerol, stained for 30 min with 0.05% -o-toluidine blue and destained in a fixative for 2 hours. To eliminate polyP, the samples were treated with 2 μg/ml exopolyphosphatase of Saccharomyces cerevisiae scPPX1.