Effects of aluminium on ATP pools and utilization in the cyanobacterium Anabaena cylindrica: a model for the in vivo toxicity

Abstract

ATP pools extracted from the cyanobacterium Anabaena cylindrica, grown in the absence or presence of AlCl3, were measured using the luciferin‐luciferase assay. Addition of low concentrations of AlCl3 (3.6–36 μM) increased the ATP pool 20–40% within 24 h, the effect being more marked with time. When using the Tris‐EDTA boiling technique for extraction of cellular ATP, the ATP from aluminium‐exposed cells appeared more stable during the extraction than the ATP from untreated cells. The higher ATP pools in aluminium‐exposed cells were also evident after dark treatment and addition of the phosphorylating inhibitors carbonylcyanide m‐chloro‐phenylhydrazone (CCCP) and N,N‐dicyclohexylcarbodiimide (DCCD). The formation of elevated ATP pools in cells exposed to aluminium was curtailed by high concentrations of cellular phosphate and postincubation at high pH (>8). These results favour the hypothesis that intracellular aluminium binds to ATP by competing with Mg2+ and, as a consequence, the stable Al3+‐ATP complex formed is no longer available for cellular metabolism. The cyanobacterium is assumed to compensate by increasing the total pool of ATP. At high AlCl3‐concentrations, and in particular at low phosphate: aluminium molar ratios (<1), aluminium apparently also interferes with the membranes in A. cylindrica as indicated by inhibited O2 production, reduced ATP production and cell lysis.