Extraordinary high aluminium tolerance of the acidophilic thermophilic alga,Cyanidium caldarium

Abstract

A strain of an acidophilic, thermophilic alga, Cyanidium caldarium, was cultured in a medium containing various metal ions (A1, Cd, Cr, Cu, Mn, Ni, Zn). Among these metals, the alga tolerates especially high levels of AI: it can grow in a medium containing 200 mM AI, although the growth rate was reduced to 58%. The cellular Al concentration was kept at a considerably lower level as compared to the medium Al concentration. This may account for the Al tolerance of the alga. Treatment of the algal cells with carbonylcyanide m-chlorophenylhydrazone in the presence of Al increased the cellular Al concentration. It was suggested that energy-coupled Al exclusion mechanisms can operate in the alga.