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

A strain of an acidophilic, thermophilic alga, Cyanidium caldarium, was cul tured in a medium containing various metal ions (Al, Cd, Cr, Cu, Mn, Ni, Zn ). Among these metals, the alga tolerates especially high levels of Al: it can grow in a medium containing 200 mid Al, although the growth rate was re duced to 58%. The cellular Al concentration was kept at a considerably lowe r level as compared to the medium Al concentration. This may account for th e Al tolerance of the alga. Treatment of the algal cells with carbonylcyani de 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.