Accumulation of arsenic in a unicellular alga Chlamydomonas reinhardtii

Abstract

The unicellular alga Chlamydomonas reinhardtii accumulated and biomethylated arsenic efficiently. A wall-less cell strain (CW-15) of Chlamydomonas reinhardtii proliferated in a low level arsenic-containing medium (0.01–0.1 mmol dm−3) more than that in an arsenic-free medium. Although the growth of the algal cells was only slightly more inhibited in a growth medium containing arsenic at a concentration of 1.0 mmol dm−3 than that in an arsenic-free medium, it was completely inhibited at concentrations of 10 and 100 mmol dm−3. Furthermore, transformed strains were obtained by random introduction of plasmid pJD67, carrying an Arg+ gene, into a wall-less cell Arg− mutant CC425 strain. Finally we selected a strain, named AS1, among the transformed CC425 of the arsenic-sensitive group. The accumulation of arsenic by the AS1 strain was about three-fold higher than that by the CW-15 strain and 80–90% of the inorganic arsenic was transformed into a dimethylarsenic compound. It is suggested that the AS1 strain is a suitable model for investigation of the accumulation and biomethylation of arsenic by microalgae in freshwater environments. Copyright © 1999 John Wiley & Sons, Ltd.