Uptake of Copper Ion by Green Microalgae

Abstract

The uptake of copper ion by several green microalgae was investigated. The copper tolerance differed with different species of the green microalgae and Chlamydomonas angulosa was the most copper tolerant green microalga. The amounts of copper taken up by the green microalgae rapidly increased in the first 0.5~2hr and then gradually increased with the passage of time. The amount of copper taken up slightly differed with different species of green microalgae. The relationship between the copper tolerance of the green microalgae and their copper uptake could be classified into four groups: 1) copper tolerant algae which take up large amount of copper, 2) copper tolerant algae which take up small amount of copper, 3) copper sensitive algae which take up large amount of copper, and 4) copper tolerant algae which take up small amount of copper. The amount of potassium in the algal cells rapidly decreased in the first 1~2 hr after copper supplying and then gradually increased. The ratios of cupric ion obtained from ESR measurements to the copper amounts from the neutron activation analysis differed with different species of green microalgae. We assumed that some part of cupric ion taken up by green microalgae was reduced to cuprous ion mediated by a metabolic process. About 35~83% of copper taken up by green microalgae was released by EDTA washing. For the copper tolerant green microalgae the ratio of copper eluted by EDTA washing was larger than that for the copper sensitive green microalgae. For the green microalgae which took up a large amount of copper the amount of copper eluted by EDTA washing was also large. The distribution of copper differed with different species of green microalgae.