The Effect of Toxic Doses of Copper upon Respiration, Photosynthesis and Growth of <i>Chlorella vulgaris</i>

Abstract

Abstract When cells of Chlorella vulgaris absorb copper under anaerobic conditions, subsequent respiration, photosynthesis and growth of the cells are all severely inhibited. This does not occur when the metal is absorbed under aerobic conditions. When, after aerobic absorption of copper, the cells are exposed to a period of anaerobiosis, respiratory inhibition is as profound as when the uptake is anaerobic. In this case, however, respiration must eventually recover, for growth is not affected so severely as it is when copper is taken up under anaerobic conditions. It is concluded that the extra copper absorbed under anaerobic conditions is directly or indirectly responsible for the greatly increased toxicity to growth, and that this copper is bound to sites not normally available under aerobic conditions. Some aspects of the apparently unique toxic effect of copper suggest that these extra sites are sulphydryl groups.