The uptake kinetics and intracellular location of cobalt (60Co), manganese (54Mn) and zinc (65Zn) have been characterized in Chlorella salina. Uptake of all three metals was biphasic. The initial rapid phase was independent of light, temperature or the presence of metabolic inhibitors. This first phase of metabolism-independent biosorption was followed by a slower phase of uptake that was apparently dependent on metabolism and decreased by incubation in the dark, or in the light at low temperature or in the presence of metabolic inhibitors. This latter phase of metal accumulation followed Michaelis-Menten kinetics. However, when expressed in the form of a Lineweaver-Burk plot two distinct phases were apparent for each metal with the following Km values (μM); Co2+, 19 and 266; Mn2+, 2 and 760; Zn2+, 4 and 635. For all three metals cellular compartmentation analysis showed that large amounts of metal were bound to intracellular components and to the cell wall. There was also a higher concentration of each metal in the vacuole than in the cytosol, indicating transport of the metals across the tonoplast which may, in part, account for the multi-phasic uptake systems detected. The influence of competing divalent ions on the active uptake of Co2+ and Mn2+ was also studied. When the concentration of divalent ion was the same as that of Co2+ the uptake of the latter was not affected, indicating a specific system for the uptake of Co2+. However, Mn2+ uptake inhibited by Mg2+, Zn2+ and Cd2+, but not by Co2+, which indicated that Mn2+, Mg2+ and Cd2+ may enter the cells via a common system with different affinities for each metal.
|Number of pages||7|
|Journal||Applied Microbiology and Biotechnology|
|Publication status||Published - May 1992|
- Metal Accumulation
ASJC Scopus subject areas
- Applied Microbiology and Biotechnology