Effects of Cellular Metabolism and Viability on Metal Ion Accumulation by Cultured Biomass from a Bloom of the Cyanobacterium Microcystis aeruginosa

Abstract

The sorption of nickel, cadmium, and copper by cultured biomass from a naturally occurring bloom of Microcystis aeruginosa was demonstrated in two systems: cells suspended in culture medium and cells immobilized in alginate. Incubation in the absence of light, in the presence of metabolic inhibitors, and at 4 degrees C did not substantially decrease the copper accumulation by cells in culture medium. Heat-killed, formaldehyde-treated, and air-dried biomass samples sorbed nearly as much (or in some cases slightly more) copper as did viable samples.

FIG. 1

Time course of metal sorption by cultured cells from an M. aeruginosa bloom. (A) ○, 31.5 μM CuCl₂ (2.0 μg of Cu²⁺/ml); ▵, 7.87 μM CuCl₂ (0.5 μg of Cu²⁺/ml); cells at a density of 1.5 mg of CHL per liter. (B) ◊, 4.45 μM CdCl₂ (0.5 μg of Cd²⁺/ml); □, 8.52 μM NiCl₂ (0.5 μg of Ni²⁺/ml); cells at a density of 1.8 mg of CHL per liter. Error bars indicate the ranges of duplicate measurements.

FIG. 2

Relationship between bound and free copper at various concentrations of added copper (7.87 to 31.5 μM) and various biomass concentrations (0.68 to 1.8 mg of CHL/liter), for the steady-state conditions observed after 2 h of incubation at 29°C in culture medium. The arrow indicates the conditions of bound and free copper in subsequent studies of metabolic inhibition.