Strategies of response to copper, cadmium, and lead by a blue-green and a green alga

Abstract

The toxic metal ions Cu2+, Cd2+, and Pb2+ inhibited growth of the green alga Ankistrodesmus braunii and the blue-green alga (Cyanobacterium) Anabaena, strain 7120. Some concentrations of Cu lysed Anabaena 7120 at early, but not late, stages of growth. The other metals inhibited growth without causing lysis. Adding the chelating agent nitrilotriacetic acid (NTA) did not reduce, and in some cases increased, metal toxicity to Anabaena 7120. This suggests that these metals do not act on this alga only in the ionic form. When Anabaena 7120 grew in a sublethal concentrations of Cu(NO3)2 (10(-5)M) most of the Cu was found outside the cell, in nonionic form. About half the Cd was found to be cell associated when these algae grew in the presence of 10(-5)M Cd(NO3)2. Ankistrodesmus braunii bound substantial amounts of both Cd and Cu when growing in their presence. At certain Cu levels, the amount bound per cell remained virtually constant during growth. In Cd, the amount bound per cell was highest at the beginning of growth and then fell. Cell-associated metals were found in both wall plus membrane and cytoplasmic fractions of A. braunii after mechanical lysis. When these algae grew over dialysis sacs containing sediment loaded with Cd or Cu, substantial amounts of these metals left the sediment and entered the algal cultures. They were found both cell associated and in the culture medium of A. braunii. In cultures of Anabaena 7120, Cd removed from the sediment was found in both cells and culture medium, but Cu was found almost entirely in the culture medium. The effects that bloom of such algae might have on the mobilization of these metals from sediments in natural waters are discussed.

Cell composition and metal tolerance in cyanobacteria

“…The ability of cyanobacteria to accumulate heavy metals and radionuclides from their external environment has been demonstrated in several studies (Horikoshi et al 1979, Stratton & Corke 1979a, b, c, Baxter & Jensen 1980, Laube et al 1980, Massalski et al 1981, Jensen et al 1982, Wang & Wood 1984, Pettersson et al 1985a, Fischer 1985, Verma & Singh 1990, Avery et al 1991.…”

Phenylthiourea enhances Cu cytotoxicity in cell cultures: Its mode of action.

“…The effects of Cu have been widely studied in red blood cells (1,20), rat hepatocytes (28), frog skin (10), and marine flagellates (15,25,26). In several of these studies Cu has been suggested to affect the cell membrane.…”

Effects of metal speciation on growth of phytoplankton with special reference to iron

“…Thus methylated mercury compounds are more toxic than the Hg2+ ion (NUZZI, 1972) and vitamin B12 is one of the most available forms of cobalt known, Furthermore there is evidence that ligands such as citrate and nitrillotriacetate increase the toxicity of copper to green and blue-green algae (cyanobacteria) (GUY and KEAN, 1980;LAUBE et al, 1980). LAEGREID et al (1983) found a higher cadmium toxicity to Selenastrum capricornutum Printz than expected from the Cd 2+ concentration.…”