Enhanced heavy metal tolerance in two strains of photosynthetic Euglena gracilis by preexposure to mercury or cadmium

• Published in: Archives of environmental contamination and toxicology 1998-02, Vol.34 (2), p.128-135
• Main Authors: Devars, S, Hernandez, R, Moreno-Sanchez, R
• Format: Article
• Language: English
• Subjects: Animal, plant and microbial ecology; Applied ecology; Biological and medical sciences; Bioremediation; Cadmium; Detoxification; Ecotoxicology, biological effects of pollution; Effects of pollution and side effects of pesticides on plants and fungi; Euglena gracilis; Fundamental and applied biological sciences. Psychology; Heavy metals; Lead; Mercury; Oxygen consumption; POLLUTION DE L'EAU; POLUCION DEL AGUA; PRETREATMENT; PROTOZOA; RESISTANCE AUX FACTEURS NUISIBLES; RESISTANCE TO INJURIOUS FACTORS; RESISTENCIA A AGENTES DANINOS; WATER POLLUTION
• ISSN: 0090-4341; 1432-0703
• DOI: 10.1007/s002449900296

The effects of different concentrations of Hg, Cd, and Pb on cell growth, oxygen consumption, and production and contents of chlorophyll a and b of Z and B strains of Euglena gracilis was studied. Cell uptake of Cd and Pb was also determined. A greater cell density reached in the presence of Cd2+ correlated with a lower metal uptake capacity in B-strain cells. Cells of Z strain, preexposed to low concentrations of either Hg2+ (1.5 μM) or Cd2+ (50 μM) for several generations showed improved heavy metal tolerance (greater cell density and viability) together with similar metal uptake capacity. Because Cd2+ preadaptation but not Hg2+ pretreatment induced a significant increase in the content of acid-soluble thiols, the data suggest the existence of different mechanisms of heavy metal detoxification in Euglena. The fact that Z-strain cells showed a greater Cd2+ uptake under all the conditions assayed suggests that Z strain would be more suitable for bioremediation of polluted waters.