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Toxicity and adaptation of Dictyosphaerium chlorelloides to extreme chromium contamination
Author(s) -
SánchezFortün Sebastián,
LópezRodas Victoria,
Navarro Macarena,
Marvá Fernando,
D'ors Ana,
Rouco Mónica,
HaighFlorez David,
Costas Eduardo
Publication year - 2009
Publication title -
environmental toxicology and chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.1
H-Index - 171
eISSN - 1552-8618
pISSN - 0730-7268
DOI - 10.1897/08-489.1
Subject(s) - contamination , chromium , environmental chemistry , adaptation (eye) , environmental science , toxicity , chemistry , biology , ecology , organic chemistry , neuroscience
Metals are often spilled by industries into inland water environments, with adverse consequences. Numerous papers have reported that heavy metals produce massive destruction of algae. Nevertheless, algal populations seem to become tolerant when they have had previous exposures to heavy metals. Because the mechanisms allowing heavy metal tolerance of algae are not yet known, the present study analyzed the effect of hexavalent chromium on growth and photosynthetic performance of Dictyosphaerium chlorelloides, stressing on the adaptation mechanisms to chromium contamination. Growth and photosynthetic performance of algal cells were inhibited by Cr(VI) at 10 mg/L, and the 72‐h median inhibition concentration was established as 1.64 and 1.54 mg/L, respectively. However, after further incubation for a three month period in an environment with 25 mg/L of chromium, some rare, chromium‐resistant cells occasionally were found. A Luria‐Delbrück fluctuation analysis was performed to distinguish between resistant algae arising from rare, spontaneous mutations and resistant algae arising from physiological adaptation and other adaptive mechanisms. Resistant cells arose only by spontaneous mutations before the addition of chromium, with a rate of 1.77 × 10 −6 mutants per cell division. From a practical point of view, the use of both chromium‐sensitive and chromium‐resistant genotypes could make possible a specific algal biosensor for chromium.