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Lead toxicity in cyanobacterial porphyrin metabolism
Author(s) -
Zaccaro María Cristina,
Salazar Carmen,
Zulpa de Caire Gloria,
Storni de Cano Mónica,
Stella Ana María
Publication year - 2001
Publication title -
environmental toxicology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.813
H-Index - 77
eISSN - 1522-7278
pISSN - 1520-4081
DOI - 10.1002/1522-7278(2001)16:1<61::aid-tox70>3.0.co;2-l
Subject(s) - chemistry , phycobiliprotein , porphyrin , photosynthesis , food science , tenera , dehydratase , dry weight , photosynthetic pigment , toxicity , environmental chemistry , pigment , tetrapyrrole , zoology , chlorophyll , horticulture , nuclear chemistry , botany , biochemistry , cyanobacteria , enzyme , biology , genetics , organic chemistry , palm oil , bacteria
The effect of Pb 2+ on growth, tetrapyrrole photosynthetic pigment content, total free porphyrin, and 5‐aminolevulinate dehydratase (ALA‐D) activity of a cyanobacterium, Microchaete tenera , and its ability to sequester Pb 2+ from the culture medium were studied. Pb 2+ was assayed by graphite furnace atomic absorption spectrophotometry. M. tenera growth and chlorophyll a content were not affected by 0.5, 1.0, and 6.0 ppm of Pb 2+ . These treatments doubled the protein content and increased the phycobiliprotein content by four times after 7 days. The ALA‐D activity decreased in all concentrations by 63% at day 7 and by 34% at day 14. As a consequence of ALA‐D inhibition, total free porphyrin also decreased by 64% at day 7 and by 40% at day 14. The highest biomass lead uptake (7454±565 μg Pb 2+ /g dry weight) was observed at day 3 with 6.0 ppm of Pb 2+ in the culture medium. Uptake coefficient was highest (3723±279 μg Pb 2+ g −1 dry weight/ppm of applied Pb 2+ ) with 1.0 ppm after 3 days. The increase in protein and antenna pigments on day 7 was probably a response to stress conditions and could explain why the toxic metal did not affect growth. ALA‐D inhibition and high lead biomass content confirm the importance of this enzyme as a biological indicator for stress. © 2001 John Wiley & Sons, Inc. Environ Toxicol 16: 61–67, 2001