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Effects of microcystins on and toxin degradation by Poterioochromonas sp.
Author(s) -
Ou Danyun,
Song Lirong,
Gan Nanqin,
Chen Wei
Publication year - 2005
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/tox.20114
Subject(s) - microcystin , superoxide dismutase , toxin , microcystis , cyanobacteria , cyanotoxin , microcystin lr , malondialdehyde , biology , microcystis aeruginosa , food science , microbiology and biotechnology , oxidative stress , environmental chemistry , chemistry , biochemistry , bacteria , genetics
A Chrysophyceae species, Poterioochromonas sp., was isolated from Microcystis cultures. This species can efficiently prey on Microcystis and can grow faster phagotrophically than autotrophically. The growth of Poterioochromonas sp. was stimulated in the presence of microcystin‐LR and microcystin‐RR (in concentrations ranging from 0.1 to 4 mg/L). The growth rate of Poterioochromonas was 4–5 times higher than the control, indicating the toxins serve as growth stimuli for this organism. A subculture of toxin‐treated cells, however, showed low cellular viability, suggesting that growth enhancement by microcystins was not a normal process. The antioxidant enzymatic activity of Poterioochromonas sp. was screened for toxicology analysis. Glutathione, malondialdehyde, and superoxide dismutase (SOD) content was up‐regulated within 8 h of exposure to microcystin‐LR (500 μg/L). A high level of SOD activity during exposure to the toxin indicated that SOD was involved in decreasing oxidative stress caused by microcystin‐LR. Simultaneously with growth, Poterioochromonas was able to degrade microcystin‐LR even, at a toxin concentration of 4 mg/L. This putative degradation mechanism in Poterioochromonas is explored further and discussed in this article. Our findings may shed light on understanding the role of Poterioochromonas in the aquatic ecosystem, in particular, as a grazer of toxic cyanobacteria and a biodegrader for microcystins. © 2005 Wiley Periodicals, Inc. Environ Toxicol 20: 373–380, 2005.