title: p-Nitrophenol toxicity to and its removal by three select soil isolates of microalgae: the role of antioxidants.
abstract: The nontarget effects, in terms of biochemical changes induced by p-nitrophenol (PNP) in three soil microalgae, Chlorella sp., Chlorococcum sp., and Heterochlamydomonas sp., and the PNP removal efficiency of these isolates, were determined. On exposure to 20 mg L(-1) PNP, Chlorella sp. showed greater activity of peroxidase, superoxide dismutase, and glutathione reductase as well as high contents of proline and carotenoids. While Heterochlamydomonas sp. exhibited higher levels of catalase and protein, Chlorococcum sp. produced greater amounts of malondialdehyde, a measure of lipid peroxidation, in the presence of PNP. Chlorella sp. tolerated PNP by producing large quantities of antioxidants coupled with less lipid peroxidation, while Chlorococcum sp. was susceptible, as evidenced by low antioxidant production and high lipid peroxidation. During 7-d exposure, Chlorella sp., Heterochlamydomonas sp., and Chlorococcum sp. were able to remove 39, 18, and 4% of 20 mg L(-1) PNP, respectively. The present results indicate that proline, carotenoids and malondialdehyde are the potential biomarkers for assessing PNP toxicity toward microalgae, and their response could be considered for differentiating tolerant and susceptible strains. Moreover, there is a clear correlation between PNP removal and antioxidant synthesis in microalgae on exposure to the pollutant.
authors: Centre for Environmental Risk Assessment and Remediation, University of South Australia, Mawson Lakes, and Cooperative Research Centre for Contamination Assessment and Remediation of Environment, Salisbury South, Australia.
authors: Suresh R
authors: SR
authors: Subashchandrabose
authors: Mallavarapu
authors: M
authors: Megharaj
authors: Kadiyala
authors: K
authors: Venkateswarlu
authors: Ravi
authors: R
authors: Naidu
mesh_terms: D000975:Antioxidants / Q000378:metabolism*; D002374:Catalase / Q000378:metabolism; D002708:Chlorella / Q000302:isolation & purification / Q000378:metabolism; D000460:Chlorophyta / Q000378:metabolism*; D004785:Environmental Pollutants / Q000378:metabolism*; D005979:Glutathione Peroxidase / Q000378:metabolism; D005980:Glutathione Reductase / Q000378:metabolism; D015227:Lipid Peroxidation; D008315:Malondialdehyde / Q000378:metabolism / Q000633:toxicity; D058086:Microalgae / Q000302:isolation & purification / Q000378:metabolism*; D009596:Nitrophenols / Q000378:metabolism*; D009195:Peroxidase / Q000633:toxicity; D012987:Soil; D013482:Superoxide Dismutase / Q000378:metabolism
chemical_list: D000975:Antioxidants; D004785:Environmental Pollutants; D009596:Nitrophenols; D012987:Soil; D008315:Malondialdehyde; D002374:Catalase; D009195:Peroxidase; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D005980:Glutathione Reductase; C024836:4-nitrophenol