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Toxicity of parathion‐methyl to cells, akinetes and heterocysts of the cyanobacterium Cylindrospermum , sp. and the probit analysis of toxicity
Author(s) -
PANIGRAHI SIBANANDA,
PADHY SACHIDANANDA,
PADHY RABINDRA N
Publication year - 2003
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.2003.tb00286.x
Subject(s) - parathion methyl , agar , biology , heterocyst , nitrate , agar plate , growth medium , toxicity , parathion , potassium nitrate , cyanobacteria , spore , botany , food science , pesticide , chemistry , bacteria , anabaena , agronomy , ecology , genetics , organic chemistry , potassium
Summary The toxicity of a commercial formulation of the insecticide parathion‐methyl to the N2‐fixing filamentous cyanobacterium (blue‐green alga) Cylindrospermum , sp. was studied. A concentration of parathion‐methyl of 0.5 ppm caused growth increase in liquid growth media. The minimum inhibitory concentration of parathion‐methyl for both types (N 2 , fixing and nitrate supplemented) of liquid and solid media was 1.0 ppm. LC 50 values were: 4.4 ppm (liquid, N 2 , fixing), 5.5 ppm (liquid, nitrate supplemented), 3.3 ppm (agar, N 2 ‐fixing) and 4.0 ppm (agar, nitrate supplemented). LC100 values for N 2 ‐fixing liquid and both types of agar media were 10.0 ppm, while for the liquid nitrate supplemented medium the LC 100 was 12.0 ppm. Both akinete (spore) formation and germination were inhibited below the highest permissive concentration of 8.0 ppm, with the insecticide incorporated in the agar media. In soil, the LC50 and LC100 values for parathion‐methyl were 13.6 and 30 ppm, respectively. Both the dehydrogenase activity of heterocysts (monitored by 2,3,5‐triphenyl tetrazolium chloride reduction) and the nitrogen concentration of cultures (estimated by the micro‐Kjeldahl method) were affected by the insecticide, but the latter (N 2 ‐fixation) was more sensitive. The Kruskal‐Wallis H test on the numbers of vegetative cells in the filaments revealed that the insecticide significantly affected the division of vegetative cells. The cyanobacterium could detoxify the growth medium containing high levels (30 and 40 ppm) of the insecticide in short‐term exposures at the expense of cell viability.