Indexed on: 01 Jul '93Published on: 01 Jul '93Published in: Applied Microbiology and Biotechnology
A microalga, Chlorella vulgaris, and two diazotrophic cyanobacteria, Nostoc linckia and N. muscorum, all isolated from a rice soil, were compared for their response in terms of growth and metabolic activities to the application of carbofuran. The toxicity criteria included cell constituents (chlorophyll a, total protein, carbohydrate), 14CO2 uptake and nitrate reductase, besides nitrogenase activity (acetylene reduction) in the cyanobacteria. C. vulgaris and N. muscorum were more sensitive to carbofuran than was N. linckia. The significant toxicity of the insecticide, observed with higher concentrations of 20 and 50 μg ml−1, to nitrogenase activity in N. linckia was reversed by the addition of ATP at 10 μM. Transmission electron microscopy of the cultures, exposed to 50 μg carbofuran ml−1 showed certain cellular abnormalities, indicating interference of the insecticide with membrane properties.