Toxicity of phenol and three nitrophenols towards growth and metabolic activities ofNostoc linckia, isolated from soil

Abstract

The toxicity of phenol and its nitrosubstituentso-nitrophenol (ONP),m-nitrophenol (MNP), andp-nitrophenol (PNP) was determined towards growth and metabolic activities of a diazotrophic cyanobacterium,Nostoc linckia, isolated from soil. Nitrophenols, but not phenol significantly inhibited the production of cell constituents (chlorophylla, protein and carbohydrate),14CO2 uptake and activities of nitrate reductase, nitrogenase, and glutamine synthetase. Growth of the organism under photoheterotrophic conditions (0.1% acetate) did not reduce the toxicity of nitrophenols. However, the addition of 10 μM adenosine triphosphate (ATP) to MNP treatments reversed the toxicity. Transmission electron microscopy revealed the secretion of mucous around the filament and induction of spore formation in the cultures subjected to nitrophenol toxicity.