TOXICITY OF PHENOL AND 3 NITROPHENOLS TOWARDS GROWTH AND METABOLIC-ACTIVITIES OF NOSTOC-LINCKIA, ISOLATED FROM SOIL

The toxicity of phenol and its nitrosubstituents o-nitrophenol (ONP), m-nitrophenol (MNP), and p-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 (chlorophyll a, protein and carbohydrate), (CO2)-C-14 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-mu-M 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.