Effective concentrations of nitrophenolics toward growth yield of selected microalgae and cyanobacteria isolated from soil.

The effective concentrations (EC), which cause a certain percentage of inhibition in growth yield, of four nitrophenolics (o-nitrophenol, m-nitrophenol, p-nitrophenol (PNP), and 2,4-dinitrophenol) and the major metabolites of PNP reduction (p-nitrosophenol and p-aminophenol) toward growth of two microalgae (Chlorella vulgaris and Scenedesmus bijugatus) and two cyanobacteria (Nostoc muscorum and Nostoc linckia), all isolated from soil, were determined following linear regression analysis. The EC50 values of the selected toxicants toward the test organisms were in the range of 32 to 227 micrograms ml-1. Such a wide range in EC figures emphasizes the need for a prior determination of EC values of a toxicant before establishing its toxicity pattern toward a nontarget microorganism.