The effect of phenols on the parameters of chlorophyll fluorescence and reactions of P700 in green algae Scenedesmus quadricauda

The effect of phenolics, present in wastes of pulp and paper industry, on photosynthesis in microalgae Scenedesmus quadricauda has been studied, analyzing the induction curves of prompt and delayed chlorophyll fluorescence and light curves of nonphotochemical quenching of fluorescence. Energization of photosynthetic membranes was impaired at low concentrations (0.1 mM) of phenol and pyrocatechol. At higher concentrations, phenol and pyrocatechol inhibited electron transport in PS II and increased the share of Q_B-nonreducing centers. As a result, the rate of P₇₀₀ reduction declined. These results indicate that the parameters of fluorescence induction curves can be used for detecting phenol and pyrocatechol in the environment at early stages of toxic effects.