Effects of di‐n‐butyl phthalate on growth and photosynthesis in algae and on isolated organelles from higher plants

Abstract

Di‐n‐butyl phthalate (DBF) is widely used as a plasticizer and has been found in all types of ecosystems. It inhibits growth and photosynthesis of green algae (Chlorella emersonii CCAP strain 211/8 h and Selenastrum capricornutum CCAP strain 278/4) at concentrations higher than 10‐5M. The IC50 value for CO2‐dependent oxygen evolution in algae was 3 × 10‐4M. The CO2‐reduction in isolated protoplasts prepared from barley (Hordeum vulgare L. cv. Simba) was also inhibited by phthalate. The IC50 value was 2 × 10‐4M. The electron transport in isolated thylakoids prepared from spinach was inhibited with an IC50 value of 3 × 10‐4M. The IC50 value for uncoupled electron transport extrapolated to zero chlorophyll concentration was 2.5 × 10‐5M. The effect of di‐n‐butyl phthalate was localized to reactions in photosystem II. Di‐n‐butyl phthalate could thus be a pollutant which affects growth and photosynthesis of plants. The reported IC50 values may be underestimated since di‐n‐butyl phthalate can attach to surfaces. The results are discussed in relation to observed effects of di‐n‐butyl phthalate on other organisms.