Effect of Triclosan Concentration on Growth Rate of Lemna Minor

The effect of triclosan exposure on growth of Lemna minor (common duckweed) was investigated over a 14 day treatment period with percent population change as the measured result. Triclosan is a common antibacterial compound in personal care products that frequently becomes an aquatic pollutant. Triclosan disrupts the bacterial enyol-acyl carrier protein reductase enzyme (ENR), a critical enzyme in fatty acid synthesis. Survival of all organisms depends on fatty acids to form membranes. As bacteria, some protozoa and plants share the ENR enzyme, it was hypothesized that triclosan exposure would affect the growth rate of the native aquatic plant Lemna minor in a dose dependent manner. Lemna individuals were exposed to triclosan concentrations of 0 parts per billion (ppb ), 10 ppb, 50 ppb, 100 ppb, 500 ppb and 1000 ppb, with number of individuals counted each day. Triclosan significantly impacted the growth of Lemna minor as early as three days into the study. As the study progressed, triclosan negatively affected Lemna growth at concentrations of 500 ppb and above, supporting the hypothesis that Lemna would respond to triclosan exposure in a dose dependent manner. Ongoing research is investigating the mechanism of triclosan action by studying aspects of lipid synthesis and membrane integrity. These results illustrate the sensitivity of aquatic plant to triclosan and indicate Lemna minor could be used as a marker for triclosan concentration in aquatic ecosystems