Inhibitory Effects of Bidens pilosa Plant Extracts on the Growth of the Bloom-Forming Alga Microcystis aeruginosa

Abstract

Algal blooms are one of the greatest aquatic environmental concerns, and the control of algal blooms has become a great challenge in recent years. In this study, we evaluated the effects of Bidens pilosa plant extracts in comparison to those of several widespread plants, including rice (Oryza sativa), Pistia stratiotes, Eichhornia crassipes, and Pteris vittata, on the growth of the bloom-forming blue-green alga Microcystis aeruginosa. Both ethanolic and methanolic extracts of B. pilosa, in contrast to the other plant extracts, exhibited high inhibitory effects on M. aeruginosa growth at a concentration of 500 mg/L (dry weight equivalent, DWE). The inhibition efficiency in terms of the cell density and chlorophyll a concentration significantly reached 84–88% (p < 0.05). In these treatments, a change in algal culture color (from green to brown) and cell death were obviously observed. When we determined the effective concentrations, the B. pilosa extract at concentrations of 250 and 500 mg/L DWE showed significant inhibitory effects on M. aeruginosa growth (p < 0.05), whereas lower concentrations (50–125 mg/L DWE) showed slight or no effects. These data indicate that B. pilosa plant extracts could be used to control M. aeruginosa algal blooms.

http://bit.ly/2FkM1Sn