Effects of daily exposure of Cyanobacterium and Chlorophyte to low-doses of Pyrogallol

The effects of daily exposures to low-doses of the allelochemical pyrogallol on structural characteristics and metabolic states of the cyanobacterium Microcystis aeruginosa and the chlorophyte Selenastrum capricornutum were examined. A dose-dependent relationship was seen between single daily dose and the growth rate in S. capricornutum. After continuous exposures for 6-days, cell size of M. aeruginosa decreased but it increased in S. capricornutum, whereas, the cell granularity increased in M. aeruginosa and decreased in S. capricornutum. In M. aeruginosa, the pattern of metabolism was consistent with the trend of growth rate and when pyrogallol exerted its inhibitory effect, the daily dose could not be lower than 0.5 mg L-1. These results suggested that daily low-dose exposures was an effective and promising mode of allelochemicals inhibition of algae and mimic of the natural allelochemical-releasing process in the aquatic systems.