Studies On The Inhibitory Effects Of Berberine On Microcystis

The cyanobacterial bloom caused by eutrophication is overflowing all over the world, andmore and more attention was paid to it in recent years. Microcystis aeruginosa, the majorbloom-forming algae, can release microcystin. Harmful bloom can result in aquaticenvironment deterioration and the health of human beings was threatened. To providescientific foundation for the development of environmental friendly inhibitor for bloom, theinhibitory effects of berberine on M. aeruginosa FACHB-905with the capability to producemicrocystin were investigated, and berberine was also used to inhibit the Microcystisflos-aquae in outdoor. The main results were presented as follows:1Acute toxicity test:Berberine could inhibit the growth of M. aeruginosa FACHB-905significantly. Theeffective concentration of inhibition was0.0010%and96h inhibitory rate reached up to90%.2The effects of environmental factors on the inhibition of berberine on the growth andextracellular microcystin of M. aeruginosa FACHB-905:Under the same environmental factors and at the same exposure time of berberine,inhibitory effects of berberine on M. aeruginosa increased with the increasing berberineconcentrations. Under the same environmental factors and at the same berberine concentration,inhibitory effects increased with the prolongation of exposure time. Under the initial densitiesof0.5-4.0×106ind/mL,0.0005%-0.0030%berberine exhibited allelopathic inhibitory effectson M. aeruginosa. The inhibitory rates reached100%in treatments with densities of0.572×106ind/mL and1.052×106ind/mL. Under the same exposure concentration andexposure time of berberine, the effects of light intensity on inhibition of berberine on M.aeruginosa exhibited the trend as follows:5000lx>3000lx>1500lx>0lx; the effects ofaeration mode on inhibition of berberine on M. aeruginosa exhibited the trend as follows:continuous aeration, diurnal aeration> overnight aeration> no aeration; the effects oftemperature on inhibition of berberine on M. aeruginosa exhibited the trend as follows:35oC>30oC>25oC.Under the same environmental factors, extracellular microcystin content in the controlincreased with the increasing algal cell density. In the treatments exposed to berberine,extracellular microcystin content increased with the increasing dead algal cell densities, and itmaintained relatively stable after berberine killed all algal cells. 3Effects of berberine on the bloom in outdoorBerberine exhibited significantly inhibitory effects on the M. flos-aquae.72h inhibitory rateof0.0010%berberine reach78.25%, and96h inhibitory rate reached89.98%. Levels of DO,pH, NH4-N and NO2--N decreased and contents of PO43--P、NO3--N increased after berberineexposure.4FDA-PI double staining testInhibitory rate determined using dark-field counting with FDA-PI fluorescein staining wasmuch higher than that determined with the bright-field counting for the dead algal cells wasmiscounted as live cell in the bright field. FDA-PI fluorescein staining was a more reliablemethod to assess the alleopathic inhibitory effects of berberine on M. aeruginosa growth.