Comparative Inhibitory Effects Of Berberine On Microcystis Aeruginosa And Chlorella Pyrenoidesa And The Mechanisms Involved

To develop berberine as low price and environment-friendly algicide which selectively target cyanobacteria,comparative effects of berberine on Microcystis aeruginosa and Chlorella pyrenoidesa,as well as mechanisms involved,were investigated.The results were presented as follows:1.The effects of berberine on the growth and PS? phytosynthetic capacity of M.aeruginosa and C.pyrenoidesaUnder normal light conditions,4 mg/L berberine could kill M.aeruginosa effectively and the cell density reached to 0 at day 6.Berberine decreased Fv/Fm and ETR significantly in the first 10 hours under normal light conditions.Under constant darkness,berberine exhibited no algacidal effects without light exposure.There was no significant difference in the algal cell densities and chlorophyll fluorescence parameters between groups with or without 4 mg/L berberine addition(P > 0.05).When light re-exposure from 2-d darkness,4mg/L berberine could inhibit M.aeruginosa growth,but could not kill algae absolutely after light re-exposure from darkness.Cell densities of M.aeruginosa exposed to 4 mg/L berberine kept constant first and increased after 5-d light recovery from darkness.Fv/Fm and ETR decreased first and then increased.C.pyrenoidesa exposed to 0 mg/L and 4 mg/L of berberine exhibited no significant differences in the growth performance and chlorophyll fluorescence parameters under three different light conditions(P>0.05).2.The effects of berberine on the photosynthetic rate and electron transport activity of M.aeruginosa and C.pyrenoidesaAfter exposed to berberine for 12 h,photosynthetic oxygen evolution rate and dark respiration rate of M.aeruginosa decreased with the prolongation of culture time.Photosynthetic oxygen evolution rate and dark respiration rate of M.aeruginosa decreased with the increasing berberine concentrations.There was no significant difference in PS ?electron transport activity between the control and berberine-added group(P>0.05)when berberine decreased electron transport activity of total chain and PS? significantly(P<0.05).No significant differences in C.pyrenoidesa photosynthetic oxygen evolution rate,dark respiration rate,electron transport activity of total chain,PS? and PS?,were observed between the control and berberine-added group(P>0.05).3.The effects of berberine on H2O2 contents and producing sites of M.aeruginosa and C.pyrenoidesaWith the prolongation of berberine-treated time,H2O2 contents of M.aeruginosa increased first and then decreased,following by the increase.As compared to the control,H2O2 contents of M.aeruginosa exposed to 5mg/L berberine increased significantly except 36h(P<0.05).With the prolongation of berberine-treated time,H2O2 contents of C.pyrenoidesa increased first and then decreased,following by the stabilization.There was no significant difference in H2O2 contents of C.pyrenoidesa between the control and berberine-added group(P>0.05).With the increasing berberine-treated time,H2O2 was observed in the thylakoid,the central and cytomembrane of M.aeruginosa in sequence.The distribution range increased gradually.As a photosynthesis-inhibiting allelochemical,berberine could inhibit the growth of M.aeruginosa with selectivity.The target site of berberine was in the PS? electron transport chain.Berberine could disturb the PS? electron transport,leading to ROS production.Berberine couldn't pass through the chloroplast membrane of C.pyrenoidesa and disturb its electron transport,so berberine had no algicidal effects on C.pyrenoidesa.