光照历史对小檗碱化感抑藻效应的影响

Effects of Light Acclimation on Allelopathic Inhibition of Microcystis aeruginosa by Berberine

蓝藻水华频发严重制约淡水养殖业的健康发展,铜绿微囊藻(Microcystic aeruginosa)为富营养化水体中的优势种;中草药黄连的主要化感物质小檗碱(C20H18NO4)能够有效抑制铜绿微囊藻的生长,并具有环境友好和毒副作用小的特点,光照强度会影响小檗碱对铜绿微囊藻的抑杀效果。将铜绿微囊藻在光照和黑暗条件下分别培养8 d后重新接种至相同的初始密度,添加不同浓度小檗碱(2 mg/L和4 mg/L)后置于光照条件下继续培养6 d,通过分析测定铜绿微囊藻细胞密度和叶绿素荧光参数,研究施药前光照历史对小檗碱化感抑藻效应的影响。结果表明,铜绿微囊藻在黑暗胁迫8 d后表现出超补偿生长效应;2 mg/L小檗碱不能有效抑杀铜绿微囊藻,藻细胞密度和叶绿素荧光参数(Fv/Fm、ΦPSⅡ、ETRmax、Yield')均随培养时间延长先下降后升高,6 d时施药前黑暗处理组的藻细胞密度显著高于施药前光照处理组(P<0.05);4 mg/L小檗碱能够有效抑藻,6 d时藻细胞全部死亡,且施药前黑暗处理组与施药前光照处理组藻细胞密度和叶绿素荧光参数下降趋势相同;黑暗胁迫诱导的超补偿生长效应不会影响高浓度(4 mg/L)小檗碱的化感抑藻效应,但会影响低浓度(2 mg/L)小檗碱的化感抑藻效应。

Frequent occurrence of cyanobacteria blooms restricts the healthy development of freshwater aquaculture, and Microcystic aeruginosa is the dominant species in eutrophic waters. Berberine （C20HlsNO4） , the primary allel- ochemical substance of the Chinese herbal medicine rhizoma coptidis, can effectively inhibit M. aeruginosa growth with environment- friendly characteristics and low side effects but light intensity influences the inhibitory effects. The aim of this study was to further investigate the effects of acclimation to light conditions on allelopathic inhibition of M. aeruginosa by berberine. Before exposure to berberine, two groups of M. aeruginosa （A, B ） in triplicate were cultured in a 3 000 mL conical flask for 8 d under the same condition except for light intensity. Group A was exposed to a light intensity of 40 p.mol/（ m2 · s） under a regime of alternating 12hr periods of light and dark, while Group B was always in the dark. After the acclimation period, M. aeruginosa in Groups A and B, with the same initial cell density, were exposed to different concentrations （2 mg/L and 4 rag/L） of berberine for 6 d under the same light conditions. This resulted in six groups, each in triplicate： No 1 ,B Control group; No 2,B 2 mg/L ber- berine group; No 3,B 4 mg/L berberine group ; No 4,A Control group ; No 5,A 2 mg/L berberine group; No 6, A 4 mg/L berberine group. The cell densities and chlorophyll fluorescence parameters （ Fv/Fm、ΦPSⅡ , ETR and Yield） of M. aeruginosa for each group were determined and used to evaluate effects of light acclimation conditions on allelopathic inhibition of M. aeruginosa by berberine. The results show that M. aeruginosa showed over - com- pensatory growth after culture in dark for 8 d ; 2 mg/L Berberine could not inhibit M. aeruginosa growth effectively, and cell densities and chlorophyll fluorescence parameters decreased first and then increased significantly. After ex- posure to berberine for 6 d, cell densities of algae in group No. 2 were significantly higher than those in group No 4 （P 〈 0.05 ） ; However, 4 mg/L Berberine inhibited M. aeruginosa growth effectively, with 100% death of algal cells in 6 d. No differences in cell densities and chlorophyll fluorescence parameters were observed between group No. 3 and group No. 6. Darkness-induced compensatory growth appears to affect the allelopathie inhibitory effect of 2 mg/L berberine but not of 4 mg/L berberine.