This paper studied the allelopathic effect of Cylindrotheca closterium on the growth of Prorocentrum donghaiense, the model of harmful algal blooms in aquatic environment, by the co-culture tests and bioassay-guided fraction methods. The growth of P. donghaiense in co-cultures was observably suppressed by C. closterium, and P. donghaiense biomass in C/P = 3: 1 group increased slowly with a low growth rate of 0.18 d-1 after 4 days. Petroleum ether (PE) extract derived from C. closterium filtrates was isolated by C18 column and the allelopathy of all isolated fractions for P. donghaiense was investigated. After 96 h cultivation, the inhibition ratio of PE-Ⅲ and PE-Ⅷ fractions on P. donghaiense could reach up to 70.2% and 64.3% at the concentration of 10-fold when compared to control, while the other fractions displayed relatively low inhibitory effects on P. donghaiense. PE-Ⅲ and PE-Ⅷ fractions also decreased the chlorophyll content and maximum quantum yield of photosystem II (Fv/Fm) of P. donghaiense cells. The activities of superoxide dismutase (SOD), one of antioxidant enzymes, reduced around 8.3% and 13.7% following exposure to 2-fold PE-Ⅲ and PE-Ⅷ, and was significantly decreased following higher exposure concentrations. After 96 h of 10-fold PE-Ⅲ and PE-Ⅷ treatments, Catalase (CAT) activity reduced to 44.86% and 46.42% of that observed in the control group. At the same time, a significant increase in malondialdehyde (MDA) contents was observed. These findings suggested that PE-Ⅲ and PE-Ⅷ fractions contained main allelochemicals and possibly acted as promising algistatic agents for emergency handling of P. donghaiense blooms.

中文翻译：

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从Cylindrotheca closterium中分离出抗藻类物质，并抑制其形成花粉的现象。

通过共培养试验和生物测定指导的分馏方法，研究了Cylindrotheca closterium对东海原原藻生长，水生环境中有害藻华的模型的化感作用。梭状芽胞杆菌可明显抑制共培养的东海假单胞菌的生长，C / P = 3：1组的东海假单胞菌生物量在4天后缓慢增长，生长速率仅为0.18 d-1。用C18柱分离出从梭状芽胞杆菌滤液中提取的石油醚（PE）提取物，并研究了所有分离的级分对东海假单胞菌的化感作用。培养96 h后，在10倍浓度下，PE-Ⅲ和PE-Ⅷ级分对东海假单胞菌的抑制率分别达到70.2％和64.3％。而其他组分对东海假单胞菌的抑制作用相对较低。PE-Ⅲ和PE-Ⅷ组分也降低了东海假单胞菌光系统Ⅱ的叶绿素含量和最大量子产率（Fv / Fm）。抗氧化酶之一的超氧化物歧化酶（SOD）的活性在暴露于2倍PE-Ⅲ和PE-Ⅷ后降低约8.3％和13.7％，而在更高暴露浓度下显着降低。经过10倍PE-Ⅲ和PE-Ⅷ处理96小时后，过氧化氢酶（CAT）活性降至对照组的44.86％和46.42％。同时，观察到丙二醛（MDA）含量显着增加。这些发现表明，PE-Ⅲ和PE-Ⅷ级分含有主要的化感物质，并可能作为有希望的P应急处理剂。