Key Laboratory of Aquatic Resources Conservation and Development Technology Research, College of Life Sciences, Huzhou University, Huzhou City, Zhejiang Province 313000, China.
Environmental Protection Monitoring Centre Station, Huzhou City, Zhejiang Province 313000, China.
Sci Total Environ. 2018 Jul 15;630:526-535. doi: 10.1016/j.scitotenv.2018.02.217. Epub 2018 Feb 24.
Reducing the formation and growth of Microcystis colonies is an important prerequisite for the effective prevention and treatment of cyanobacterial blooms. Microcystis flos-aquae colonies was selected to investigate the potential of propionamide for use in controlling cyanobacterial blooms. Propionamide, one of the major allelochemicals in the root exudates of E. crassipes, was tested using different concentrations (0, 0.2, 1, and 2mgL) and dosing methods (one-time addition, semi-continuous addition, and continuous addition) to assess its effect on the growth of M. flos-aquae colonies. The results showed that in the presence of different concentrations of propionamide, the growth of M. flos-aquae colonies followed a logistic growth model, with a higher degree of fit at lower propionamide concentrations. With the semi-continuous addition of 2mgL propionamide, the growth of M. flos-aquae colonies was markedly inhibited; the relative inhibition ratio of algal cells reached >90% at day 7 of co-culture, and the colonial form gradually disintegrated, transforming mainly into unicellular and bicellular forms and small colonies (average diameter<50μm). Following the semi-continuous addition of 2mgL propionamide, the exopolysaccharide content, the chlorophyll-a concentration, and the maximum photochemical efficiency of photosystem II (Fv/Fm) trended downward in M. flos-aquae colonies, whereas the relative expression of the microcystin (MC) biosynthetic genes, mcyA and mcyH, was upregulated overall. Importantly, the synthesis of intracellular microcystin-LR (MC-LR) was decreased after an initial increase, and the extracellular MC-LR concentration did not differ significantly from that in the control group (p>0.05). Moreover, an acute toxicity test showed that 2mgL propionamide was generally non-toxic to Daphnia magna. In conclusion, appropriate use of propionamide could effectively control the expansion of M. flos-aquae colonies without potential risks to the ecological safety of aquatic environments; therefore, propionamide can actually be used to regulate cyanobacterial blooms in natural waters.
减少微囊藻水华的形成和生长是有效防治蓝藻水华的重要前提。本研究选择满江红根泌物中的主要化感物质丙酰胺为研究对象，采用不同浓度（0、0.2、1、2mg/L）和投加方式（一次性投加、半连续投加、连续投加），探讨丙酰胺对微囊藻水华生长的控制效果。结果表明，在不同浓度丙酰胺存在的条件下，微囊藻水华的生长均符合 Logistic 生长模型，低浓度丙酰胺下拟合度更高。采用半连续投加 2mg/L 丙酰胺，可明显抑制微囊藻水华的生长，藻细胞的相对抑制率在共培养第 7 天达到>90%，藻华的群体形态逐渐解体，主要转化为单细胞和双细胞形态以及小群体（直径<50μm）。半连续投加 2mg/L 丙酰胺后，微囊藻水华群体的胞外多糖含量、叶绿素 a 浓度和最大光化学效率（Fv/Fm）均呈下降趋势，微囊藻毒素（MC）合成基因 mcyA 和 mcyH 的相对表达量总体上调。更重要的是，细胞内微囊藻毒素-LR（MC-LR）的合成先增加后降低，胞外 MC-LR 浓度与对照组相比差异不显著（p>0.05）。此外，急性毒性试验表明，2mg/L 丙酰胺对大型溞一般无毒性。综上所述，合理使用丙酰胺可以有效控制微囊藻水华的扩展，不会对水生态环境安全造成潜在风险；因此，丙酰胺可以实际用于调控自然水体中的蓝藻水华。
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