水稻秸秆浸泡液对蓝藻和绿藻生长选择性抑制作用

Selective Inhibition of Rice Straw Extract on Growth of Cyanobacteria and Chlorophyta

运用流式细胞仪研究了水稻秸秆浸泡液(RSE)对藻类生长、形态学特征(细胞大小)和生理参数(叶绿素荧光强度)的影响.RSE对有毒、无毒铜绿微囊藻(Microcystis aeruginosa)、有毒水华鱼腥藻(Anabaena flos-aquae)、鱼害微囊藻(Microcystis ichthyoblabe)这4种蓝藻和羊角月牙藻(Selenastrum capricornutum)、蛋白核小球藻(Chlorella pyrenoidosa)、斜生栅藻(Scenedesmus obliqnus)这3种常见绿藻生长的抑制作用具有选择性.RSE浓度为2.0~10.0 g·L^(-1)时,可以显著抑制蓝藻的生长,同时强烈影响了藻细胞的叶绿素荧光强度和细胞大小.有毒水华鱼腥藻、鱼害微囊藻、有毒和无毒铜绿微囊藻的7d EC50分别为1.72、2.21、2.92和5.72 g·L^(-1).暴露于RSE的蛋白核小球藻和斜生栅藻,细胞生长被促进了并观测到有群体形成;而对羊角月牙藻来说,当RSE浓度为1.0~4.0 g·L^(-1)时月牙藻生长和叶绿素荧光强度被抑制,但是当RSE浓度为8.0~10.0g·L^(-1)时,月牙藻生长被显著促进.总之,RSE对蓝藻生长的抑制效果强于羊角月牙藻、蛋白核小球藻和斜生栅藻,蓝藻光合系统Ⅱ反应中心的敏感性和绿藻群体的形成可能是造成两者对水稻秸秆敏感性不同的重要原因.

Rice straw is supposed to be an environment-friendly biomaterial for inhibiting the growth of harmful blooms of the cyanobacterium Microcystis aeruginosa. The effects of rice straw extract（RSE） on algal growth, morphologic parameters（cell size）, and physiological parameters（in vivo Chl-a fluorescence） were investigated using flow cytometry. We examined the selective inhibitory potential of rice straw on four cyanobacterial strains（toxic and non-toxic Microcystis aeruginosa, toxic Anabaena flos-aquae, and Microcystis ichthyoblabe）, in comparison with inhibitory effects on three common freshwater green algae（Selenastrum capricornutum, Chlorella pyrenoidosa, and Scenedesmus obliqnus）. Concentrations from 2.0 to 10.0 g·L-1 of RSE were found to efficiently inhibit the growth of cyanobacteria in a dose-dependent manner, simultaneously modifying the in vivo Chl-a fluorescence and cell size. The 50% growth-inhibition concentration（7 d） of A. flos-aquae, M. ichthyoblabe, M. aeruginosa（toxic strain）, M. aeruginosa（non-toxic strain） was 1.72, 2.21, 2.92 and 5.72 g·L-1, respectively. Interestingly, the growth and cell size of C. pyrenoidosa and S. obliqnus increased with the addition of RSE and colony formation was observed. In the case of S. capricornutum, the inhibitory effect of RSE on growth and in vivo Chl-a fluorescence occurred at 1.0-4.0 g·L-1, while RSE induced a stimulatory effect on algal growth at 8.0-10.0 g·L-1. Taken together, the sensitivity of cyanobacteria to RSE was significantly higher than that of S. capricornutum, C. pyrenoidosa and S. obliqnus. The higher sensitivity of PSⅡ reaction center of cyanobacteria and the ability to form colonies of green algae may have important implications for the species-specific allelopathic antialgal activity of rice straw.