硼化合物对普通小球藻的急性毒性效应

以普通小球藻(Chlorella vulgaris)为受试生物,采用批量培养法考察了不同质量浓度的硼酸和四硼酸钠对藻细胞生物量、ρ(Chla)、ρ(蛋白质)以及MDA(丙二醛)含量的96 h急性毒性效应,初步探讨了硼化合物对普通小球藻的毒性作用. 结果表明:在2种硼化合物胁迫下藻细胞的生长受到抑制,尤其是当ρ(硼)≥40 mg/L时抑制作用极其显著(P<0.01)；ρ(硼)为0~80 mg/L时,硼酸和四硼酸钠对藻细胞生长的最大抑制率分别为89.42%和86.72%,硼的抑制作用呈明显的剂量-效应关系,并且随暴露时间延长而减弱,96 h时藻细胞恢复生长. 硼酸和四硼酸钠对藻细胞的96 h-EC₅₀(半数有效浓度)分别为82.03和71.19 mg/L(以硼计)；与对照组相比,二者对普通小球藻的毒性效应表现为,随着暴露时间的延长,ρ(Chla)降低、ρ(蛋白质)先减后增、MDA含量升高. 研究显示,硼化合物对普通小球藻的毒性作用,可能是由于短期内引发藻细胞产生活性氧自由基并造成膜脂质和其他生物大分子的氧化损伤所致. 

Acute Toxic Effects of Boron Compounds on Chlorella vulgaris

Batch culture experiments were conducted to investigate the 96 h acute toxicity of boric acid and sodium borate on Chlorella vulgaris, with initial boron concentrations from 0 to 80 mg/L. The toxic mechanisms of boron compounds on C. vulgaris were examined by determining the biomass as well as the contents of chlorophyll a, protein and malonyldialdehyde (MDA). The results indicated that the growth of C. vulgaris was inhibited under the stress of boron, particularly when ρ(B)≥40 mg/L (P<0.01). The maximum percentage inhibition of C. vulgaris by boric acid and sodium borate were 89.42% and 86.72%, respectively. While clear dose-effect relationships were observed in the tests, the inhibiting effects decreased with the extension of exposure time, and the growth of C. vulgaris recovered at the end of the tests. The 50% effective concentration (EC₅₀) values of boric acid and sodium borate were 82.03 and 71.19 mg/L respectively (calculated as boron). Compared with the control group, the toxic effects of boron on C. vulgaris were:chlorophyll a contents decreased, protein decreased at first and then increased, and MDA increased. The toxicity could be related to the generation of reactive oxygen species, which induced oxidation damage to membrane lipid and other biological molecules in the short term.