球等鞭金藻对氟苯尼考胁迫的响应研究

研究以球等鞭金藻(Isochrysis galbana)为研究对象, 分析在不同浓度氟苯尼考暴露下, 球等鞭金藻的生长、叶绿素、类胡萝卜素和脂肪酸含量的变化。结果表明, 氟苯尼考对球等鞭金藻的生长呈“低促高抑”作用, 其72h-EC₅₀为17.12 mg/L; 随着暴露浓度(≥1 mg/L)增加, 细胞内叶绿素含量显著下降, 光合作用受到抑制, 而类胡萝卜素含量显著上升。脂肪酸和类胡萝卜素共同参与藻细胞的防御机制, 氟苯尼考(< 1 mg/L)暴露引起细胞内总脂肪酸含量显著降低。研究探究了水产养殖环境中抗生素残留的生态风险, 为水产养殖过程中抗生素的科学合理使用提供了理论依据。

THE EFFECT OF FLORFENICOL ON THE GROWTH OF MICROALGAE ISOCHRYSIS GALBANA

The wide distribution of antibiotics in various environmental media may pose a threat to aquatic ecosystem and non-target organisms. Florfenicol (FFC) is one of the most common used antibiotics in aquaculture. Its sustained release and degradation-resistance lead to the phenomenon of “pseudo-persistent” in aquatic environment. Microalgae are the primary producer in aquatic ecosystems, rich in polysaccharides, polyunsaturated fatty acids and carotenoids, and are also an important bait for marine bivalve larva. To explore the effects of antibiotic residues in aquatic environment, FFC (0.001, 0.01, 0.1, 1.0, 10, 20 and 50 mg/L) were treated the marine microalgae Isochrysis galbana for 72h, and algal growth, photosynthetic pigments contents and fatty acids were determined. The results showed that FFC at low concentrations (<1 mg/L) promoted the algal growth, and it had opposite effect at 10—50 mg/L. The half maximal effective concentration (EC₅₀) of FFC on I. galbana at 72h was 17.12 mg/L and the toxicity of this EC₅₀ belonged to moderate. The intracellular FFC concentration was elevated with the increased dose, reaching a maximum of 122 μg/mL in 50 mg/L treatment group. FFC (>1 mg/L) significantly decreased the contents of fatty acids and chlorophyⅡ, while significantly increased the content of carotenoids. In summary, low concentrations of antibiotics in aquatic environment may incur phytoplankton and red tide outbreaks. Changes in chlorophyⅡ content indicated that FFC may interfere the normal photosynthetic process and chlorophyⅡ synthesis of I. galbana. Carotenoids are critical photoprotective pigments, which absorb extra energy in chloroplast and avoid the damage of cell membrane from reactive oxygen species. Under the stress of FFC exposure (>1 mg/L) the induced carotenoids content and reduced fatty acids of I. galbana had protective role. The present study highlighted the potential risk of antibiotic residues in aquatic environment on algae, which provided theoretical support for the rational use of antibiotics in aquaculture.