表面活性剂对地表水中微生物的毒性效应

研究了甜菜碱和石油磺酸盐表面活性剂对地表水中微生物的数量和代谢活性的影响，并基于菌群16S rRNA基因的高通量测序，比较分析了表面活性剂作用前后微生物群落结构的变化.结果表明，两种表面活性剂胁迫下微生物的生长活性均遵循低浓度促进、高浓度抑制的作用规律，表现出明显的浓度依赖性.与空白组相比，在1.5g/L的表面活性剂的作用下，微生物数量、蛋白质含量以及脱氢酶的活性均明显降低，且同浓度下的甜菜碱表现出更高的生物毒性；菌群多样性分析发现，肠杆菌属（Enterobacter）以高于75%的比例成为所有样本中的优势菌属，从各组来看石油磺酸盐可有效提高肠杆菌属（Enterobacter）的相对丰度，对假单胞菌属（Pseudomonas）和根瘤菌属（Rhizobium）抑制作用显著；而甜菜碱则可明显增加假单胞菌属（Pseudomonas）和寡养单胞菌属（Stenotrophomonas）的菌属比例，抑制肠杆菌属（Enterobacter）和根瘤菌属（Rhizobium）的繁殖；通过表面活性剂与纯种菌的作用发现，表面活性剂可通过扰乱细菌的生长周期、破坏细胞膜结构来干扰细胞的正常生理功能，从而使其活性降低甚至死亡.

Toxic effects of surfactants on microorganisms in surface water

The effects of betaine and petroleum sulfonate surfactants on the quantity and metabolic activity of microorganisms in surface water were investigated in this study. In addition, we also analyzed the changes of microbial community structure before and after treatment with surfactants based on the high-throughput sequencing of the 16S rRNA gene of the flora. The results showed that the growth activities of microorganisms under the stress of these two surfactants all present the phenomenon of promotion in low concentration and inhibition in high concentration, showing obvious concentration dependence. Compared with the control group, the microbial biomass, protein content and dehydrogenase activity were significantly decreased in the presence of 1.5g/L surfactants, and microbial community showed higher biological toxicity with betaine surfactant than petroleum sulfonate at the same concentration. The analysis of flora diversity indicated that Enterobacter (with a ratio of more than 75%) was the dominant genus in all samples. From each group, petroleum sulfonate can effectively improve the relative abundance of Enterobacter, and exert a significant inhibitory effect on Pseudomonas and Rhizobium. However, betaine can significantly increase the proportion of Pseudomonas and Stenotrophomonas, and inhibit the reproduction of Enterobacter and Rhizobium. Through the interaction between surfactant and pure bacteria, it was shown that surfactant could interfere with the normal physiological function of cells by disturbing the growth cycle of bacteria and destroying the structure of cell membrane, resulting in the reduction of its activity and even death.