纳米银对聚磷菌吸磷和释磷的影响及毒性效应

利用硼氢化钠还原硝酸银，并使用聚乙烯醇（PVA）作为分散剂，制备出分散良好、粒径为（14±3）nm的纳米银颗粒，考察了其对聚磷菌（Microlunatus phosphovorus）好氧吸磷和厌氧释磷的影响，以及产生的毒性效应.结果表明，在好氧状态下，7mg/L的纳米银能够完全抑制聚磷菌的生长（P <0.01），达到10mg/L时才能完全抑制聚磷菌的吸磷能力（P=0.01）；在厌氧状态下，大于20mg/L的纳米银才使聚磷菌释磷能力受到部分抑制（P <0.05）.活性氧簇（ROS）和扫描电子显微镜（SEM）的检测结果表明，纳米银使细菌体内ROS水平降低，部分细菌菌体表面塌陷，这说明，纳米银不但可以毒害聚磷菌菌体表面，还可以降低菌内ROS水平.

Effect of silver nanoparticles on phosphorus uptake and release of polyphosphate-accumulating bacteria and toxic effect

Silver nanoparticles (AgNPs) were obtained from the reduction of silver nitrate by sodium borohydride in the stabilizing agent of polyvinyl alcohol (PVA). The as-prepared AgNPs demonstrated an excellent property of dispersibility, with the nanoparticle size of (14±3) nm. The AgNPs were used to investigate the effect of silver nanoparticles on phosphorus uptake and release of phosphorus-accumulating bacteria (PAB) and toxic effect. The results showed that 7mg/L of AgNPs totally inhibited the growth of PAB (P <0.01), and 10mg/L of AgNPs completely suppressed the phosphorus uptake ability of PAB under aerobic condition (P=0.01). Under the anaerobic condition, AgNPs with concentration higher than 20mg/L only partly inhibited the phosphorus release of PAB (P <0.05). The results indicated that AgNPs decreased the ROS level of PAB, and made the partial collapse of bacteria surface structure by the SEM. These revealed that AgNPs can decrease the ROS of bacteria besides the direct effect on the bacteria surface membrane structure, which both might be the important reasons for AgNPs toxicity on PAB.