Reyes Vincent C, Merino Nancy, Gedalanga Phillip B, Van Nostrand Joy D, Keely Scott P, De Long Susan K, Zhou Jizhong, Mahendra Shaily
Department of Civil and Environmental Engineering, University of California, Los Angeles, CA 90095.
Institute for Environmental Genomics and Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73072.
ACS Sustain Chem Eng. 2018 Sep 4;6(9):11642-11652.
Metallic nanoparticles (NPs), the most abundant nanomaterials in consumer and industrial products, are the most probable class to enter the environment. In this study, wetland-derived microcosms were incubated with copper nanoparticles (Cu-NP) and ionic CuCl to investigate acute (10 days) and chronic (100 days) exposure towards nitrogen cycling microorganisms. The microbial ecology of wetlands play a crucial role in balancing nitrogen in pristine environments as well as in areas impacted by high nutrient loads (e.g., at wastewater effluent discharges). Gene abundance and expression changes were monitored using the GeoChip 5.0 high throughput functional gene microarray and metatranscriptomic shotgun sequencing (RNA-seq), respectively. After 10 days, the Cu-NP impacted microbial communities experienced structural shifts within microorganisms associated with dissimilatory nitrogen reduction accompanied by lower nitrate removal as compared to the unexposed controls. By day 100, these differences were largely resolved and nitrate removal was similar to the unexposed control. Furthermore, the Cu-NP exposed microcosms tolerated copper and were more resilient and adaptive than the unexposed controls based on the abundance and expression of other functions, including electron transfer, metal homeostasis, and stress response. These findings suggest sudden influxes of Cu-NPs into wetland systems may impair nitrogen removal initially, but long-term microbial shifts and functional redundancy would promote the net flux of total nitrogen out of the wetlands.
金属纳米颗粒（NPs）是消费品和工业产品中最常见的纳米材料，也是最有可能进入环境的一类物质。在本研究中，将湿地衍生的微观生态系统与铜纳米颗粒（Cu-NP）和离子态CuCl一起培养，以研究对氮循环微生物的急性（10天）和慢性（100天）暴露情况。湿地的微生物生态在原始环境以及受高营养负荷影响的区域（例如废水排放处）的氮平衡中起着至关重要的作用。分别使用GeoChip 5.0高通量功能基因微阵列和宏转录组鸟枪法测序（RNA-seq）监测基因丰度和表达变化。10天后，与未暴露的对照相比，受Cu-NP影响的微生物群落经历了与异化氮还原相关的微生物结构变化，同时硝酸盐去除率降低。到第100天，这些差异基本得到解决，硝酸盐去除率与未暴露的对照相似。此外，基于包括电子传递、金属稳态和应激反应在内的其他功能的丰度和表达，暴露于Cu-NP的微观生态系统对铜具有耐受性，并且比未暴露的对照更具恢复力和适应性。这些发现表明，Cu-NPs突然流入湿地系统可能最初会损害氮的去除，但长期的微生物变化和功能冗余将促进湿地中总氮的净流出。
