Citation:

Reyes, V., P. Gedalanga, N. Merino, J. Van Nostrand, S. Keely, S. De Long, J. Zhou, AND S. Mahendra. Differential Sensitivity of Wetland-Derived Nitrogen Cycling Microorganisms to Copper Nanoparticles. ACS Sustainable Chemistry & Engineering. American Chemical Society, Washington, DC, 6(9):11642–11652, (2018). https://doi.org/10.1021/acssuschemeng.8b01868

Impact/Purpose:

This study characterized changes to nitrogen speciation and nitrogen cycling microorganisms in wetland-derived microcosms following acute and chronic exposure to copper nanoparticles (Cu-NPs). These findings suggest sudden influxes of Cu-NPs into wetland systems might impair nitrogen removal initially, but resulting long-term microbial shifts would promote the net flux of total nitrogen out of the wetlands.

Description:

Metallic nanoparticles (NPs), the most abundant nanomaterials in consumer and industrial products, are the most probable class to enter and potentially affect the environment. In this study, wetland-derived microcosms were incubated with copper nanoparticles (Cu-NP) and ionic CuCl2 to investigate acute (10 days) and chronic (100 days) exposures to nitrogen cycling microorganisms. Gene abundance and expression changes were monitored using the GeoChip 5.0 high throughput functional gene microarray and metatranscriptomic 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 of copper oxidase (cueO), copper efflux (cusC), and bacterial adaptive response (opuE, soxS, desR, baeS) genes. These findings suggest that 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.

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