Nano shapes micro : Impacts of metallic nanoparticles on microbial communities

This thesis aimed to investigate the impact of exposure dynamics, relative contributions of ENPs(particle) and ENPs(ion), and dosing regimens on the toxicity of ENPs varying in different physico-chemical properties, on the composition and functioning of soil microbial communities. The physico-chemical properties of ENPs could change their fate, and the exposure dynamics thus need to be taken into consideration for realistically characterizing the time-variable exposure in assessing toxicity. The metabolic profile of microbial community could change according to ENPs shapes, with nanoplates being more toxic than nanospheres and polygons. Regarding the microbial community composition, the effect of ENPs depended on exposure time and concentration. However, the alterations in community composition were not expressed in terms of community functioning, which indicates that genus specific changes occurred but not yet necessarily reflected biological significance with regard to community functioning. Functional redundancy might contribute to community tolerance to ENPs exposure. When exposed to more realistic ENPs exposure scenarios with multiple dosing frequencies instead of one-time injection, the repetitive exposure with low-dosing could induce a tendency towards larger alteration of both community composition and functioning. Our study thus provided further insights in understanding the impact of NPs on soil microbial communities towards environmentally relevant assessment. Conservation Biolog