Carbon nanomaterials can potentially stimulate phytoremediation of heavy metal contaminated soil by promoting plant biomass and root growth. Yet, the regulating mechanism of carbon nanomaterials on rhizosphere microenvironment remains poorly characterized. This study aimed to systematically assess the effects of multi-walled carbon nanotubes (MCNT) on the diversity and structure of rhizosphere soil bacterial and fungal communities, as well as activity of the soil microbial community and soil nutrient, in Solanum nigrum L.(S. nigrum)-soil system. Cd hyperaccumulator S. nigrum were cultivated in Cadmium (Cd) and Arsenic (As) contaminated soils amended with WCNT at 100, 500, and 1000 mg kg-1 for 60 days, respectively. Our results demonstrated greater activities of urease, sucrase, and acid phosphatase, and lower activity of cellulose in MCNT than in control soils. The organic carbon and available phosphorus were not affected by MCNT application, while there were significant reductions in available nitrogen and available potassium contents with the treatment of MCNT. Notably, the alpha diversity and community structure of bacterial and fungal communities in the rhizosphere soil did not vary among MCNT treatments. However, the soil microbial taxonomic composition in the soil receiving the MCNT application were changed. Compared to the control, MCNT application increased the relative abundances of the Chloroflexi and Actinobacteria phyla and decreased the abundance of the Proteobacteria phylum. In addition, the NMDA analysis revealed that soil bacterial community structure was significantly correlated with soil organic carbon, while sucrase activity had the highest relation to fungal community structure. This study highlighted the positive/negative effects of MCNT on some microbial functions, which improved our understanding of carbon nanotubes in heavy metal phytoremediation.

When nanoparticle and microbes meet: The effect of multi-walled carbon nanotubes on microbial community and nutrient cycling in hyperaccumulator system

ACS Fall 2021

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