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Impact of carbon nanotubes on the ingestion and digestion of bacteria by ciliated protozoa

Nature Nanotechnology volume 3, pages 347–351 (2008)Cite this article

Abstract

Research on the toxicity of carbon nanotubes has focused on human health risks1, and little is known about their impact on natural ecosystems2. The ciliated protozoan Tetrahymena thermophila has been widely studied3,4 by ecotoxicologists because of its role in the regulation of microbial populations through the ingestion and digestion of bacteria5,6,7, and because it is an important organism in wastewater treatment and an indicator of sewage effluent quality8. Here we show that single-walled carbon nanotubes are internalized by T. thermophila, possibly allowing the nanotubes to move up the food chain. The internalization also causes the protozoa to aggregate, which impedes their ability to ingest and digest their prey bacteria species, although it might also be possible to use nanotubes to improve the efficiency of wastewater treatment8,9,10,11,12,13,14,15,16.

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Figure 1: Characterization of SWNTs.
Figure 2: Phase contrast micrographs of T. thermophila after addition of SWNTs.
Figure 3: Confocal and white light images of T. thermophila.
Figure 4: Effect of SWNTs on bacterivory of T. thermophila.

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Acknowledgements

The authors would like to thank D. Weber for his assistance in confocal microscopy, V. Dayeh for helpful discussions, M. Palmer for use of the cell culture laboratory and M.D.O. Pinheiro for assistance in CB assay setup. This work was supported by the startup fund for S.T. from the University of Waterloo. The laboratory of N.C.B. was supported by grants from Earth and Environmental Technologies (ETech) of the Ontario Centres for Excellence (OCE) and the Canadian Water Network (CWN).

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Authors and Affiliations

  1. Department of Chemistry, University of Waterloo, Waterloo, N2L 3G1, Ontario, Canada

    Parnian Ghafari, Xu Jin, Veronica Tsou, Himadri S. Mandal & Xiaowu (Shirley) Tang

  2. Department of Biology, University of Waterloo, Waterloo, N2L 3G1, Ontario, Canada

    Christine H. St-Denis, Mary E. Power & Niels C. Bols

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  1. Parnian Ghafari
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  4. Xu Jin
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Contributions

P.G. and X.S.T. conceived and designed the experiments, carried out experiments and data analysis, and co-wrote the paper. C.H.St.D. carried out the colony forming assay, replicated the CB assay, and supplied E. coli-gfp and Tetrahymena stock. M.E.P. carried out initial data acquisition and provided bioassay and instrument training. X.J. carried out AFM characterization of the SWNTs. V.T. carried out the survey and video recording under the contrast phase optical microscope. H.S.M. did EDAX characterization of SWNTs. N.C.B. conceived and designed the experiments, provided material support, co-analysed data and co-wrote the paper. All authors discussed the results and commented on the manuscript.

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Ghafari, P., St-Denis, C., Power, M. et al. Impact of carbon nanotubes on the ingestion and digestion of bacteria by ciliated protozoa. Nature Nanotech 3, 347–351 (2008). https://doi.org/10.1038/nnano.2008.109

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