Toxic Effects of Single-Walled Carbon Nanotubes in the Development of E. coli Biofilm

Abstract

The impact of single-walled carbon nanotubes (SWNTs) on the different developmental stages of biofilms has been investigated using E. coli K12 as a model organism. Specifically, we investigated (i) the impact of SWNT concentration on cell growth and biofilm formation, (ii) toxic effects of SWNTs on mature biofilms, and (iii) formation of biofilm on SWNT-coated surfaces. The results show that at the initial stage of biofilm formation, SWNTs come into contact with bacterial cells prior to biofilm maturation and inhibit their growth. Furthermore, the results suggest that bacteria in mature biofilms are less sensitive to the presence of SWNTs than cells in other biofilm stages, similar to previous observations of biofilm resistance to antimicrobials. In mature biofilms, the soluble exopolymeric substances (EPS) secreted by the biofilm play an important role in mitigating the toxic effects of SWNTs. Upon exposure to SWNTs, biofilms without soluble EPS in the supernatant had a much more significant loss of biomass because of cell detachment from the biofilm than biofilms containing soluble EPS. To observe similar cell loss, biofilms with soluble EPS needed SWNT concentrations that were 10 times higher compared to biofilms without soluble EPS. Finally, SWNTs deposited onto surfaces affected significantly the subsequent biofilm development. Analysis of the total biomass and the area occupied by cells indicates that a SWNT-coated substratum has 10 times less biofilm colonization and biomass production than a control substratum without SWNTs.

<i>β</i>-Galactosidase Leakage from <i>Escherichia coli</i> Points to Mechanical Damageas Likely Cause of Carbon Nanotube Toxicity

“…The results demonstrate a definite toxic effect of CNTs in all these studies [10][11][12]. It has been suggested that the cytotoxic effect of CNTs on bacterial cells could have medicinal value by virtue of being bactericidal [13][14][15][16].…”

Comparison of the cytotoxic effect of polystyrene latex nanoparticles on planktonic cells and bacterial biofilms

“…Therefore, data on NP toxicity using planktonic bacteria are inappropriate for predicting the toxic effects of NPs on biofilms (Costerton et al 1995). Thus, the potential adverse effects of NPs on biofilms must be addressed, and to date, few studies have investigated this problem (Costerton et al 1995;Fabrega et al 2009Fabrega et al , 2011Choi et al 2010;Dror-Ehre et al 2010;Rodrigues and Elimelech 2010).…”

One-Time Addition of Nano-TiO2 Triggers Short-Term Responses in Benthic Bacterial Communities in Artificial Streams

“…Furthermore, enhanced production of extracellular polymeric substances (EPS) by benthic bacteria in the artificial streams could have contributed to the decrease in toxicity of nano-TiO 2 via similar mechanisms to those suggested for DOM (e.g., reduced illumination and ROS scavenging). Previous studies have demonstrated that bacteria can increase EPS production in response to nanoparticle exposure [65] and that high EPS production can confer enhanced resistance to nanoparticles [66][67][68].…”