Impact of TiO₂ Nanoparticles on Growth, Biofilm Formation, and Flavin Secretion in Shewanella oneidensis

Abstract

Understanding of nanoparticle impacts on critical bacteria functions allows us to gain a mechanistic understanding of toxicity and guides us towards design rules for creating safe nanomaterials. Herein and using analytical techniques, biofilm formation, a general bacteria function, and riboflavin secretion, a species-specific function, were monitored in Shewanella oneidensis, a metal reducing bacterium, following exposure to a variety of TiO2 nanoparticle types (synthesized, Aeroxide P25, and T-Eco). TEM images show that dosed nanoparticles are in close proximity to the bacteria but they are not internalized. Using quartz crystal microbalance (QCM), it was revealed that S. oneidensis biofilm formation is slowed in the presence of nanoparticles. Though S. oneidensis grows more slowly in the presence of TiO2 nanoparticles, riboflavin secretion, a function related to the S. oneidensis metal reducing capacity, was increased significantly in a nanoparticle dose-dependent manner. Both changes in biofilm formation and riboflavin secretion are supported by changes in gene expression in nanoparticle-exposed S. oneidensis. This broad study of bacterial nanotoxicity, including use of sensitive analytical tools for functional assessments of biofilm formation, riboflavin secretion, and gene expression has implications for total ecosystem health as the use of engineered nanoparticles grows.

Toxicity of ZnO and TiO2 to Escherichia coli cells

“…A number of nanomaterials is reported to exhibit significant toxicity and/or antibacterial activity123456789101112131415161718192021222324252627282930313233343536373839404142434445464748, including ZnO and TiO 2 1. However, there is no consensus on the proposed mechanism of toxicity of nanomaterials despite numerous literature reports.…”

Enhanced detection sensitivity of Escherichia coli O157:H7 using surface-modified gold nanorods

“…The comparative growth condition results between AuNRs-and Si-AuNRs-treated bacteria cells at different concentrations are shown in Figure 5. The growth rate of bacteria was calculated by using its exponential phase as described by Maurer-Jones et al 35 Obtained results ( Figure 5A) clearly indicate that the AuNRs exposed cells showed more toxicity with no further cell growth at all concentrations whereas, Si-AuNRs-treated bacteria showed enhanced growth rate compared to control experiment, which resembles the nontoxic nature of the nanoparticles (Si-AuNRs). In detail, even at higher concentrations, viability was not altered for Si-AuNR-treated bacteria, but bare AuNR caused a dose-dependent decrease in the growth of O157.…”

“…It was noted that initial high absorbance values occurred from the scattering of nanoparticles in the sample ( Figure 5A). Based on the followed calculations from Maurer-Jones et al 35 it was apparent that the rate of growth of Si-AuNRs exposed bacteria was higher for lower concentrations, than that of control ( Figure 5B). In contrast, significant decrease in growth rate was observed for all five concentrations of AuNRs-treated bacteria against control ( Figure 5C).…”

ZnO and TiO2 nanoparticles as novel antimicrobial agents for oral hygiene: a review

“…Comparative analysis of the inhibitory effect of Ni NPs (41 nm) and NiO NPs (35 nm) on biofilm formation activity of mixed oral bacteria revealed greater effect of Ni NPs compared to NiO NPs (Khan et al 2013b). Engineered TiO 2 NPs impede the biofilm formation by Shewanella oneidensis (Maurer-Jones et al 2013). However, another study shows that the coating of surface by TiO 2 does not affect the biofilm formation activity of two early colonizers of the oral cavity, namely S. sanguinis and A. naeslundii (Fröjd et al 2011).…”