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An Investigation into Metal Oxide Nanoparticle Toxicity to Bacteria in Environmental Systems Using Fluorescence Based Assays

Mileyeva-Biebesheimer, Olga

Abstract Details

2011, Doctor of Philosophy in Engineering, University of Toledo, Civil Engineering.
While photocatalytic bactericidal effect of titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles (NPs) is routinely studied, there is very limited information regarding the toxic properties of these NPs in the absence of light. This research was focused on the evaluation of possible toxic effect of TiO2 and ZnO NPs on pure planktonic cultures (Gram-Negative bacteria Escherichia coli and Gram-Positive bacteria Enterococcus faecium), single culture biofilm (E. coli), and anaerobic digester microorganisms in the absence of light. Fluorescent cell membrane integrity stain propidium iodide and dsDNA specific counter stain PicoGreen® were applied to distinguish damaged and intact cells. The pure culture and diluted sludge samples were incubated for 1 h with 0 – 500 mg⁄L of TiO2 and ZnO NPs. Biofilm was exposed to 0 – 100 mg⁄L of TiO2 and ZnO NPs for 24 h. Undiluted sludge samples were incubated for 144 h with 0 – 500 mg⁄L of TiO2 and ZnO NPs (0.31 – 15.43 μg NP⁄mg total suspended solids) or as titanium (Ti) in TiO2 calculated by weight: 375, 750, and 3752 μg⁄L or 0.01, 0.023, and 0.12 μg⁄mg TS. A statistically significant increase in the percentage of damaged cells was detected for pure culture of E. coli and diluted sludge samples at concentration 100 mg⁄L of TiO2 NPs. A pure culture of E. faecium and diluted sludge samples incubated with ZnO NPs did not exhibit an increase of damaged cells. The toxic effect was not significant for biofilm or undiluted sludge samples incubated with TiO2 NPs for 24 and 144 h respectively. Biofilm samples incubated with 100 mg⁄L of ZnO NPs demonstrated a statistically significant increase in the percent of damaged cells. Undiluted sludge samples incubated with 500 mg⁄L of ZnO NPs significantly reduced biogas production. This study demonstrated that fluorescent microscopy and cell membrane integrity stain propidium iodide may be utilized for evaluation of the toxic impact of NPs on microorganisms. This method enables evaluation of NPs impact on fastidious microorganisms and eliminates conventional plating techniques that strongly depend on culturability of the microorganisms.
Cyndee Gruden, PhD (Committee Chair)
Ashok Kumar, PhD (Committee Member)
Isabel Escobar, PhD (Committee Member)
Defne Apul, PhD (Committee Member)
Youngwoo Seo, PhD (Committee Member)
129 p.

Recommended Citations

Citations

  • Mileyeva-Biebesheimer, O. (2011). An Investigation into Metal Oxide Nanoparticle Toxicity to Bacteria in Environmental Systems Using Fluorescence Based Assays [Doctoral dissertation, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1302125170

    APA Style (7th edition)

  • Mileyeva-Biebesheimer, Olga. An Investigation into Metal Oxide Nanoparticle Toxicity to Bacteria in Environmental Systems Using Fluorescence Based Assays. 2011. University of Toledo, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1302125170.

    MLA Style (8th edition)

  • Mileyeva-Biebesheimer, Olga. "An Investigation into Metal Oxide Nanoparticle Toxicity to Bacteria in Environmental Systems Using Fluorescence Based Assays." Doctoral dissertation, University of Toledo, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1302125170

    Chicago Manual of Style (17th edition)