| dc.contributor.author | Krittanut, Chaithawiwat | |
| dc.description.abstract | The effect of nanoscale zero-valent iron (nZVI) particles on bacteria from different
growth phases was studied. Four bacterial strains including Escherichia coli strains JMI09
and BW25 l l 3, and Pseudomonas putida strains KT2440 and Fl were experimented. The
growth characteristics of these strains were detennined. Their cells were harvested based
on predetermined time points corresponding to different growth phases and exposed to
nZVL The cell viability was determined by a plate count method. The cells in lag and
stationary phases showed higher resistance to nZVI for all four bacterial strains, whereas
the cells in exponential and decline phases were less resistant and were rapidly inactivated
when exposed to nZVI. Bacterial inactivation increased with the concentration of nZVI.
Furthermore, less than 14% reduction in viability was observed when the cells were
exposed to the leachate of nZVI suspension suggesting that the physical interaction
between nZVI and the cells is critical for bacterial inactivation.
To understand the physiology that underlines these phenotypes, the responses from
various oxidative stress gene knockout strains of E. coli BW25 l l 3 to nZVI were examined.
For each of these mutant strains, cells from different growth phases were collected and
exposed to nZVI. The viability of the cells was determined by a plate count method. All of
the mutant strains exhibited higher susceptibility to nZVI when compared to the wild type
strain. The results also indicated that different knockout strains exhibited different levels of
susceptibility to nZVI. Strain lacking RpoS, a global stress regulator, showed the highest susceptibility. Among different defensive enzyme mutants, sodA and sodB mutants
exhibited the highest vulnerability whereas sodC mutant revealed much less susceptibility,
suggesting that nZVI may induce oxidative stress inside the cells via superoxide
generation. The inducibility of catalase (hydroperoxidase I) was also investigated by
exposing the cells to nZVI and measuring a related gene expression using quantitative
polymerase chain reaction. Results suggested that nZVI repressed the expression of this
enzyme. | en_US |
| dc.publisher | North Dakota State University | en_US |
| dc.rights | NDSU policy 190.6.2 | en_US |
| dc.title | Effects of Nanoscale Zero-valent iron (nZVI) on Bacterial Viability: Roles of Growth Phases and Oxidative Stress | en_US |
| dc.type | Thesis | en_US |
| dc.date.accessioned | 2023-12-26T19:10:33Z | |
| dc.date.available | 2023-12-26T19:10:33Z | |
| dc.date.issued | 2011 | |
| dc.identifier.uri | https://hdl.handle.net/10365/33457 | |
| dc.subject.lcsh | Nanoparticles -- Toxicology. | en_US |
| dc.subject.lcsh | Iron. | en_US |
| dc.subject.lcsh | Bacterial cell walls. | en_US |
| dc.rights.uri | https://www.ndsu.edu/fileadmin/policy/190.pdf | en_US |
| ndsu.degree | Master of Science (MS) | en_US |
| ndsu.college | Interdisciplinary Studies | en_US |
| ndsu.department | Environmental and Conservation Sciences | en_US |
| ndsu.program | Environmental and Conservation Science | en_US |
| ndsu.advisor | Khan, Eakalak | |
| ndsu.advisor | McEvoy, John | |
