Date of Award

8-2012

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Environmental Toxicology

Advisor

Dr. Tamara L. McNealy

Committee Member

Dr. Stephen J. Klaine

Committee Member

Dr. Christopher L. Kitchens

Committee Member

Dr. J. Michael Henson

Abstract

An increase in the amount of money spent on nanotechnology has led to an increase in funding to support nanoparticle (NP) research. Due to their stable, beneficial properties, NPs are found in daily consumer products such as bike frames, socks, cosmetics, and sunscreens. As a result of this, these NPs have the potential to enter the environment and interact with various organisms that play integral roles in the ecosystem as a whole. The effect that NPs have on aquatic systems is largely unknown and understudied. Biofilms are an important structural and functional part of aquatic ecosystems, and comprise various microorganisms from bacteria to protozoa. NP use will increase the concentration of NPs in the environment, making them more likely to interact with biofilms. NP contamination of aquatic environments may lead to adverse effects on environmental organisms. Legionella pneumophila is a biofilm forming bacterium that can survive in a wide range of temperatures and pH. First, NPs were characterized in their stock solutions and the exposure media, moderately hard water (MHW). Biofilms were exposed to NPs with various core compositions and surface chemistries, and at two different concentrations. Changes in biofilm morphology, bio-volume and roughness coefficient were observed after exposure to low concentrations of 4 and 18 nm AuNPs, 4 nm PtNPs, and low and high concentrations of 8 nm Fe3O4 NPs. Larger 50 nm AuNPs, 8 nm AgNPs, or PSBs did not result in changes to the biofilm morphology. In addition, the number of viable cells being released from the biofilm after NP exposure increased as NP size and concentration decreased, but treatments were not statistically different from controls.

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