Thesis
In situ effective diffusion coefficient profiles in biofilms using pulsed field gradient-nuclear magnetic resonance (PFG-NMR)
Washington State University
Master of Science (MS), Washington State University
2009
Handle:
https://hdl.handle.net/2376/103318
Abstract
Diffusive mass transfer in biofilms is characterized by an effective diffusion coefficient. It is well-documented that effective diffusion coefficients vary by location in the biofilms. The literature studies are currently dominated by effective diffusion coefficient measurements for distinct cell clusters or in stratified layers of the biofilms showing this variation. Regardless of whether distinct cell clusters or surface averaging methods are used, the position-dependent measurements of effective diffusion coefficients are 1) invasive to the biofilm, 2) performed under unnatural conditions, 3) at the expense of killing cells, and/or 4) spatially restricted to only certain regions of the biofilm. Invasive measurements can lead to inaccurate results and prohibit further (time-dependent) measurements of biofilms which are important for mathematical modeling of biofilms. In this study we measured in situ effective diffusion coefficients in biofilms. Our goals were 1) to measure effective diffusion coefficients of water in live biofilms, 2) to monitor how the effective diffusion coefficients change in biofilms over time, 3) to quantify how heterogeneity of biofilms varies by age and depth, and 4) to correlate biofilm structure with effective diffusion coefficients in biofilms. We measured 2-dimensional effective diffusion coefficient maps in Shewanella oneidensis biofilms and generated 1-dimensional surface averaged effective diffusion coefficient profiles using PFG-NMR methods. All the results are presented as relative surface-averaged effective diffusion coefficients (Drs). We found that 1) Drs profiles varied for biofilms of differing ages, 2) Drs profiles changed with time and generally decreased with time, 3) all the biofilms we have used showed very similar Drs profiles near the top of the biofilm, 4) Drs profiles near the bottom of the biofilm were different for each biofilm, 5) heterogeneity increased near the bottom of the biofilms, and 6) biofilm heterogeneity increased with age.
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Details
- Title
- In situ effective diffusion coefficient profiles in biofilms using pulsed field gradient-nuclear magnetic resonance (PFG-NMR)
- Creators
- Ryan Scott Renslow
- Contributors
- H. Beyenal (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Chemical Engineering and Bioengineering, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; Pullman, Wash. :
- Identifiers
- 99900525069101842
- Language
- English
- Resource Type
- Thesis