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United States Department of Agriculture

Agricultural Research Service

Title: Establishing the Influnence of Starvation Upon the Transport of Environmental Escherichia Coli Isolates

item Haznedaroglu, Berat
item Bolster, Carl
item Walker, Sharon

Submitted to: ASM Conference
Publication Type: Abstract Only
Publication Acceptance Date: 1/20/2007
Publication Date: 5/25/2007
Citation: Haznedaroglu, B.Z., Bolster, C.H., Walker, S.L. 2007. Establishing the Influnence of Starvation Upon the Transport of Environmental Escherichia Coli Isolates. ASM Conference.

Interpretive Summary:

Technical Abstract: This study focuses on the influence of bacterial starvation on the surface chemistry and transport of 12 different E. coli isolates from varying sources including human, poultry, cattle, horse, and wildlife in traditional packed bed columns. The intention was to determine to what extent starvation affects the transport trends of E. coli in subsurface environments. Extensive surface analysis was conducted on all of the isolates (size, hydrophobicity, zeta potential, extracellular polymeric substance content, acidity, and bacterial surface charge) under normal and starvation conditions. Transport experiments through packed quartz sand were also conducted with E. coli under these conditions. To achieve starvation conditions, bacterial isolates were suspended in 10 mM KCl solution for 6, 12, and 18 hours at room temperature following the harvesting step and prior to experimentation. Cells exposed to starvation conditions revealed an interesting lack of trends. Surface analysis showed no relationship between the relative hydrophobicity of the cells and the length of the starvation periods (0, 6, 12, and 18 hr). Zeta potential values did not differ significantly versus time. Similarly, there was no trend observed in terms of the isolates’ surface charge density, for cells titrated across the range of pH 4-10. Additionally, transport experiments have shown this same inconsistency. It was found that the source of the E. coli isolate also plays a substantial role in the surface characteristics and transport ability. For example, E.coli isolates obtained from wildlife had the most negative zeta potential value; whereas cattle isolates were less negative, suggesting they would be retained to a greater extent in the subsurface due to reduced electrostatic repulsion between the cells and negatively charged sand. Other such trends between isolates will be presented and the implications for predicting pathogen fate in subsurface environments will be discussed.

Last Modified: 10/17/2017
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