MADISON, WI, MARCH 9, 2009 Escherichia coli is a commonly used indicator organism for detecting the presence of fecal contamination in drinking water supplies. The importance of E. coli as an indicator organism has led to several studies looking at the transport behavior of this important microorganism in groundwater environments. Commonly only a single strain of E. coli is used in these studies, yet research has shown that a significant amount of genetic variability exists among strains of E. coli isolated from different host species and even from the same host species. If these genetic differences result in differences in cell properties that affect transport, different strains of E. coli may exhibit different rates of transport in the environment.
A scientist at the USDA-ARS Animal Waste Management Research Unit in Bowling Green, Kentucky, in collaboration with researchers at the University of California at Riverside, compared cell properties and transport behavior of 12 different E. coli isolates obtained from six different fecal sources. Results from this study were published in the March-April issue of Journal of Environmental Quality.
For all 12 E. coli isolates, the following cell properties known to affect bacterial transport in the environment were measured: surface charge, hydrophobicity, cell size and shape, and the composition of the extracellular polymeric substance. Transport behavior of the E. coli isolates was assessed by measuring the amount of cells that were able to pass through columns packed with clean aquifer sands. The measured breakthrough concentrations of the bacteria were then modeled so that transport parameters for each E. coli isolate could be estimated. Correlations between measured cell properties and transport parameters were investigated.
Although each E. coli isolate was subjected to the exact same storage and growth con
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Crop Science Society of America