HR: 0800h
AN: H21B-1005    [Abstracts]
TI: High Cell Density Production of Europium-Labeled {\it Escherichia coli} for Tracing of Bacteria in Mantled Karst of Northwest Arkansas
AU: * Ting, T
EM: tting@uark.edu
AF: Department of Chemical Engineering, 3202 Bell Engineering Center University of Arkansas, Fayetteville, AR 72701 United States
AU: Thoma, G J
EM: gthoma@uark.edu
AF: Department of Chemical Engineering, 3202 Bell Engineering Center University of Arkansas, Fayetteville, AR 72701 United States
AU: Beitle, R B
EM: rbeitle@uark.edu
AF: Department of Chemical Engineering, 3202 Bell Engineering Center University of Arkansas, Fayetteville, AR 72701 United States
AU: Davis, R K
EM: ralphd@uark.edu
AF: Department of Geosciences, 113 Ozark Hall University of Arkansas, Fayetteville, AR 72701 United States
AU: Brahana, J V
EM: brahana@uark.edu
AF: Department of Geosciences, 113 Ozark Hall University of Arkansas, Fayetteville, AR 72701 United States
AU: Liu, H
EM: hxl05@uark.edu
AF: Department of Chemical Engineering, 3202 Bell Engineering Center University of Arkansas, Fayetteville, AR 72701 United States
AB: The preparation of europium-labeled {\it E. coli} as a bacterial tracer in our study is separated into two major steps: the production of large quantities of cells, and the labeling of the cells at high density. Indigenous {\it E. coli} isolated from a natural spring at the University of Arkansas's Savoy Experimental Watershed (SEW), Savoy, Arkansas was fermented in BIOFLO II (New Brunswick Scientific, Edison, NJ) bioreactor using a fed-batch technique. Either a concentrated glucose solution or an ammonium hydroxide solution was pulsed into the reactor automatically using closed-loop pH control in a reactor feeding strategy designed to optimize cell growth. {\it E. coli} cells were harvested at the stationary phase of the bacterial growth profile, washed and centrifuged prior to the europium labeling step. A concentrated europium chloride solution was prepared by dissolving europium (III) chloride in 1-L of deionized water; the salt solution was chilled at 6$^{o}$C overnight. A batch of 100-g wet weight of the washed {\it E. coli} was suspended in the chilled europium salt solution, and the cells were incubated at 6$^{o}$C for 2 hours with stirring. After the cold incubation, the cells were washed with chilled deionized water and centrifuged repeatedly to remove excess europium. We have successfully prepared 760-g wet weight of labeled {\it E. coli} using the high cell density fermentation and europium labeling technique in a 9-day period. Preparation of large quantities of viable europium-tagged bacteria is critical for use as an environmental tracer. The europium uptake by the {\it E. coli} was found to be 15-mg europium per gram of labeled cell (wet weight). A field injection of multiple tracers along with the europium-tagged {\it E. coli} was successfully performed during the summer of 2004 at SEW to elucidate the transport, storage and viability of fecal contaminants in a karst basin. Prior investigations suggest that, unlike conservative tracers, {\it E. coli} become deposited along the flow path in the aquifer, and are resuspended with subsequent recharge events. Fluorescein and Rhodamine WT were injected along with the europium tagged {\it E. coli}. Both dyes were conservatively transported to the primary spring discharge points in about 10-days. Unlike the dyes, {\it E. coli} moved in distinct pulses associated with recharge events. These findings document that the fate and transport of {\it E. coli} is significantly different than conservative tracers.
DE: 1829 Groundwater hydrology
DE: 1831 Groundwater quality
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting