Analysis of bacterial cell properties and transport in porous media
ABSTRACT The cell properties of Escherichia coli ATCC 11105 (gram-negative rod and motile) and Staphylococcus aureus ATCC 10537 (gram-positive coccus and immotile) and their transport in porous media were investigated in this study. Bacterial cell properties such as cell geometry, zeta potential, and hydrophobicity were analyzed using surface measurement and bio-imaging techniques. Transport of both bacteria was examined using column experiments in quartz sand, iron-coated sand (ICS), iron-coated sand pretreated with humic acid (ICS-HA), glass bead, and field soil (sandy loam). Experimental results revealed that E. coli had a larger equivalent diameter and were more hydrophobic than S. aureus, while the difference in zeta potential was not statistically significant even though E. coli had a slightly more negative value than S. aureus. Column experimental results demonstrated that the mass recovery of S. aureus was higher than that of E. coli in all porous media used in this study. These results indicate that transport of S. aureus was greater than E. coli under the given experimental conditions. This study demonstrates that pathogenic bacteria with different characteristics from E. coli can have different transport in porous media.
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ABSTRACT: Bacterial cells that enter the groundwater system commonly experience desiccation stresses (i.e., bacterial cells are directly exposed to air) when traveling through the unsaturated layer of soil. Little is known about the effects of desiccation on the transport of bacterial cells in the groundwater system. In this research, we investigated the transport of desiccated and non-desiccated Escherichia coli K12 (ATCC 10798) cells through saturated sand packs using laboratory column transport experiments. Cell desiccation was performed at 25°C under relative humidity (RH) levels of 22%, 53%, 75%, and 97%, respectively, and the desiccation duration was 22 h. Our results showed that desiccation reduced the viability of E. coli cells under all RH levels and increased the transport of E. coli cells under ≥75% RH levels. The increase in the transport of the desiccated E. coli cells was not related to changes in cell size or cell zeta potential. Desiccation under high (i.e., ≥75%) RH levels, however, led to lower cell hydrophobicity, which was found to be positively correlated with cell transport.Water Air and Soil Pollution 03/2011; 223(3). DOI:10.1007/s11270-011-0950-2 · 1.69 Impact Factor
Conference Paper: On shared Medium Architecture with Output Buffer ConstraintsAdvanced Communications and Applications for High Speed Networks, 1992. Proceedings., International Workshop on; 04/1992
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ABSTRACT: We investigated occurrence of selected compounds (4-t-octylphenol: 4-t-OP; 4-nonylphenols: 4-NP; bisphenol-A: BPA; estrone: E1; 17β-estradiol: E2; triclosan: TCS) and estrogenicity in surface water and sediment of the Yellow River in China by using combined chemical analysis and in vitro yeast screen bioassay. Estrogenic compounds 4-t-OP, 4-NP, BPA, E1, E2 and TCS were measured in the water samples, with their average concentrations of 4.7, 577.9, 46.7, 1.3, ND and 6.8 ng/L, respectively. In sediment, the average concentrations of 4-t-OP, 4-NP, BPA and TCS were 35.7, 0.5, 1.7 and 0.7 ng/g while E1 and E2 were not detected in the sediments of all selected sites. In general, the estrogenic compounds in surface water and sediment of the Yellow River were at relatively low levels, thus having medium to minimal estrogenic risks in most sites except for the site of east Lanzhou with high estrogenic risks.Environmental Pollution 10/2011; 165:241-9. DOI:10.1016/j.envpol.2011.10.005 · 3.90 Impact Factor