Analysis of bacterial cell properties and transport in porous media

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.