The ability to determine the source of pollution is a necessary first step to developing control plans.
Bacterial source tracking (BST) is an important tool in identifying biological loadings to water bodies,
and is thus critical in developing appropriate policies for source water protection. Bacterial BST is used
to identify sources of fecal contamination using methods such as rep-PCR DNA, ribotyping, antibiotic
resistance and carbon source utilization (Bryan et al., 2004; Carson et al, 2001; Guan et al, 2002;
Hagedorn et al., 2003). The correct classification of a fecal source by BST ranged from just about 30%
up to 100%. For BST to work most effectively, an extensive library of sample from the watershed must
be developed.
One of the drawbacks of BST is that discrepancies frequently occur between the species found in the
watershed and the species taken from the water column. Standard methods for water sampling are to
collect grab samples from the water column. No sampling of sediment is done. E. coli is capable of
adhering to particles and settling out of the water column, and if this sorptivity is strain specific, then
this could explain the discrepancies that occur when using BST. Very little research has been performed
on strain specific fate and transport of E. coli.
This research investigated strain dependent differences in the ability of E. coli to sorb to
particles. Standard conditions with 2 g kaolinite, 10 mL sterilized river water adjusted to pH of 6.5,
about 3 x 10<sup>6</sup> cfu/mL starting concentration, and incubation for 20 minutes were used to perform these
experiments. The data demonstrated drastic differences in the ability of E. coli strains to sorb to
kaolinite, a common clay in the environment. E. coli isolated from avian species
sorbed very well, while E. coli isolated from a beef cow sorbed poorly. There was a 50-fold difference
in the sorptivity between these strains. This could mean that the avian-based E. coli readily drop out of
the water column, and because E. coli from beef cows do not, beef cow are the source measured by BST
in the water column even though the composition of the original mixed sample was much different. Includes 7 references, figure.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 160 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 3 |
| Published : | 11/01/2005 |
