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Ribotyping to Determine the Host Origin of Fecal Contamination in Georgia's Coastal Waters

PI: Peter G. Hartel and William I. Segars (Dept of Crop and Soil Sciences, Univ of Georgia, Athens, GA, USA)

Support: GA DNR Coastal Zone Management (through a Coastal Incentive Grant)

Timeframe: 10/01/2001 - 09/30/2002 (complete)

Project Overview:
Microbial source tracking was used to identify the source of fecal contamination in Georgia's coastal waters. Fecal bacteria was isolated from various animals, including humans, and used to establish a host origin library of DNA "fingerprints". Environmental fecal bacteria isolates can then be matched to this library to identify the host origin. Targeted sampling (with ribotypes matching those in the contaminated sample) provides an inexpensive means for identifying human fecal contamination by bypassing the permanent database.

Accomplishments and Findings:

  • A microbial library containing 2000 Escherichia coli ribotypes isolated from Clarke, Cobb, Forsyth, Fulton, Glynn, McIntosh, and Tift Counties was supplemented by 150 additional isolates (75 each from birds and humans). Four hundred Enterococcus faecalis ribotypes (200 each from birds and humans) were also added to this host origin database.
  • Ent. faecalis was routinely detected in chicken feces (522 of 1,009 enterococcal isolates; 52%) and human sewage (317 of 720 enterococcal isolates; 44%), but rarely in chicken litter (12 of 787 enterococcal isolates; <2%).  Therefore, unless large numbers of wild birds are concentrated in one area, water samples collected during baseflow conditions with both high enterococcal and Ent. faecalis counts may indicate human fecal contamination.

  • A general sampling of the Sapelo River showed fecal enterococcal numbers ranging from <10 (below the limit of detection) to 990 colony-forming units (CFU) per 100 mL.  Fecal enterococcal numbers around one site ranged from <10 to 24,000 CFU per 100 mL. Bacterial source tracking conducted with Ent. faecalis as an indicator suggested that the fecal contamination in the river came from a wastewater treatment facility.


See related project, Combining Targeted Sampling and Fluorometry to Identify Sources of Human Fecal Contamination in Georgia’s Coastal Waters

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This page was updated October 13, 2006