Submitted to: Letters in Applied Microbiology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/12/2012
Publication Date: 8/12/2012
Citation: Kiefer, L., Shelton, D.R., Pachepsky, Y.A., Blaustein, R.A., Santin, M. 2012. Persistence of E. coli introduced into streambed sediments with goose, deer, and bovine animal waste. Letters in Applied Microbiology. 55(5):345-353. Interpretive Summary: Pathogen and indicator microorganism die-off is of the paramount importance for assessing the microbiological quality of surface waters. Wildlife is an important source of pathogens and indicators, and yet published data on die-off of microbes from wildlife animal waste are absent. We present the first data on the die-off of E. coli from wildlife in streambed sediments. E. coli from deer and goose waste were added to two different sediments and die-off rates determined over approximately one month. For comparison, die-off rates were also determined for added bovine waste and indigenous strains (no waste added). With one exception, E. coli concentrations in sediments with or without waste were not significantly different, regardless of the souce of animal waste or sediment. This indicates the preferential survival of indigenous E. coli strains. Results of this work are expected to be useful to the researchers and practitioners in environmental management and modeling in that they provide guidance for interpretation and application of experimental data on E. coli die-off in streambed sediments and other environmental media.
Technical Abstract: E. coli is commonly used as an indicator of fecal contamination, and hence public health risk, in surface waters. Freshwater bottom sediments have recently begun to receive attention as important sources of water-borne E. coli. Wildlife can be a substantial source of fecal microorganisms entering streams. However, little is known about the survival of E. coli from wildlife in surface waters and sediments. The objective of this work was to compare the survival of E. coli introduced into streambed sediments from goose, deer and bovine feces vs. indigenous E. coli. In addition, E. coli survival from the different fecal sources was determined in two streambed sediments differing in texture and organic matter content. The survival experiments were conducted in flow-through chambers for 32 days; the two sediments were obtained from a first order creek in Maryland. E. coli and total coliforms were enumerated using the Colilert-18 Quanti-Tray system. Patterns of E. coli survival and inactivation rates were virtually identical for indigenous strains in both mineral and organic sediments. The addition of E. coli strains from bovine, goose or deer feces had relatively little impact on final E. coli concentrations, with one exception. In the organic sediment, deer-borne E. coli populations appeared to stabilize or increase with time. These results are consistent with previous research suggesting that indigenous sediment-borne E. coli strains are more persistent than those added to sediments. Furthermore, these results imply that die-off rates obtained from inoculating sediments with high concentrations of E. coli strains may result in inaccurate estimates of E. coli persistence because it minimizes the importance of indigenous strains which have lower die-off rates.