Science News 04/07/2011

Escherichia coli can survive long time in sediments

E. coli strains don't cause illness, but they are indicator organisms used by water quality managers to estimate fecal contamination

Studies by U.S. Department of Agriculture (USDA) scientists have confirmed that the presence of Escherichia coli pathogens in surface waters could result from the pathogen's ability to survive for months in underwater sediments.

Soil scientist Yakov Pachepsky works at the Agricultural Research Service (ARS) Environmental Microbial and Food Safety Laboratory in Beltsville, Md. He is conducting studies to learn more about where the E. coli pathogens in streambeds come from, where they end up, and how long they can survive. ARS is USDA's chief intramural scientific research agency.

Lab studies conducted by Pachepsky and his colleagues suggested that non-pathogenic strains of E. coli can survive much longer in underwater sediments than in the water column itself, and provided the first published evidence that E. coli can overwinter in the sediment.

The results also indicated that the pathogens lived longer when levels of organic carbon and fine sediment particles in the sediment were higher. In addition, when organic carbon levels were higher, water temperatures were less likely to affect the pathogens' survival rates.

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