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Enterohaemorrhagic Escherichia coli, such as serotype O157:H7, are a leading cause of food-associated outbreaks. While the primary reservoir is associated with cattle, plant foods have been associated as sources of human infection. E. coli is able to growin the tissue of food plants such as spinach. While fecal contamination is the primary suspect, soil has been underestimated as a potential reservoir. Persistence of bacterial populations in open systems is the product of growth, death, predation, and competition. Here we report that E. coli O157:H7 can grow using the soluble compounds in soil, and characterize the effect of soil growth in …

It is widely believed that Escherichia coli does not survive for extended periods outside the intestines of warm-blooded animals, but recent studies show that E. coli strains can maintain populations in soil and water without any known fecal contamination. The objective of this study was to determine whether niche partitioning of E. coli occurs between cattle and their pasture. We sought to determine whether E. coli from bovine feces differed phenotypically and genotypically from isolates maintaining a population in pasture soil over winter.  Soil, bovine feces, and run-off samples were collected before and after introduction of cattle to the pasture. …

Current limitations in culture-based methods have lead to a reliance on culture-independent approaches, based principally on the comparative analysis of primary semantides such as ribosomal gene sequences.  DNA is remarkably stable in some environments, so its presence does not indicate live bacteria, but extracted ribosomal RNA (rRNA) has been viewed as an indicator of active cells.  Stable isotope probing (SIP) involves the incorporation of heavy isotopes into newly synthesized nucleic acids, and can be used to separate newly synthesized from existing DNA or rRNA.  H218O is currently the only potential universal bacterial substrate suitable for SIP of entire bacterial communities.  …