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Écologie des Escherichia coli producteurs de Shiga-toxines (STEC) dans les effluents d'élevages bovins et le sol

Abstract : Enterohemorragic Escherichia coli (EHEC) is one of the most important foodborne pathogens. During the last decade, cattle environment has frequently been implicated as the cause of EHEC outbreaks. This work aims to study the prevalence of Shiga toxin-producing E. coli (STEC) cells on dairy farms, and their survival in cattle effluents and soil.
In dairy farms, a wide diversity of STEC strains, which were able to persist on various materials (water troughs, pen walls, soil, etc) was observed. In cattle effluents (untreated cattle manure and slurry), non-O157 STEC strains could be detected during more than 90 days. In turned manure heaps, the STEC survival is of only 45 days, and the high temperature recovered in the main body of the manure heaps (≥ 65°C) is associated with the serious decrease of STEC cells number.
In vitro, STEC O26 strains were detected in various manure amended-soil types for at least 1 year, even in presence of low moisture levels (i.e. less than 0,08 g H2O g-1 dry soil). The ambient temperature (i.e. 20°C versus 4°C) is significantly associated (P<0,001) with the highest STEC count decline in all soils tested. In situ, the persistence of STEC and their transfer from naturally contaminated bovine feces to subsoil layers were determined in different pasture units of a high mountain watershed located in North Alps. STEC are able to persist in bovine feces, and to be transferred in subsoil layers at a depth up to 20 cm, over a period of approximately 2 months, until the fecal material had completely decayed.
In the rhizosphere, STEC survival may be affected by antibiotic-producing microbial populations. However, using a 2,4-diacetylphloroglucinol (Phl)-producing Pseudomonas strain as a model of biocontrol rhizobacteria, any negative effect of the Pseudomonas production of Phl on E. coli O157:H7 survival in wheat rhizosphere was observed.
According to these results, cattle environment constitutes a second significant reservoir of STEC cells, and effective measures to prevent STEC cells entry into environment should be adopted.
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https://tel.archives-ouvertes.fr/tel-00200118
Contributor : Bastien Fremaux <>
Submitted on : Thursday, December 20, 2007 - 12:58:53 PM
Last modification on : Tuesday, October 20, 2020 - 11:02:42 AM
Long-term archiving on: : Monday, April 12, 2010 - 8:39:13 AM

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  • HAL Id : tel-00200118, version 1

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Bastien Fremaux. Écologie des Escherichia coli producteurs de Shiga-toxines (STEC) dans les effluents d'élevages bovins et le sol. Ecologie, Environnement. Université Claude Bernard - Lyon I, 2007. Français. ⟨tel-00200118⟩

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