title: Prion degradation in soil: possible role of microbial enzymes stimulated by the decomposition of buried carcasses.
abstract: This study is part of a European project focused on understanding the biotic and abiotic mechanisms involved in the retention and dissemination of transmissible spongiform encephalopathies (TSE) infectivity in soil in order to propose practical recommendations to limit environmental contamination. A 1-year field experiment was conducted with lamb carcasses buried in a pasture soil at three depths (25, 45, and 105 cm). Microbial community response to carcasses was monitored through the potential proteolytic activity and substrate induced respiration (SIR). Soil above carcasses and control soil exhibited low proteolytic capacity, whatever the depth of burial. Contrastingly, in soil beneath the carcasses, proteolysis was stimulated. Decomposing carcasses also stimulated SIR, i.e., microbial biomass, suggesting that proteolytic populations specifically developed on lixiviates from animal tissues. Decomposition of soft tissues occurred within 2 months at subsurface while it lasted at least 1 year at deeper depth where proteolytic activities were season-dependent. The ability of soil proteases to degrade the beta form of prion protein was shown in vitro and conditions of burial relevant to minimize the risk of prion protein dissemination are discussed.
authors.affiliation: Ecologie Microbienne, Université Claude Bernard Lyon 1-UMR CNRS 5557 - USC INRA 1193, bat. G. Mendel, 43 Bd du 11 Novembre 1918, 69 622 Villeurbanne Cedex, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Rapp
authors.forename: Patrick
authors.initials: P
authors.lastname: Potier
authors.forename: Lucile
authors.initials: L
authors.lastname: Jocteur-Monrozier
authors.forename: Agnès
authors.initials: A
authors.lastname: Richaume
mesh_terms: D000818:Animals; D001673:Biodegradation, Environmental; D018533:Biomass; D010450:Endopeptidases / Q000378:metabolism; D011328:Prions / Q000378:metabolism*; D012621:Seasons; D012756:Sheep / Q000378:metabolism* / Q000382:microbiology; D012987:Soil / Q000032:analysis*; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000032:analysis
chemical_list: D011328:Prions; D012987:Soil; D012989:Soil Pollutants; D010450:Endopeptidases