title: Biodegradation of specified risk material and fate of scrapie prions in compost.
abstract: Composting may be a viable alternative to rendering and land filling for the disposal of specified risk material (SRM) provided that infectious prion proteins (PrP(TSE)) are inactivated. This study investigated the degradation of SRM and the fate of scrapie prions (PrP(Sc)) over 28 days in laboratory-scale composters, with and without feathers in the compost matrices. Compost was mixed at day 14 to generate a second heating cycle, with temperatures exceeding 65°C in the first cycle and 50°C in the second cycle. Approximately 63% and 77% of SRM was degraded after the first and second cycles, respectively. Inclusion of feathers in the compost matrices did not alter compost properties during composting other than increasing (P < 0.05) total nitrogen and reducing (P < 0.05) the C/N ratio. However, addition of feathers enhanced (P < 0.05) SRM degradation by 10% upon completion of experiment. Scrapie brain homogenates were spiked into manure at the start of composting and extracted using sodium dodecyl sulphate followed by detection using Western blotting (WB). Prior to composting, PrP(Sc) was detectable in manure with 1-2 log(10) sensitivity, but was not observable after 14 or 28 days of composting. This may have been due to either biological degradation of PrP(Sc) or the formation of complexes with compost components that precluded its detection.
authors.affiliation: Department of Agricultural, Food and Nutritional Science, University of Alberta, Edmonton, Alberta, Canada.
authors.forename: Shanwei
authors.initials: S
authors.lastname: Xu
authors.forename: Tim
authors.initials: T
authors.lastname: Reuter
authors.forename: Brandon H
authors.initials: BH
authors.lastname: Gilroyed
authors.forename: Sandor
authors.initials: S
authors.lastname: Dudas
authors.forename: Catherine
authors.initials: C
authors.lastname: Graham
authors.forename: Norman F
authors.initials: NF
authors.lastname: Neumann
authors.forename: Aru
authors.initials: A
authors.lastname: Balachandran
authors.forename: Stefanie
authors.initials: S
authors.lastname: Czub
authors.forename: Miodrag
authors.initials: M
authors.lastname: Belosevic
authors.forename: Jerry J
authors.initials: JJ
authors.lastname: Leonard
authors.forename: Tim A
authors.initials: TA
authors.lastname: McAllister
mesh_terms: D000393:Air Pollutants / Q000032:analysis; D000397:Air Pollution / Q000032:analysis; D001673:Biodegradation, Environmental; D008962:Models, Theoretical; D011328:Prions / Q000378:metabolism*; D012608:Scrapie / Q000378:metabolism*; D012987:Soil / Q000032:analysis*
chemical_list: D000393:Air Pollutants; D011328:Prions; D012987:Soil